GB2487084A

GB2487084A - Shoe with cavities and connecting passageways in the sole

Info

Publication number: GB2487084A
Application number: GB201100263A
Authority: GB
Inventors: Mark Farndon
Original assignee: MADISON TRADING Ltd
Current assignee: MADISON TRADING Ltd
Priority date: 2011-01-07
Filing date: 2011-01-07
Publication date: 2012-07-11
Also published as: GB201100263D0

Abstract

A shoe, boot or sandal (1, fig 1) comprises an outsole assembly 2, a flexible upper 3 and a tongue 4 sewn inside the upper 3. The outsole assembly 2 comprises an outer sole 10 and a midsole 11. A sock 12 is fixed to the outsole assembly 2 by adhesive. A cavity 13 is defined by two depressions 13a and 13b, with further cavities 14, 15, 16 formed from depressions as the midsole and the outsole are bonded together. At least one cavity is positioned in the heel of the shoe, and at least one cavity in the forepart of the shoe. The cavities 13, 14, 15, 16 are connected by a passageway 17. The passageway extends along the locus (LP, fig. 3) of the instantaneous centre of pressure acting on the sole of the shoe during use. The application describes the manufacture of such footwear.

Description

The present invention relates to footwear, and is particularly concerned with structures for the soles of footwear such as boots, shoes and sandals, and methods of manufacturing such footwear and soles.

Shoes and boots are conventionally constructed from a flexible upper which covers the sides and top of the foot, and a sole which is attached at its edges to the upper, and extends beneath the foot of the wearer.

In order to reduce the shock loading on a wearer's ankles, knees and hips caused by walking or running on hard surfaces such as pavement, shoes have been developed with resilient soles made from plastics materials. In order to achieve an appreciable degree of cushioning, the soles must be made of relatively thick material. This however may have the disadvantage of lifting the wearer's foot away from the ground and increasing the possibility of injury due to sideways turning of the shoe if the ground is uneven.

US Patent 4577417 describes a shoe construction in which the sole of the shoe includes a first air chamber beneath the heel and a second air chamber beneath the forepart of the foot, the air chambers are being connected by a passageway extending along the medial side of the sole. The air chambers are positioned such that when the wearer takes a step and his heel strikes the ground, the first chamber is deformed (squashed) and air within the first chamber is compressed and transferred through the passageway to the second air chamber. As the forward part of the wearer's foot strikes the ground, the air in the second chamber is compressed, and as the wearer lifts his heel from the ground to take the next step, air passes from the second chamber into the first chamber.

As the shoe is lifted clear of the ground to take the next step, neither of the two chambers is compressed, and thus the chambers resume their unstressed shape and the air pressure equalises. Transferring air between the two air chambers absorbs some of the impact energy of the foot, and thus reduces shock loads.

The present invention seeks to provide a shoe construction which utilises deformable air chambers within the shoe sole to reduce shock loading, and by selectively positioning air passageways within the sole in relation to a line along which the instantaneous centre of pressure between the shoe and the ground moves during each step, provide a shoe sole which increases wearer comfort and promotes a smoother transition from heel to toe during each step thus increasing walking or running efficiency. Preferably, the passageways joining each linked pair of cavities follow the locus of the centre of pressure.

Laboratory measurements have shown that a typical person's walking gait involves the heel initially striking the ground at an outer part of the rear edge of the heel, and thereafter the area of the shoe in contact with the ground moves from the heel to the toe. In the area of contact, there is a distribution of pressure from the shoe to the ground which can be integrated to determine a point called the Centre of Pressure, through which the force of the shoe on the ground can be considered to act as a point force. As the area of contact moves forward during the stride, the centre of pressure moves along a path LP having five distinct sections. These sections are seen in Figure 4. First, the centre of pressure moves forwardly and inwardly across the heel towards the waist region, this section of the path being labelled A in the Figure. The centre of pressure then moves forwardly and outwardly along section B of the path towards the outer edge of the shoe at the waist region. At the waist region of the foot, the centre of pressure proceeds forwardly and inwardly along section C of the path. Beneath the central part of the forefoot, the centre of pressure proceeds substantially forwardly along section TJ of the path.

