WO1990012518A1

WO1990012518A1 - Energy return systems for footwear

Info

Publication number: WO1990012518A1
Application number: PCT/GB1990/000599
Authority: WO
Inventors: David Roy Collins
Original assignee: Trisport Limited
Priority date: 1989-04-20
Filing date: 1990-04-19
Publication date: 1990-11-01
Also published as: AU5549190A; GB8909021D0

Abstract

An energy return formation for accommodation in a slot in the heel or sole of a sports shoe comprises a rigid upper plate (18) and a rigid lower plate (20) which are guided for relative vertical movements by depending locating pegs (22) spaced along opposite margins of the former sliding within upstanding tubular sockets (23) of the latter. A resilient energy-storing membrane (21) lies interposed between an array of downwardly-acting supports (17) of the upper plate (18) and a similar, but laterally offset, array of upwardly-acting supports (19) of the lower plate (20). The membrane (21) is so arranged to be stressed, and to yield resiliently, under forces transmitted to it by the upper and lower supports (17) and (19) when a downwards load is applied to the formation. The membrane is provided by a moulded rubber member which presents also upper and lower sockets (24) and (25) which accommodate the upper and lower supports (17) and (19), respectively. In alternative constructions, upper and lower supports are moulded integrally with a resilient membrane, or otherwise secured to the membrane.

Description

ENERGY RETURN SYSTEMS FOR FOOTWEAR

Some articles of footwear, principally certain kinds of articles of footwear intended for use in sporting activities, are provided with resilient formations that lessen the shocks experienced by the users' feet when they are lowered into weight-bearing positions and that assist the users by exerting upward forces on their feet as they are lifted again. Arrangements utilising formations of that kind are generally referred to as energy return systems, and the expression "energy return" will be used accordingly herein. Hitherto energy return systems have been employed almost exclusively in the heels of articles of footwear, but it is to be understood that the present invention is not so restricted and that an energy return system in accordance with the present invention can be employed in any desired location or in each of two or more desired locations in an article of footwear.

According to the present invention there is provided, in or for an article of footwear, an energy return formation presenting an array of downwardly-acting upper supports, an array of upwardly-acting lower supports which are offset from the upper supports, and resilient energy-storing means extending between adjacent upper and lower supports to yield resiliently upon a downwards load applied to the formation being transmitted thereto by the upper and lower supports.

In a preferred construction, the energy-storing means is provided by a resilient intervening membrane coming between the upper and lower supports. The membrane (which term, it is to be understood, is not used herein in any particularly narrow sense) may be formed by a single element or may comprise a plurality of plate-like elements or laminae stacked together. The membrane may be of uniform thickness, or may be of progressively increasing or decreasing thickness from one location to another; for example, those parts thereof that are likely to be subjected to the greatest loading in use may be thicker than those parts that are likely to be subjected to lesser loading. Alternatively, or in addition, a membrane may have local variations in thickness; for example, those parts thereof immediately adjacent to each support may be thicker than parts further from the supports. The membrane would normally be of a generally flat or gently curved configuration, but if desired may be of undulating (wavy) configuration.

When the membrane comprises two or more elements stacked together, the elements may be integrally interconnected at adjacent edges; for example the membrane may be formed by a single sheet of flexible and resilient material that is folded over on itself to form two or more layers. In particular, in one arrangement of that kind, an energy support system comprises a single sheet of flexible and resilient material, provided on only one face with integral supports, and -folded so that areas of the other face overlie one another whereby the sheet_, then constitutes two stacked elements the supports on one of those elements constituting upper supports and those on the other constituting lower supports.

It is to be understood that two or more energy return formations, each embodying the present invention, may be superimposed on one another, although it is envisaged that this would not normally be the case. Nevertheless, if such an arrangement were to be used, the upper supports of one formation could well constitute the lower supports of a system above it.

The supports may be of any of a variety of forms, and in any one system there may be supports of a single form or of two or more different forms.

One form of support does not extend far in any direction parallel with the plane of an adjacent part of the associated membrane; in that form each support may be of round, square or other compact cross-section. Each support may be solid or hollow, as desired, and in the latter case each may be of tubular form. The upper supports may be disposed in a regular array, and may occupy the intersections of a notional grid or network of lines extending over the membrane, while the lower supports may be disposed in a similar array which is offset relative to the upper array so that each support of one array is spaced away from supports of the other array, the spacing preferably being uniform so that in use adjacent parts of the membrane yield to a similar extent but in opposite directions.

