US20210186143A1 - Modular insert system for shoe soles - Google Patents

Abstract

A support customising system is described for a sole of a shoe. The sole includes a relatively soft, resilient midsole and an a harder outsole. Hard insert elements are provided for inserting into vertical cavities in the midsole. By varying the hardnesses of different inserts in different vertical cavities, a precisely-tunable pronation control effect on the wearer's gait can be effected. First-order, second-order and third-order pronation control effects are described. Measures are provided for improving the accuracy of the proprioceptive (sensory motoric) effect on the wearer's foot, for example by limiting the ingress of dirt or water.

Description

TECHNICAL FIELD OF THE INVENTION
• The present invention relates to soles for articles of footwear, in particular footwear for correcting, supporting or accommodating the gait of the wearer.
BACKGROUND OF THE INVENTION
• In addition to providing general support for the wearer's feet while walking or running, shoe soles can be manufactured such that the degree of support for the foot differs between different regions of the sole. Thus the material of the heel region, for example, which experiences the greatest impact forces, is often manufactured to provide greatest impact cushioning effect. The desired variation in support may be achieved for example by varying mechanical properties of the material of the sole, such as the shape, thickness, density, hardness and flexural characteristics. In this way, the sole may be manufactured so as to provide optimum support for the typical wearer's feet. Since gait characteristics vary significantly from person to person, footwear manufacturers design the soles of their products to cater for a broad range of gait types, based around a putative norm. Soles may also be configured to suit different types of use. For example, soles may be configured for sprinting, long-distance running, playing particular sports such as golf or tennis or cross-country skiing, or for casual wear. Running shoes require different sole configurations for different distances, and for different types of terrain.
• The wearer is therefore obliged either to settle for a sole which will cover a wide range of uses, but will not be well configured for any of those uses, or he may purchase different footwear for different uses; different shoes for road-running and for cross-country running, for example, or different shoes for different distances.
• Specialist soles are also available which are configured to accommodate or correct particular types of gait, such as over-pronation or supination. Shoes are also available with soles which are customised to a particular combination of gait-type, or sport, or use. It is possible to have soles customised for a particular person, or even for a particular foot. However, bespoke soles are expensive, and the present invention is concerned primarily with soles for footwear which can be manufactured and distributed in significant numbers as a commercial retail product.
PRIOR ART
• It has been suggested to provide a certain customizability of the support provided to a wearer's foot by means of an orthotic insole, laid on top of the integral sole of a shoe.
• Such insoles may incorporate regions of different support, which are arranged to suit the particular use or gait-type. The hardness of the regions may be customised by exchanging portions of the orthotic, for example. Such a customisable orthotic is known from EP2383952, in which a shaped piece of the orthotic can be exchanged for a similarly-shaped piece having a different hardness. The orthotic described in this document thus provides a limited customizability of the support which is provided by the insole.
• WO2016092353, from the same inventors as the present invention, describes a sole customising system in which hard inserts are located in cavities in the midsole. The application does not address the problem of ensuring constant and accurate sensory-motoric stimulus (see below), but nevertheless proposes an arrangement which could potentially offer a solution in that the inserts can be inserted into the cavities from the top, so that the cavity bottoms are closed by the outsole.
• EP1352579 describes a midsole comprising regions of different hardnesses, so that the midsole can be customised for a particular wearer. The assembled portions of the midsole may be formed into a continuous moulding, in which case the customised sole is no longer customisable. Alternatively, the assembled portions can remain as discrete components of the sole, in which case the mechanical integrity of the sole as a whole is greatly reduced.
• DE20320091 describes an adaptable insert which affords a limited customizability of the support provided at a particular region of the sole. The insert is introduced from the medial side of the sole (ie left-hand side of a right shoe or right-hand side of a left shoe) or the lateral side of the sole (ie right-hand side of a right shoe or left-hand side of a left shoe), and is held in place using a clip. The insert also includes vertical hexagonal-shaped holes into which can be inserted hexagonal pegs of a particular hardness. In this way, the effective hardness of the insert can be varied by inserting pegs which are harder than the material of the insert, which gives the wearer some control over the degree of support provided at that particular region of the sole when the insert is located in position. The midsole is provided with a wide horizontal cavity, open to one side, into which the insert can be pushed. The presence of a wide cavity reduces the overall mechanical integrity of the sole, even with the insert in place, and provides a path for water and dirt to enter the sole, and to work their way deep within the sole. The presence of the midsole material above and below the cavity means that the effectiveness of the lateral insert is reduced, in that the amount of vertical support it provides is reduced, and the total amount of vertical support provided may the sole in the region of the insert can be less accurately defined. Over time, the material of the midsole above and below the cavity, and the material of the insert element surrounding the pegs, will lose elasticity and resilience due to the repeated compression during the gait cycle. Such insert elements are typically positioned in regions of the sole where greater support is required, which means that the repeated compression, and the consequent crushing of the insert material and the midsole material above and below the insert, will be particularly susceptible to degradation, and thereby shorten the wearable life of the shoe.