Section E shows the final forward and inward movement of the centre of pressure across the forepart of the shoe until toe-off occurs at an inner forward edge of the shoe sole.

"Medial" and "lateral" are here used to denote the sides of a foot, the medial side being the side which is adjacent the other foot when a person stands with feet together. The lateral side is the side furthest from the other foot, in that position. References to "outward" indicate the direction from the medial to the lateral side, and correspondingly references to

I

"inward" indicate the direction from the lateral to the medial. The area of narrowing between the heel and the forepart of the foot is referred to as the "waist region" of the sole.

S

Measurements of pressure may be made using a pressure plate such as an "RSScan Footscan" pressure plate, which is placed horizontally as a test subject walks or runs across the plate. The pressure plate makes instantaneous force or pressure measurements and calculates the position of the Centre of Pressure which the shoe exerts against the plate many times during the stride, as the subject's shoe first contacts the pressure plate at heel strike, until the shoe leaves the plate at toe-off. Typically, each test subject will make a number of passes over the pressure plate, and to accumulate sufficient data for a generalised Centre of Pressure locus to be calculated, data will be collected from a plurality of subjects. The pressure plate is linked to a computer to capture the data, "Gait 7.7" software preferably being used to capture the data and provide the computation resulting in the Centre of Pressure locus for each stride. The data may then be scaled to a standard shoe size and averaged to provide a "generic' locus for a plurality of subjects, as illustrated in Figure 4.

The present inventor believes that by providing air cavities and passageways within the sole of the shoe which follow the locus of the centre of pressure, the wearer's foot will be more effectively cushioned and a more efficient transition through the step will be achieved.

The locus of the centre of pressure may be affected by the external contours of the tread pattern of the shoe sole, and by the relative hardness of the materials of the various parts of the shoe sole. For a relatively smooth sole of substantially uniform hardness, a typical locus may be assumed. If the sole has asymmetric or elongate embossed tread pattern portions, biomechanical tests may be required to establish the locus of the centre of pressure for a typical wearer. When the locus has been established, the pattern of cavities and passageways which correspond to the tread pattern of the sole may then be determined such that the cavities, and the passageways joining adjacent cavities within the sole coincide with the locus.

In some embodiments, air chambers are positioned within the shoe sole assembly and embossments or protuberances are formed on the ground-engaging surface of the shoe sole at positions corresponding to the location of at least some of the air chambers.

Each protuberance of the sole may be formed with a corresponding air chamber. In some embodiments, an air chamber may be positioned so as to extend over an area of the shoe sole where a plurality of embossments or protuberances are formed. In other embodiments, an embossment or protuberance may have a corresponding air chamber covering only part of the area of the embossment.

In one particular embodiment, the heel part of a shoe sole is formed with four embossments arranged as a pair of inner and a pair of outer embossments, each pair having a forward and a rear embossment. The sole may be formed with a cavity extending over a generally "L"-shaped area corresponding to three of the embossments, namely the outer two embossments and the more forward of the inner two embossments. The inner rear embossment may be formed as a solid part of the sole, and may provide a stabilisation to the heel strike.

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1 is a side view of a shoe; Figure 2 is a sectional view of the shoe of Figure 1, taken in a longitudinal vertical plane; Figure 3 is an underneath view of the outer sole of the shoe, illustrating the locus of the instantaneous centre of the pressure; Figure 4 is a plan view of the outer sole showing the relationship between the air chambers and passages and the locus of the centre of pressure; Figure 5 is longitudinal section of the shoe sole assembly of Figure 3 taken along the line A-A;

B

Figures GA to GD are transverse sectional views of the shoe sole assembly of Figure 3, taken along the lines B-B, C-C, D-D and E-E, respectively, in Figure 3; Figure 7 is an exploded perspective view from above showing a sandal having a sole incorporating the teachings of the invention; Figure 8 is a perspective view from below of the sandal of Figure 7, showing the underside of the outer sole; and Figure 9 is a sectional view of the finished sandal, taken along the line IX-IX of Figure 8.