Another possible form of support is an elongate rib. A plurality of ribs may be spaced apart, the ribs preferably being spaced apart at uniform or substantially uniform intervals. A rib may be of any suitable shape; it may, for example, extend in a straight line across a face of the associated membrane, or it may extend along an arcuate line or along a wavy line. In a further alternative each rib extends along a line of circular, oval or other endless shape, and adjacent ribs are concentric or approximately concentric with it. Each rib constituting an upper support in such an arrangement is preferably located half way between a pair of adjacent ribs constituting lower supports.

An energy return formation may be arranged to be accommodated between surfaces that are spaced uniformly apart; such surfaces may be planar and mutually parallel or they may be gently curved. Alternatively a formation may be accommodated between surfaces between which the spacing varies somewhat from one part to another. For example the surfaces may be planar but inclined to each other at a small angle, typically an angle of about 5° or even less, so that the formation occupies a wedge-shaped space between the surfaces. Alternatively at least one of the surfaces may be slightly or gently curved; for example the lower surface may be planar while the upper surface is slightly curved to conform at least in part to the shape of the underside of a user's foot. A formation with variations in thickness of any of the kinds outlined above may be so orientated that a variation in thickness occurs transversely of an article of footwear in which it is incorporated; for example the formation may be thicker near one side of the article of footwear than it is near the other side thereof. Alternatively, or in addition, the formation may be so orientated that the variation in thickness occurs lengthwise of the article of footwear.

An article of footwear may incorporate a single energy return formation, or it may incorporate two or more such formations, each disposed in a different part of the article; it is envisaged that one formation would usually be incorporated in the heel of an article of footwear and that any additional formation would be in the sole. If desired, however, a single formation could extend so as to be both in the heel and the sole. It must be understood, incidentally, that the terms heel and sole refer not only to clearly defined structures of an article of footwear but generally to those parts of an article of footwear which in use bear the load transmitted by a rear portion and forward portion respectively of a user's foot.

When an energy return system embodying a formation according to the present invention is in use and a load is applied to the system, the membrane or other resilient means yields resiliently and thus stores energy. The manner in which the resilient energy-storing means yields may differ from system to system. In the case of a substantially planar membrane, the application of a load to that system may- cause the membrane to adopt a wavy or locally undulating shape.

The membrane or other resilient means may be made of any suitable resilient material, preferred materials being rubber, synthetic rubber such as that marketed by Dupont under the trade mark "HYTREL" , and plastics materials such as soft polyurethane. If desired the resilient means may be formed integrally with adjacent parts of an article of footwear, or may be welded or bonded thereto.

The membrane and/or other components of the formation may be made as injection mouldings.

The invention will now be described in more detail with reference to the accompanying drawings which illustrate, somewhat schematically, various examples of ways in which the invention can be carried into effect. In the drawings:- Figure 1 is a side view of a sports shoe incorporating an energy return system according to the present invention,

Figure 2 is a plan view of a first embodiment of energy return formation for a system as shown in Figure 1,

Figure 3 is a view of the first formation on line III-III of Figure 2 when unstressed,

Figure 4 is similar to Figure 3 but shows the formation when stressed,

Figure 5 is a side view of a second embodiment,

Figure 6 is a section, on line VI-VI of Figure 5,

Figure 7 is a section on line VII-VII of Figures 6 and 8,

Figure 8 is a view similar to Figure 6 but of a third embodiment,

Figure 9 is a section one line IX-IX of Figure 8,

Figure 10 illustrates a moulded sheet from which a fourth embodiment, generally of the kind shown in Figures 2 to 4, may be formed by folding,

Figure 11 shows the sheet of Figure 10 folded to provide the fourth embodiment,

Figure 12 shows a fifth embodiment, similar to that of Figure 11, but in which two separate moulded sheets have been secured together adhesively,

Figure 13 illustrates a sixth embodiment, in which upper and lower supports of the formation are in the form of ribs following wavy lines,

Figure 14 is a section on line XIV-XIV of Figure 13,

Figure 15 is a section on line XV-XV of Figure 13,

Figure 16 shows a seventh embodiment, in- which upper and lower supports of the formations are in the form of ribs forming concentric circles,

Figure 17 is a section on line XVII-XVII of Figure 16, and

Figures 18, 19, 20 and 21 show four sections, such as on line A-A of Figure 3, illustrating some alternative support constructions.

Figure 1 illustrates somewhat diagrammatically a sports shoe 1 having an upper 2 and a combined sole and heel structure 3. A heel portion of that structure is formed with a through slot in which is housed a formation 4 of an energy return system.