• It is also important for gait-correcting insert elements to retain a constant proprioceptive effect and to remain secured in the sole. If an insert works loose, or becomes plastically compressed, or if it is contaminated by ingress of dirt or water, the customised proprioceptive pressure effect of the insert will be altered.
BRIEF DESCRIPTION OF THE INVENTION
• The invention described in this application seeks to overcome at least some of the above and other disadvantages inherent in the prior art. In particular, the invention aims to provide a customisable article of footwear according toclaim1, a method according toclaim23 and a method according to claim25. Further variants are defined in the dependent claims.
• A support customising system is described below for the sole of a shoe or other article of footwear. The sole comprises a relatively soft, resilient midsole and (optionally) a harder outsole. Insert elements of various hardnesses are provided for inserting into vertical cavities in the midsole. By customising the hardnesses of different inserts in different vertical cavities, a precisely-tunable pronation control effect on the wearer's gait can be effected. First-order, second-order and third-order pronation control effects are described.
• The invention and its advantages will further be explained in the following detailed description, together with illustrations of example embodiments and implementations given in the accompanying drawings. Note that the drawings are intended merely as illustrations of embodiments of the invention, and are not to be construed as limiting the scope of the invention. Where the same reference numerals are used in different drawings, these reference numerals are intended to refer to the same or corresponding features. However, the use of different reference numerals should not in itself be taken as an indication of any particular difference between the referenced features. In this description the terms hardness and durometer are used interchangeably, and numerical hardness values refer to the Shore A hardness scale.
• FIG. 1ashows in side view a schematic cross-section of an example shoe employing a support-customising system of proprioception-enhancing inserts.
• FIG. 1bshows in isometric view an example of support adjustment inserts for use in the support customising system ofFIG. 1a.
• FIG. 2 shows a schematic plan view, viewed from below, of a first example sole employing a support customising system.
• FIGS. 3 to 8 show cross-sectional schematic views of various example geometries of proprioception-enhancing inserts.
• FIGS. 9 to 11 show cross-sectional views of various example arrangements of proprioception-enhancing inserts in a sole.
• FIGS. 12 and 13 show transverse cross-sectional views of two example arrangements of proprioception-enhancing inserts.
• FIG. 14 shows a longitudinal cross-sectional view of an example arrangement of proprioception-enhancing inserts.
• FIG. 15 shows a transverse cross-sectional view of an example of an insert-retention arrangement.
• FIGS. 16 to 24 show cross-sectional views of example geometries of proprioception-enhancing inserts.
• FIGS. 25 to 27 show cross-sectional views of example sealing and retention arrangements of proprioception-enhancing inserts.
• FIGS. 28 to 30 show cross-sectional views of example cavities with linings.
• FIGS. 31 to 33 show the cavities ofFIGS. 28 to 30 with examples of inserts.
• FIG. 34 shows a cross-sectional view of a (sperical or cylindrical) cavity and insert having a circular cross-section.
• FIGS. 35 and 36 show cross-sectional and plan views of an example of a lined cavity with a retaining protrusion.
• FIG. 37 shows a cross-sectional view of an insert having a broaded distal end for aiding retention.
DETAILED DESCRIPTION OF THE INVENTION
• An example of a support customising system is illustrated inFIGS. 1aand 1b.FIG. 1adepicts a schematic cross-section of a shoe with a sole1 comprising anoutsole4,aFF midsole3, bonded to theoutsole4, and a liner orinsole6 laid on theupper surface7 of themidsole3. Themidsole3 may be made of a resilient material, for example an elastomer such as ethyl vinyl acetate (EVA) or other suitable material. Theoutsole4 may for example be constructed from a hard, resilient elastomeric material such as rubber/polyurethane, and may have a hardness which is greater than that of themidsole3, at least at the ground-facing surface of theoutsole4. Alternatively, themidsole3 andoutsole4 may comprise the same or similar materials, or may be contiguous, homogenous regions of the same moulded shape. The liner orinsole6 may be of relatively thin and/or softer material and serves to provide a comfortable surface for the sole of the wearer's foot. The liner orinsole6 may be removed to expose theupper surface7 of themidsole3.