Referring to the drawings, Figure 1 illustrates in side view a shoe 1 according to the invention. The shoe comprises an outsole assembly 2, a flexible upper 3 and a tongue 4 sewn inside the upper 3 to cover an opening 5 in the forward part of the upper 3. A shoe lace 6 extends through eyelets formed in the upper 3 on either side of the opening 5 for fastening the shoe to the wearer's foot.

Figure 2 illustrates the internal structure of the shoe. The outsole assembly 2 comprises an outer sole and a midsole 11. In the structure shown, the lower edge of the upper 3 is turned inwardly around its perimeter, and is attached to a sock 12 by sewing, illustrated schematically at S. The sock 12 and the overlapping edges of the upper 3 are fixed to the outsole assembly 12 by adhesive.

In this embodiment, the midsole 11 is made by a compression moulding process and is bonded to the outer sole 10 by adhesive to form an airtight seal between the midsole 11 and outer sole 10. The outer sole 10 in this embodiment is moulded from natural or synthetic rubber, but may be formed of any other suitably durable and resilient material. In the embodiment shown, the under surface of the midsole 11 is formed with a depression l3a which overlies a corresponding depression l3b in the upper surface of the outer sole 10, so that when the two parts of the outsole assembly are bonded together, a cavity 13 is defined by the two depressions 13a and l3b. The upper surface of the outer sole 10 is formed with a number of further depressions 14 to 16, which form cavities when the midsole and outer sole are bonded together.

The cavities 13 to 16 are connected by narrower grooves 17 formed in the upper surface of the outer sole 10.

When a fabric sock 12 is used in the construction of the shoe, the conventional method of constructing the shoe is to sew together all of the parts which form the upper 3, and then sew the sock to the upper using a specialised sewing machine to form a "bag". The outsole assembly comprising the midsole and outer sole is prepared separately, and the shoe is finally brought together by placing the "bag" (the upper and the sock) over a foot-shaped last, and bonding the outsole assembly to the upper and sock using adhesive.

As an alternative to a fabric sock 12, a stiffer insole board, for example of a plastics material or cellulosic sheet material, may be used to overlie the midsole and the turned-in regions of the upper. In this kind of construction, the sections of the upper are first sewn together. The insole board and the upper are then placed on a last. Lower edge regions of the upper (the "lasting margin") are then drawn inwardly underneath the last, with the edge regions of the insole board positioned between the last and the lasting margin of the upper. The outsole assembly is then attached to the insole board and the lasting margin of the upper, using adhesive or possibly stitching. The shoe is then removed from the last.

The outsole assembly of the shoe according to the present invention comprises a midsole and an outer sole which are bonded together to form the outsole assembly. The outer sole is generally formed from a harder material than the midsole. In one embodiment, the undersurface of the midsole is flat, and the upper surface of the outer sole is formed with a number of depressions linked by grooves. When the midsole is bonded to the upper surface of the outer sole, the depressions and grooves are capped by the midsole so that the depressions form a number of cavities between the midsole and outer sole, and the grooves form passageways which link the cavities together.

The cavities and the grooves are preferably formed in the upper surface of the outer sole, but in some embodiments depressions and/or grooves may be formed either alternatively or additionally in the lower surface of the midsole. For example, depressions may be formed in the upper surface of the outer sole, and a number of grooves may be formed in the under surface of the midsole such that when the two sole parts are joined together, the under surface of the midsole caps the depressions to form cavities, and the upper surface of the outer sole caps the grooves to form passageways linking the cavities. Alternatively, depressions may be formed in the under surface of the midsole, and a number of grooves may be formed in the upper surface of the outer sole, the arrangement again being such that when the two sole parts are joined together, the depressions are closed to form cavities, and the grooves are closed to form passageways linking the cavities. In a further alternative, both the upper surface of the outer sole and the under surface of the midsole may be formed with depressions and/or grooves in corresponding positions which, when the outer sole and midsole are bonded together, form cavities and passageways connecting the cavities.