The formation 4 may be a unitary moulding of rubber comprising (as shown in Figures 2 and 3) a membrane 5 interconnecting an array of cylindrical supports 6 on its upper surface and an array of similar cylindrical supports 7 on its lower surface. As shown in Figure 2, the upper supports 6 are disposed at the corners of a notional grid of squares, while the lower supports 7 are disposed at the corners of a similar notional grid of squares, the two grids being offset from each other so that each support, 6 or 7, of one array is aligned with the middle of a square disposition of four adjacent supports of the other array.

The lower supports 7 rest on a flat surface 8 of a lower portion of the sole and heel structure 3 while the upper supports 6 are engaged by a surface 9 of an upper portion of that structure. Those surfaces 8 and 9 are flat, substantially horizontal and parallel with each other. At least that portion of the structure 3 above the formation 4 is arranged to yield resiliently, so permitting the formation 4 to be loaded by someone wearing the shoe.

When the energy return system is unstressed the membrane 5 is flat, as shown in Figure 3. When a downwards load is applied to the system the membrane yields resiliently to assume an undulatory form as shown in Figure 4, the load applied to the formation being transmitted to the membrane by the downwardly-acting upper supports 6 and the upwardly-acting lower supports 7. Energy is thus stored in the distorted membrane, that energy being released by restoration of the resilient membrane to its flat condition when the load is removed.

Figures 5, 6 and 7 show an energy return formation in which an array of cylindrical upper supports 10 is provided as downwardly-extending projections of an upper plate member 11, and an array of cylindrical lower supports 12 is similarly provided as upwardly-extending projections of a lower plate member 13. The two plate members 11 and 13, comprising the supports 10 and 12, are each unitary mouldings of rigid construction. A flat membrane 14 of a flexible resilient material is sandwiched between the supports 10 and 12. As in the first embodiment described, the upper and lower supports are each arranged in square grid patterns, the upper and lower patterns being offset as seen in Figure 5. In use of this formation, the membrane 14 becomes distorted in a similar way to that illustrated by Figure 4.

A further feature of this second embodiment is piston-like stabilising assemblies which may be formed along opposite edge portions of the formation. These ensure that the rigid plate members 11 and 13 are constantly mated together to maintain the formation laterally rigid and prevent sideways collapse. Spaced locating pegs 15 extending downwardly from margins of the upper plate member 11 slide like pistons within corresponding tubular sockets 16, extending upwardly from margins of the lower plate member 13. The arrangement is illustrated on a larger scale in Figure 7. Such stabilising assemblies could of course be placed at any suitable position or positions in the formation. Upper end portions of the sockets 16 extend up through apertures in the membrane 14.

A similar construction to the one just described, and being a third embodiment of the invention, is shown in Figures 8 and 9. In a similar pattern to that shown in Figures 2 and 5, upper cylindrical supports 17 project down from a rigid upper plate member 18 and lower cylindrical supports 19 project up from a rigid lower plate member 20. A flexible and resilient flat membrane 21 is secured to be operative between the upper and lower supports 17 and 19. Along opposite margins of the two plate members 18 and 20, locating pegs 22 are arranged to slide vertically within tubular sockets 23, in piston-like assemblies as in the second embodiment and further illustrated in Figure 7. However, in this third embodiment a moulded member forming the membrane 21 also comprises upper and lower tubular projecting portions 24 and 25, respectively, forming sockets for location of the upper and lower supports 17 and 19. The rigid supports 17 and 19 restrain the flexible membrane 21 from pulling in, which would normally cause instability or inefficient energy return. When the formation is loaded the rigid supports keep the membrane in the same horizontal plane as it flexes, thereby utilising the natural memory of the membrane material.

Figures 10 and 11 illustrate construction of a formation similar to that shown in Figures 2 and 3 but in which a membrane 26 is constituted by two superimposed elements 27 and 28 integrally connected at one edge 29. The upper element 27 carries an array of upper supports 30 while the lower element 28 carries an array of lower supports 31. The formation is made by moulding a single sheet of flexible resilient material with supports on only one side thereof (Figure 10) and then folding it in two so that portions forming the upper and lower elements 27 and 28 bear against each other back-to-back. Alternatively, two separate elements 32 and 33 (Figure 12) may be adhesively secured together to give a similar result.

Figures 13, 14 and 15 illustrate another design of energy return formation. A unitary moulded body forms a membrane 34 which is provided on its upper surface with a plurality of integral upper supports in the form of elongate ribs 35. Each rib extends across the surface of the membrane along a wavy path, the ribs being spaced uniformly apart. On its lower surface the membrane is provided with a plurality of similarly shaped ribs 36 forming lower supports. The ribs 36 are also integral with the membrane and are offset laterally relative to the upper ribs 35 so that each lower rib 36 lies half way between two adjacent upper ribs 35. In use, when the system is loaded, the membrane 34 yields resiliently. The fact that the ribs 35 and 36 are of sinuous shape increases the stability of those ribs; if rectilinear ribs were used, there might be a tendency for at least some of them to yield individually and to become inclined to the membrane rather than to transmit the load fully to the membrane.