• The example sole1 illustrated inFIG. 1ais provided with a plurality (six are shown) ofvertical cavities2, each of which opens out through theoutsole4 and extends up towards theupper surface7 of themidsole3 along avertical axis8. Themidsole3, apart from the holes (cavities2) which are formed in it, may be constructed of continuous material, in order to ensure the mechanical integrity of the sole as a whole. The vertical direction is understood in this text to be the vertical direction when the shoe is standing flat on level ground. Thevertical axis8 is thus substantially orthogonal to thegeneral plane9 of the sole1, which is taken to be generally parallel to the upper, foot-facingsurface7 of themidsole3 and/or to the lower surface of theoutsole4, at least in the heel and/ormidfoot regions13,14 of the sole1. The sole1 illustrated inFIG. 1ahas parallel upper and lower surfaces for clarity. In practice, the heel area of the sole may be thicker than the forefoot area (‘positive drop’), or vice versa (‘negative drop’), and/or the mid-foot zone may be thicker than both the heel and forefoot regions, for example.
• The terms lower and upper used in this description are also defined in terms of thevertical axis8. Note that the term vertical is used in this text to denote a general rather than a precise orientation of thevertical cavities2, and includes orientations which differ by up to 15 degrees, or alternatively even up to 40 degrees from thevertical axis8 shown inFIG. 1a.
• While only six cavities/inserts are shown in particular cross-section ofFIG. 1a, all in the heel and mid-foot parts of the sole, it should be understood that the sole may also comprise similar cavities/inserts in forward regions of the sole.
• FIG. 1bshows a set of inserts or plugs5, also referred to in this description as support adjustment inserts or proprioception-enhancing inserts, which are designed for insertion into thecavities2 in themidsole3. In the example shown inFIGS. 1aand 1b, theinserts5 may be inserted into thecavities2 through openings in theoutsole4. Inserting the inserts from below has the advantage that the insertion openings are more readily accessible than if they are inserted from above. However, as discussed below, inserting the inserts through theoutsole4 renders the inserts liable to damage by over-compression (for example if the wearer steps on a stone) or by incursion of dirt or water.
• Theinserts5 may also be made of an elastomeric material, for example, and they may have different hardnesses from themidsole3 and/or from one another. Some of theinserts5 may have substantially the same hardness as the material of themidsole3, in order to provide a null support adjustment at aparticular cavity2. It is also possible to provideinserts5 with lower hardnesses than themidsole3; this may for example be useful for providing a negative support adjustment in a particular region of the sole1 by reducing the average hardness of the region by inserting one ormore inserts5 which are softer than the material of the surroundingmidsole3.
• The hardnesses of theinserts5 may be selected from a set of predetermined hardnesses. For example, a pair of shoes having soles such as that illustrated inFIG. 1amay be purchased with a set ofinserts5 similar to those shown inFIG. 1b, with multiple alternative inserts of different hardnesses available for insertion into each cavity, and with each insert having one of a predetermined selection of hardnesses. There may bemore inserts5 in the set than there arecavities2 in the sole1. Themidsole3 may have a hardness in the range 30 to 70 Shore, or 45 to 60 Shore, for example, and the supplied set ofinserts5 may include some inserts having a hardness of 50 Shore, some of 60 Shore, some of 70 Shore, some of 80, 90 or even 100 Shore, for example.Different inserts5 of different hardnesses may then be fitted into thecavities2 provided, so as to achieve the desired local support hardness at each cavity location and collectively in each region of the sole1 provided withcavities2. If the midsole has a first durometer, then the set of inserts from which inserts can be selected for insertion into the cavities may include inserts, each of which may have one of a predetermined plurality of durometers. The plurality of durometers may include durometers which differ from each other by between 5 and 20 Shore, including a durometer which is greater than the first durometer by between 5 and 40 Shore. As will be discussed below, the plurality of durometers may include a durometer which is the same as the first durometer and/or one or more durometers which are less than the first durometer. The first durometer of themidsole3 may be constant for all regions of themidsole3, or it may vary between regions of themidsole3. In the latter case, the first durometer may either be taken to be an average durometer of themidsole3 or a local durometer of a particular region of themidsole3.