Figure 3 is an underneath view of a shoe sole, showing one example of a tread pattern for the shoe sole. The underside of the shoe sole includes four embossed areas or "pods" Hi, H2, H3 and H4 on the heel part of the shoe. The pods are generally shaped as rectangles with outwardly convex curved longer sides and straight shorter ends. At the rear outer part of the heel, pod Hl is arranged with the long axis of the pod inclined forwardly and outwardly. Pod H2 is arranged at the rear inner part of the heel, with its long axis inclined forwardly and inwardly. Pod H3 is arranged at the forward outer part of the heel, with its long axis inclined forwardly and outwardly, and pod H4 is arranged at the forward outer part of the heel, with its long axis inclined forwardly and inwardly.

As may be seen in Figure 3, the forepart of the sole in front of the waist region is provided with three elliptical pods Fl, F2 and F3. The pods are again generally shaped as rectangles with outwardly convex curved longer sides and straight shorter ends. Pod F2 is positioned under the ball of the foot, with its long axis inclined generally transversely to the sole.

Pod Fl is positioned behind pod F2, between the waist region and pod F2. Pod F3 is positioned at the toe end of the sole, in front of pod F2.

The locus of the instantaneous centre of pressure is shown as a line LP in Figures 3 and 4, Figure 4 illustrating the five sections A to E of the line LP discussed above. Figure 4 is a view of the shoe sole of Figure 3, and shows the outlines of cavities 13, 15, 16 and lEa formed between the outsole and the niidsole of the shoe.

In the example shown, at the toe end of the shoe cavity lEa generally corresponds in size, shape, position and orientation to the foremost pod F3.

Likewise, cavity 16 in the central region of the forepart of the shoe generally corresponds in size shape and position to the pod F2, and cavity 15 generally corresponds in size shape and position to the pod Fl.

Passageway l7c linking cavities 16 and lEa is positioned to follow the line LP adjacent the junction of regions D and E. Likewise, passageway 17b linking cavities 15 and 16 is positioned to follow the line LP in region ID. Through the waist region of the sole,

S

passageway 17a generally follows section 0 of the line LP.

In the heel part of the shoe, cavity 13 extends in a region extending across the front part of the heel and extending along the outer part of the rear of the heel, so that the pods Ill, 1-13 and H4 are positioned substantially within the area corresponding to the cavity 13. At the inner rear part of the heel, no cavity is provided beneath the pod H2. The absence of a cavity makes pod Hl comparatively stiff in relation to the other three pods of the heel, and improves stability of the shoe at heel strike. The stiffness of pod 1-12 may be adjusted by adjusting the hardness of the material of the outsole and/or midsole which underlies the pod 1-12.

Figure 5 is a longitudinal section of the sole assembly, showing the midsole 11 and the outer sole 10. The cavities lEa, 16, 15 and 13 are defined between the midsole 11 and the outer sole 10, and correspond in a location with the pods F3, F2, Fl and Hl, respectively. In Figure 5, a stop bar 1Gb extends into the cavity 16 from the outer sole 10, in order to limit the movement of the outer sole 10 towards the midsole 11. Likewise, in cavity 15, a stop bar l5b extends from the outer sole towards the midsole 11.

Figure GA is a transverse sectional view of the sole taken along the line B-B of Figure 3, in the frontal region of the sole. In this region, the outer sole 10 is bonded to the midsole 11 over the majority of the width of the sole, with only a small part of cavity 16a lying at this section.

Figure GB is a section along the line C-C, cutting partly through the cavity 15. Figure 6C is a sectional view along the line ID-fl of Figure 3, through the waist region of the sole, showing the passageway l7a linking cavities 15 and 13.

Figure GD is a section along the line E-E of Figure 3, at the heel part of the shoe showing the increased thickness of the midsole 11 at this region. The cavity 13 and parts of pods H3 and H4 are visible in this Figure.