Figures 16 and 17 are views of yet another design. A membrane 37 is provided on its upper and lower surfaces with integral ribs 38 and 39 respectively. The upper ribs 38 constitute a set of concentric rings spaced uniformly apart; the lower ribs 39 also constitute a set of similar concentric rings, coaxial with the set constituted by the upper ribs 38. Each of the upper ribs 38, however, is radially equidistant from the two adjacent lower ribs 39.

Numerous other shapes and dispositions of supports are, of course, possible, and different areas of a single membrane may be provided with different forms and layouts of supports, as desired.

In each of the energy return systems just described, except the second and third embodiments (Figures 5 to 9) , the supports are formed integrally with the membrane. Such supports may be solid cylindrical (Figure 18) , tubular cylindrical (Figure 19) or some other suitable shape. In each instance, however, some or all of the supports may be formed separately from the membrane. They may be suitably secured to the membrane after formation of the membrane (e.g. a conical interconnection, Figure 20) or become secured in moulding the membrane (e.g. a T-head interconnection, Figure 21) . They may be mounted on an adjacent part or parts of an article of footwear or on a holder or holders fitted to the article of footwear.

Further, each of the formations described with reference to the drawings is of uniform vertical thickness; that is, the formation is designed to be accommodated between two planar, parallel surfaces of the footwear. It must be understood, however, that any of those formations can be modified so as to make it suitable to be accommodated between curved surfaces and/or between surfaces that are not spaced uniformly apart. To enable a formation to be accommodated between surfaces that are not spaced uniformly apart the supports may vary in height from one part of the intervening membrane to another.

It will be appreciated that the present invention can provide a wide range of possible designs of energy return systems, suitable for any of a wide range of articles of footwear but that an essential feature of each design is the provision of resilient energy-storing means which is operative between mutually offset supports and yields resiliently when a load is applied to the associated article of footwear.

Such energy return formations may be provided as "tablets" for insertion into a shoe as a separate item. In that way they may be replaceable, enabling a pair of shoes to be given different energy return characteristics for different uses by means of an interchangeable set of formations of varying performance.

Claims

1. In or for an article of footwear, an energy return formation presenting an array of downwardly-acting upper supports, an array of upwardly-acting lower supports which are offset from the upper supports, and resilient energy-storing means extending between adjacent upper and lower supports to yield resiliently upon a downwards load applied to the formation being transmitted thereto by the upper and lower supports.

2. An energy return formation according to claim 1, in which the upper and/or lower supports are of round, square or other compact cross-section.

3. An energy return formation according to claim 1, in which the upper and/or the lower supports are in the form of elongate ribs.

4. An energy return formation according to claim 3, in which the ribs extend along a wavy path.

5. An energy return formation according to claim 3, in which each rib extends along a circular or other - endless path, the ribs being concentric with one another.

6. An energy return formation according to claim 1, in which the energy-storing means comprises a resilient membrane extending laterally of the formation between the upper and lower supports.

7. An energy return formation according to claim 6, in which the membrane is flat when in an unstressed condition.

8. An energy return formation according to claim 6, in which the membrane and the upper and/or lower supports are formed as a unitary moulding of a resilient material.

9. An energy return formation according to claim 6, in which the membrane comprises a plurality of plate-like elements stacked together.

10. An energy return formation according to claim 9, in which two elements of the membrane have been provided by folding a single sheet of resilient material on to itself to form two layers.

11. An energy return formation according to claim 9, in which the membrane has been formed by securing together two or more stacked elements adhesively.

12. An energy return formation according to claim 6, in which the upper supports are provided by an upper rigid member, the lower supports are provided by a lower rigid member, and the resilient membrane is interposed between the upper and lower members.

13. An energy return formation according to claim 12, in which the rigid upper and lower members are furnished with interengaging elements .which co-operate as stabilising assemblies to prevent lateral collapse of the formation.

14. An energy return formation according to claim 13, in which the interengaging elements comprise locating pegs which are arranged to slide within tubular sockets as piston-like stabilising assemblies.

15. An energy return formation according to claim 12, in which a moulded member forming the resilient membrane comprises also upper and lower tubular projecting portions forming sockets which accommodate some at least of the upper and lower supports of the upper and lower members.