• When the wearer puts weight on the sole, for example while walking, theinserts5 which are harder than the surrounding midsole material serve to transfer a force from between the ground and the wearer's foot which is greater than that transferred by the surrounding midsole material. Each of these harder inserts thereby provides increased support for the wearer's foot at the location in the sole at which it is inserted. Because theinserts5 each have one of a predetermined set of hardnesses, at least in the vertical direction, and because they extend along substantially the wholevertical depth11 of the sole1, or at least substantially thewhole depth11 of themidsole3, the net vertical hardness of the sole1 at the location of eachcavity2 is determined exclusively, or in a great majority, by the hardness of theparticular insert5. The hardness of theoutsole4, if it is different from the hardness of theinsert5, may also contribute an effect to the net vertical hardness of the sole1 at that location, but the contribution may be small, particularly if theoutsole4 is thin and/or the hardness difference between theoutsole4 and theinsert5 is small. Similarly, the contribution of theinsole6 or any minor part of the midsole which extends above or below theinsert5 when theinsert5 is inserted, will also have only a small effect on the net vertical hardness of the sole1 at the particular cavity. The term net vertical hardness is used here to indicate a measure of the compressibility and resilience of the sole in an approximately vertical direction (ie as measured along the vertical axis8). The net vertical hardness at a particular location may be represented or measured for example using the 25% compressive strength measurement at the location. This measure may be used, for example, where the inserts are 50% or less than the thickness of the sole at the location.
• For example, the 25% compressive strength (the pressure required to compress the sole thickness by 25%) of the sole at the location of a cavity containing an insert. An insert may be considered to have a proprioceptive effect if the durometer of the insert is such that the 25% compressive strength of the sole at its location is at least 50% greater than the 25% compressive strength of the surrounding sole adjacent to the insert/cavity. The presence or absence of a proprioceptive insert may be determined using a test as follows:
• The pointwise compressive strength of the sole at a particular location can be measured by vertically compressing the sole between a small upper plate, having a predetermined area of for example between 2 and 4 cm2, placed directly over the region of the sole being measured, and a larger lower plate, placed directly beneath the region of the sole being measured and beneath the lower surface of the lower surface of the sole (ie the lower surface of the insert and the outsole if present). The plates may be moved together so as to compress the sole vertically to a compression of 25% of the thickness of the sole (reduce the distance between upper and lower plates by 25%). The pressure which must be applied to the upper plate to achieve the 25% compression can be taken as a measure of the compressive strength of the sole at that location.
• If the 25% compressive strength of the sole with the insert is at least 50% greater than the 25% compressive strength of the adjacent sole material alone, then a significant proprioceptive effect is said to be present.
• Where an insert occupies at least half the thickness of the sole at a particular location, the propioceptive effect may be considered to be present when the durometer of the insert is at least 5 Shore A greater, or optionally 10 Shore A greater, than the durometer of the surrounding midsole.
• Thevertical cavities2 and theinserts5 shown in the example ofFIGS. 1aand 1bhave substantially parallel vertical side-walls. Thecavities2 may thus have a horizontal cross-section which is substantially constant along theirlength11, for example, or they may have a tapering cross-section, any other shape which allows them to be fitted into thecavities2 and/or subsequently removed for exchange. The horizontal cross-section of thecavities2 and inserts5 may be of any regular shape, such as circular, oval, ovoid, hexagonal, triangular, square or rectangular, or it may have an irregular shape. Theinserts5 andcavities2 are advantageously dimensioned such that it is possible to fit two or more cavities/inserts into a particular gait control region of the sole1, as will be discussed below. In this respect the cavities and inserts5 may be formed with a horizontal cross-section which has a largest transverse dimension of between 5 mm and 50 mm across, for example, or preferably between 10 mm and 30 mm.
• Because theinserts5 are oriented substantially vertically in themidsole3, and because they have relatively small lateral dimensions,multiple inserts5 andcavities2 can be located in a particular region of the sole1 in order to adjust the net vertical hardness of sole with a fine resolution. Thus, a pronation control zone in theforefoot area12 of the sole1 may incorporate multiple (eg three to ten inserts), for example, each with a hardness suitable for the pronation control requirement of the wearer. The hardnesses of the three to teninserts5 may be the same, or they may be graded. For example, the hardnesses of the inserts may be increased from therear-most insert5 to theforemost insert5.
• The discussion above has related primarily to theinserts5 andcavities2 of a single shoe. In a pair of shoes, theinserts5 andcavities2 may similarly be made so that thesame inserts5 can be used in thecavities2 of either shoe. The support customising system may be arranged such that, multiple pairs of shoes can share the same set of support adjustment inserts5.
• The use of multiple,interchangeable inserts5 having different hardnesses means that the support provided by the sole1 can be finely tuned to the needs of the wearer. The support may be differently tuned between the left shoe and right shoe, betweendifferent regions12,13,14 of one sole1, or even within the same region of the sole1.