To produce the sole illustrated in Figures 3 to 6, the pattern of pods on the sole is first determined, and the positions of the cavities are then chosen in relation to the pattern of pods. Thereafter, the position of the line LP may be determined either by experiment or through mathematical modelling. Once the position of the line LP has been determined, the positions of passageways 17 are then chosen so that the passageways follow the line LP and connect the cavities.

Midsoles and outsoles having the required pattern of pods, cavities and passageways may then be assembled into soles for shoes, boots or sandals and attached to appropriate uppers to form the finished footwear product.

Figure 7 is an exploded view of a sandal having a sole and a strap 40 to engage the wearer's foot. Other arrangements of straps may be used to secure the sole 20 to the wearer's foot, but the particular arrangement has been found convenient for an easily-donned sandal. The sole 20 comprises an outsole 21 and an insole 22, which in the finished sandal will be bonded together. The upper surface of the outsole 21 has at its heel part two cavities 23 and 24 joined by a passageway 25 extending along the line followed by the instantaneous centre of pressure LP. In its forepart, the upper surface of the outsole 21 is formed with three cavities 26, 27 and 28.

A passageway 29 joins the cavity 24 of the heel to the cavity 26 of the forepart, the passageway 29 again following the line LP. Between cavities 26 and 27, a passageway 30 is formed following the line LP and finally a passageway 31 following the line LP joins cavity 27 to cavity 28 at the toe end of the sandal.

The passageways may be of the same depth as the cavities, such as passageway 31 and cavity 28.

Alternatively, as can be seen by comparing passageway and cavity 27, the passageway may be reduced in depth as compared to the cavity. When the outsole 21 and the midsole 22 are bonded together, the undersurface of the midsole caps the cavities and passageways to form a fluid-tight space.

Figure 8 is a view of the underside of the sole of the sandal, showing embossed gripping regions or pods provided on the underside of the outsole 21 in positions corresponding to the positions of the cavities 23, 24 and 26 to 28.

Figure 9 is a sectional view taken along the line IX-IX of Figure 8. The section plane passes through the pods 43, 44, 46 and 47 and their corresponding cavities 23, 24, 26 and 27, but not through pod 48 and its cavity 28.

In this embodiment, as can be seen in Figures 7 and 9, the cavities 26 and 27 are provided with respective stop bars 26b and 27b, the bars extending generally transversely across the sole and within the respective cavity. When the wearer places pressure on the pods 46 and 47, the outer sole is pressed towards the midsole, until the stop bar 27b contact the midsole to limit the relative movement of the sole parts.

Limiting the relative movement can increase the life of the sole by preventing cracking and breaking of the outsole round the edges of the cavities, by limiting the deformation of the sole in these areas. The stop bars 26b and 27b also provide a level of stability when the pod is deformed.