• FIG. 2 shows a plan view of a shoe sole1 similar to the sole1 shown inFIG. 1a, and shows in more detail how the support adjustment inserts5 can be arranged in themidsole3 to achieve a customised support, for example as an aid to gait correction for the wearer.
• FIG. 2 shows themidsole3 of a left shoe, viewed from below, but it will be understood that the following description applies equally to a corresponding right shoe, although the arrangement ofinserts5 may be different between the left and right shoes.
• In the example configuration ofFIG. 2, the sole1 comprises aheel region19, a heelmedial region21, aheel lateral region22, aforefoot lateral region23, ametatarsal region24 and a forefoot medial region25. These regions are merely examples—other regions may be chosen. If there aremultiple inserts5 in each region, as shown, the support offered by the region as a whole can be adjusted precisely by including individual inserts having different durometers—either to give an overall average hardness which is equivalent to an intermediate durometer value between the available values of the available inserts, or to give a graded support across the region.
• Left and right feet naturally have slightly different pronation styles, due to the natural asymmetry in the person's posture and due to neurological effects which gives rise to asymmetries in gross motor control, reflected in the person's posture and gait. However, the characteristics of the landingportion19 of the heel region should preferably be the same for left and right shoes.
• Because theinserts5 of a particular region, or of multiple regions of the sole, may have the same cross-sectional shape, theinserts5 may be made interchangeable between allcavities2 of a particular region or between allcavities2 of the sole. In this case many different configurations of the support offered by the sole can be achieved with a relatively modest number ofinserts5.
• Eachinsert5 may be formed as a single contiguous piece of material, or it may be formed from two or more constituent pieces. It may be solid, for example to assure its rigidity, or it may be hollow, for example to cut down on shoe weight and material costs. It may be open at one or both ends, and it may have openings in its side wall(s).
• Also illustrated inFIG. 2 is anideal gait line20, also known as the stability axis or “S-line”, which indicates approximately how the wearer's foot should pronate during its heel-to-toe contact (gait cycle) with the ground. Theexample regions19,21,22,23,24 are identified only approximately, and are used to illustrate howinserts5 in the various regions can be used for controlling the wearer's gait.
• Themultiple cavities2 may advantageously have the same size and shape, as illustrated inFIG. 2. Theinserts5 of a particular set, even if they have different hardnesses, may also have the same size and shape, so thatmultiple inserts5 of different hardnesses can be interchangeably fitted into eachcavity2, and so that aparticular insert5 can be fitted intomultiple cavities2. Thehind-most heel part19 of themidsole3 inFIG. 2 is shown without anyinserts5 in this example. There may be instances when it may be useful to be able to adjust the hardness of thishind-most region19, but the illustrated example is designed to show how the support adjustment inserts5 can be used for pronation/supination control, and thehindmost region19 of themidsole3 serves primarily to cushion and control the landing impact of the heel on the ground and the initial forward motion of the foot.
• Medial andlateral control regions21 and22 can be used to control the amount of pronation during the initial phase of the gait cycle (ie following initial heel impact). By judicious choice of the hardnesses of theinserts5₁of themedial region21 and the hardnesses of theinserts5₁and5₂of the medial21 and lateral22 control regions, it is possible to influence the degree of pronation of the foot around the stability “S-line”20. Furthermore, the use ofinserts5 of graded hardnesses in a particular region permits a second-order control, in which not only the amount of pronation can be controlled, but also the rate of change of pronation with respect to the forward motion of the foot during the sole's contact with the ground when walking or running. Taking the six medial control inserts5₁illustrated inFIG. 2 as an example, a first-order pronation control can be obtained by selecting the hardness of the threeinserts5₂relative to the hardness ofmidsole3 and/or of the medial control inserts5₁. Harder lateral inserts5₂will encourage greater pronation, softer lateral inserts5₂will promote pronation less. However, by varying the difference between the durometers of the lateral inserts5₂, it is possible to achieve a second-order control effect. If the hardness difference between inserts along the heel to toe direction is large, for example (ie the rear-mostlateral insert5₂is much harder than the forward-mostlateral insert5₂, then the rate of pronation with respect to the foot's forward motion is greater. This means that the pronation occurs during a shorter time, when considered as proportion of the total contact time with the ground. On the other hand, if the hardness of theinserts5₂varies little along the heel to toe direction, then the pronation-enhancing effect with respect to the foot's forward motion will be less. If the foremostlateral insert5₂is harder than therear-most insert5₂, then this will act to reduce the rate of pronation.
• The lateral andmedial inserts5₁and5₂can further be used to achieve a third-order control effect, in that inserts can be selected to vary the rate of pronation. If thelateral control region22 is provided with more cavities and inserts5₂, (say five inserts in a line running parallel to the heel-toe axis, for example), then the hardnesses of the fivelateral inserts5₂can be chosen so as to vary the rate pronation along the heel-to axis. Thus, by being able to select the hardnesses of the lateral inserts5₂it is possible not only to vary the amount of pronation (first-order effect), but also to vary the rate at which pronation occurs (second order effect) and the axial variation in the rate of pronation (third-order effect).
• By using many cavities/inserts, it is possible to vary the pronation/supination control with a fine resolution, and in many different ways. For example, it is possible to take set the hardness of theinserts5 to take account of individual bones or bone groups in the foot. Excessive calcaneal/talar tilt can be compensated for, for example, while minimising the effect on the metatarsal or forefoot regions.
• The control effects described above in relation to theinterchangeable inserts5₂of thelateral region22 also apply to the other illustrated regions inFIG. 2; themedial control region21 with its multiple medial control inserts5₁, and theforefoot control regions23 and25, with their forefoot control inserts5₃and5₅. A singlemid-foot control insert5₄is illustrated inmidfoot control region24, which may be included in the midfoot/metatarsal region to discourage the wearer's arch from sinking. The sole1 may comprise such asingle midfoot insert24 on its own or in combination with one or more other inserts, as shown inFIG. 2, for example.
• As a consequence of such finely-adjustable and adaptable gait control, it is possible to improve the wearer's gait and straighten the wearer's axial skeleton, which not only has beneficial effects for the wearer, but also promotes even wear on theoutsoles4 and therefore extends the life of the shoes.
• Furthermore, if the individual inserts are replaceable, then the soles can be “tuned” for different uses, or for different wearers, or as the shoes age, or as the wearer's gait changes.
• The following examples illustrate the insert hardnesses which could be chosen for different gait control purposes. The examples are based on a sole configuration similar to that shown inFIG. 2, and the hardnesses given are relative to an example midsole material of hardness 50 Shore. Where different inserts hardnesses are listed for a particular region, these are listed on the order from rear-most to foremost).
Example 1: For Correcting a Slight Supination
• Lateral control region22: 50 Shore, 60 Shore, 60 Shore
• Medial control region21: all 50 Shore or less
• Forefoot lateral control region23: all 60 Shore
Example 2: For Correcting a Delayed Overpronation
• Lateral control region22: all 50 Shore (no correction)
• Medial control region21: 50, 60, 70, 80, 80, 60 Shore
• Forefoot lateral control region23: all 60 Shore
Example 3: For Correcting Severe General Overpronation
• Lateral control region22: 50, 50, 60 Shore
• Medial control region21: 70, 80, 90, 80, 70, 60 Shore
• Forefoot lateral control region23: all 60 Shore
Example 4: For Correcting Early, Slight Overpronation
• Lateral control region22: 50, 50, 60 Shore
• Medial control region21: 70, 60, 50, 50, 50, 50 Shore
• Forefoot lateral control region23: 70, 60, 50, 50, 50 Shore
Example 5: For Correcting Delayed, Slight Overpronation
• Lateral control region22: all 50 Shore (no correction)
• Medial control region21: 50, 50, 60, 60, 70, 70 Shore
• Forefoot lateral control region23: all 50 Shore (no correction)
• The sole ofFIG. 2 also shows how a stiffeningplate10 may optionally be included to maintain longitudinal and torsional stiffness of the part of the sole under the arch of the wearer's foot. The presence of such a plate can improve the stability of the wearer's foot with respect to the ground surface, and may increase the life of the shoe sole. Theplate10 is also visible inFIGS. 12 to 14.
• FIGS. 3 to 8 illustrate various example arrangements for thecavities2 and inserts5, as mentioned above. InFIG. 3, thecavity2 comprises an opening in theupper surface7 of themidsole3, and is closed at its lower end byoutsole4. InFIG. 4, thecavity2 is shown with an opening above and below.FIGS. 5 to 8 show arrangements in which thecavity2 is closed at its upper end by a minority portion (eg 10%-20%) of the thickness of the material of themidsole3. Theinserts5 may be secured in thecavities2 by any suitable means. If an insert is intended to remain in its cavity permanently, then it may be glued or bonded or welded in place in thecavity2. Theinsert5 may even be supplied as a liquid which can be introduced into thecavity2 and which then sets with a predetermined hardness.FIGS. 5 and 6 show the cavity with and without theinsert5 inserted. The insert of this example comprises abody portion5, which may have a hardness selected to give the desired proprioceptive stimulus pressure to the foot at that location, and anoutsole portion5′, which may comprise a similar material to that of theoutsole4. Alternatively, the insert may be of a single heterogenous piece of material.