Claims

Claims: 1. An item of footwear comprising an upper and a sole, the sole having a first air cavity beneath the heel part of the sole and a second air cavity beneath the forepart of the sole, the first and second cavities being joined by a passageway extending along the locus of the instantaneous centre of pressure between the shoe and the ground for a typical wearer.
2. An item of footwear according to claim 1, wherein the sole comprises an outsole having an upper surface and a lower surface and a midsole having an upper surface and a lower surface, the lower surface of the midsole being bonded to the upper surface of the outsole, and wherein at least one of the first and second cavities is formed by recesses in the upper surface of the outsole and is closed by the undersurface of the midsole.
3. An item of footwear according to claim 1, wherein the sole comprises an outsole having an upper surface and a lower surface and a midsole having an upper surface and a lower surface, the lower surface of theSmidsole being bonded to the upper surface of the outsole, and wherein at least one of the first and second cavities is formed by recesses in the lower surface of the midsole and is closed by the upper surface of the outsole.
4. An item of footwear according to any preceding claim, wherein the sole comprises an outsole having an upper surface and a lower surface and a midsole having an upper surface and a lower surface, the lower surface of the midsole being bonded to the upper surface of the outsole, and wherein the passageways are formed by recesses in the upper surface of the outsole and are closed by the undersurface of the midsole.
5. An. item of footwear according to any of claims 1 to 3, wherein the sole comprises an outsole having an upper surface and a lower surface and a midsole having an upper surface and a lower surface, the lower surface of the midsole being bonded to the upper surface of the outsole, and wherein the passageways are formed by recesses in the lower surface of the midsole and are closed by the upper surface of the outsole.
6. An item of footwear according to any preceding claim, wherein the outsole comprises an embossment on its underside for gripping engagement with the ground in use, the embossment being positioned so as to correspond with the position of one of the first or second cavities.
7. An item of footwear according to claim 6, wherein the heel part of the sole comprises inner and outer embossments positioned substantially side-by-side, and wherein the first cavity is formed in the heel part of the shoe in a position corresponding to the outer of the two embossments.
8. An item of footwear according to claim 6 or claim 7, wherein the heel part of the sole is formed with four embossments arranged as a pair of inner and a pair of outer embossments, each pair having a forward and a rear embossment, and wherein the sole is formed with a cavity extending over a generally "L"-shaped area corresponding to the pair of outer embossments and the forward inner embossment.S
9. An item of footwear according to claim 8, wherein the inner rear embossment is formed as a solid part of the sole.
10. An item of footwear according to any preceding claim, wherein the forepart of the sole comprises a second cavity and one or more further cavities, the second cavity and the further cavity or cavities being linked by passageways.
11. An item of footwear according to claim 10, wherein the forepart of the outsole comprises an embossment on its underside positioned so as to correspond with the position of the second cavity.
12. An item of footwear according to claim 10 or claim 11, wherein two further cavities are formed in the forepart of the sole.
13. An item of footwear according to claim 12, wherein the forepart of the outsole is formed with two further embossments on its underside positioned so as to correspond with the positions of the two furtherScavities.
14. An item of footwear according to any preceeding claim, wherein the item of footwear is a shoe, boot or sandal.
15. An outsole assembly for an item of footwear, according to any preceding claim.
16. An outer sole for an outsole assembly according to claim 15, wherein the outer sole has an upper surface, and at least two recesses formed in the upper surface of the outer sole and joined by a groove, and wherein the outer sole is adapted to be attached to a midsole to sealingly close the recesses and groove so as to form to cavities linked by a passageway.
17. A method of manufacturing an item of footwear comprising a sole and an upper, the method comprising the steps of: determining a tread pattern for the sole; determining the locus of the instantaneous centre of pressure on the sole for a typical wearer; determining the position of at least two cavities and a passageway within the sole, such that the cavities are joined by the passageway and the passageway follows the determined locus, forming a sole having the tread pattern and including cavities and a passageway in the determined positions; and attaching the sole to an upper to form an item of footwear.
18. A method according to claim 17, wherein the step of determining the locus of the instantaneous centre of pressure on the sole for a typical wearer comprises using a predetermined locus.
19. A method according to claim 17, wherein the step of determining the locus of the instantaneous centre of pressure on the sole for a typical wearer comprises measuring instantaneous pressures on the sole and calculating the locus from the pressure measurements.
20. A method according to claim 19, wherein the predetermined locus is the mean of a plurality of test results.
21. A method of manufacturing an outsole assembly for an item of footwear comprising a sole and an upper, the method comprising the steps of: determining a tread pattern for the sole; determining the locus of the instantaneous centre of pressure on the sole for a typical wearer; determining the position of at least two cavities and a passageway within the sole, such that the cavities are joined by the passageway and the passageway follows the determined locus; forming an outsole assembly having the tread pattern and including cavities and a passageway in the determined positions.
22. An item of footwear, substantially as herein described with reference to Figure 1, Figure 2 or Figures 7 to 9 of the accompanying drawings.
23. An outsole assembly for an item of footwear, substantially as herein described with reference to Figure 2, Figure 3, Figures 4 to 6, or Figures 7 to 9 of the accompanying drawings.
24. An outer sole for an outsole assembly for an itemSof footwear, substantially as herein described with reference to Figure 2, Figure 3, Figures 4 to 6, or Figures 7 to 9 of the accompanying drawings
25. A method of manufacturing an item of footwear, substantially as herein described.