• Thelower portion5′ (eg the outsole portion) of theinsert5 may advantageously be wider than the body portion which fits into thecavity2. This has the following advantages which help to maintain a constant proprioceptive stimulus pressure provided by theinsert5 at the location. Firstly, the broaderouter part5′ abuts thelower surface15 of themidsole element3. This prevents the insert from being over-compressed and receding into the cavity. It also distributes the load on the insert more evenly, thereby ensuring a constant proprioceptive stimulus effect from the insert as a whole on the wearer's foot at that location. Secondly, the broaderouter part5′ covers the region where the sidewall of the insert body is in contact with the sidewall of the cavity. If sand, grit, dust or water is allowed to penetrate this region, which may happen in the arrangement ofFIGS. 5 and 6, for example, the accumulated matter may cause a hardening effect which will alter the proprioceptive pressure at the location and/or erode the material of themidsole3 or theinsert5, such that the insert may work loose and drop out.
• FIG. 8 shows an example variant in which theinsert5 extends downward beyond theoutsole4, thereby increasing the proprioceptive pressure effect at the location. This is made possible, with a reduced risk of the insert being pushed up into the cavity, by the shoulder which abuts thelower surface15 of themidsole3 as described above.
• FIGS. 9 to 11 show variants in which anoptional plate16 is included over all or some of theinserts5 in order to delocalise the pressure which occurs between the foot and the individual inserts5. Theplate16 may be hard enough and flexible enough to distribute the pressure without influencing the proprioceptive or sensory-motoric effect of graded or varied hardnesses of the inserts. Theplate16 may optionally cover the whole foot-contact area of the sole or even the whole area of the sole. Theplate16 may optionally be recessed into theupper surface7 of themidsole3 as shown. Theinserts5 ofFIG. 9 are shown flush with the lower surface of theoutsole4. Theinserts5 ofFIG. 10 extend slightly (1 mm to 5 mm) proud of the lower surface of theoutsole4, and theinserts5 ofFIG. 11 are profiled and extend further, thereby further increasing the localised proprioceptive stimulus pressure at the location.
• FIGS. 12 to 14 show variants in which the cavities and inserts are angled slightly from the vertical, in a transverse direction as inFIG. 13 and/or in a longitudinal direction as inFIG. 14. Thevertical axes8,8₁,8₂,8′ of one or more cavities may be angled slightly outwardly or inwardly in order to enhance the effect of the choice of insert hardness. The cavities of the forefoot region may be angled forwards from the vertical in order to increase an acceleration effect at the end of the gait ground contact cycle, thereby enhancing a rolling or rocking in the gait of the wearer. With this configuration it is thus possible to perform a pronation control as discussed above, in addition to enhancing a rolling gait of the wearer. The tilt angles mentioned here are preferably less than 30 degrees, or more preferably less than 15 degrees.
• FIG. 15 shows an example of an insert retention arrangement. The inserts may be retained in themidsole3 by gluing, bonding, welding, or by form-fit, compression fit or other mechanical fitting. Advantageously, the inserts may be glued in position using an adhesive which allows the insert to be released (for example by application of heat) and replaced. Alternatively, or in addition to the gluing, bonding etc, a retention element such as a peg orpin17 may be inserted, for example transversely, as shown inFIG. 15, to secure theinsert5 in position so that it cannot fall out or work its way out of itscavity2.
• Inserts5 may be made so that they can be inserted into themidsole3 by hand, for example.FIGS. 16 to 27 show various configurations in which the lower (outsole)part5′ of the insert extends laterally outward of theinsert body5. Theoutsole4 is provided with an opening shaped and dimensioned to accommodate the correspondinglower part5′ of the insert.
• FIG. 16 shows a simple insert geometry in which thelower part5′ is flush with the upper and lower surfaces of theoutsole4.
• FIG. 17 shows an arrangement in which the upper surface of thelower part5′ is flush with the upper surface of theoutsole4, and the lower surface of thelower part5′ extends proud of the lower surface of theoutsole4. As with any of the arrangements described, the lower surface of thelower part5′ of the insert may be provided with a texture or tread for improved grip.
• FIG. 18 shows an arrangement in which the shoulder formed by the upper surface of thelower part5′ abuts a corresponding shoulder formed in the sidewall of the opening in theoutsole4. In this example, thelower part5′ also extends proud of theoutsole4.
• FIG. 19 shows an arrangement in which thelower part5′ abuts the outer surface of theoutsole4.
• FIG. 20 shows how the side surfaces of thelower part5′ of the insert may have other profile shapes such as the angled surface shown.
• FIG. 21 shows an arrangement in which thelower part5′ of the insert has two shoulders; a first, upper one which may be similar to the abutment arrangement ofFIG. 16 or 17, for example, and a second, lower shoulder similar to the abutment arrangement ofFIG. 19. Two or more shoulders may be advantageous in that they provide more protection against dirt or water ingress. They also provide more surface area for bonding the insertslower part5′ to theoutsole4 and/or themidsole3.
• FIG. 22 shows how the upper part of theinsert body5 may be provided with acavity12 which may help to retain the insert in the cavity by vacuum suction. When vertical pressure is exerted on the insert, compressing it slightly, air may be expelled from thecavity12. When the pressure is release, the surfaces around the cavity may be drawn together by the resulting pressure differential so as to create a gas-tight seal which prevents air from re-entering thecavity12. Thecavity12 may be deeper than illustrated. The hardness of the insert material may be increased so as to maintain the propriocepive (sensory motoric) stimulus effect with the reduced volume of solid insert material.
• FIG. 23 shows a two-shoulder arrangement similar to that ofFIG. 21, in which the lower should is adapted to accommodate bending movement of theoutsole4 by being sufficiently elastic and/or sufficiently well bonded to theoutsole4 that the lower should forms a reliable permanent seal against the ingress of dirt or water.
• FIG. 24 shows how the insert may be shaped to be retained in the cavity by mechanical fitting. In the example shown, the middle part of the insert body may be slightly wider than the opening through which the insert is inserted, thereby preventing the insert from falling out or riding out of the cavity.
• Theinserts5 may be provided with a positive-fit engagements, which may engage with corresponding recesses in the cavity wall, for example. The protrusions may alternatively be arranged in the cavity and the recesses on the insert.FIGS. 24 to 27 show illustrate various further examples of how the inserts may be retained in the cavities by such positive fit or other mechanical interference. Such retention arrangements may be used alone or in combination.
• FIG. 25 shows an example in which the insert is retained in the cavity by one or more latch-rings or laching or stepped protrusions26,27 in the body and/or outsole part of theinsert5.
• FIG. 26 shows an example in which the insert and cavity engage by means of a thread28, whereby the insert can be screwed into the cavity. A slot29 or other engagement profile may be provided for ease of turning the insert.
• FIG. 27 shows how a form fit insert retention may be implemented by angled or tapered surfaces30. In this case it may be advantageous to provide a special tool configured to compress thelower part5′ of the insert during insertion, so that it will pass more easily through opening of theoutsole4.
• The inserts may extend up to 5 mm or more proud of thelower surface15 of theoutsole4, for example, thereby enhancing a sensomotoric (proprioceptive) loading-response of the wearer, in which the foot alters its orientation and movement in response to localised pressure from the inserts and thereby influences the gait of the wearer.
• In the above examples, theinserts5 have been shown inserted from below intocavities2 which extend vertically to a point below theupper surface7 of themidsole3. The inserts and cavities may alternatively be configured to extend right to theupper surface7 of themidsole3 or even to protrude above theupper surface7 so as to create a further enhanced proprioception (sensory-motoric) stimulus in the sole of the wearer's foot.
• Thecavities2 may be provided with aprotective liner18 as shown inFIGS. 28 to 33. Thelinings18 of the cavities may be formed as separate pieces and pressed or bonded into the cavities in themidsole3. Advantageously, thelinings18 may be formed (for example moulded) as part of theoutsole4, for example such that theoutsole4 andlinings18 form a contiguous waterproof barrier to prevent water from contacting the midsole material, which may be partially absorbant. The cavities formed by the linings may be provided with stepped shoulders, as shown inFIGS. 29, 30, 32 and 33, for receiving thebroader outsole part5′ of the insert inserted into the lining.
• The cavities and inserts are shown vertically oriented inFIGS. 28 to 33, however, they may be oriented at up to 15°, or up to 30°, from the vertical, for example to provide priorioceptive stimulus along the direction of local maximum force transfer to the wearer's foot.
• The inserts are shown as straight-sided cylinders, but they may be waisted or bulged so as to enhance their retention in the cavity.
• FIG. 34 shows a variant in which theinsert5 has a substantially round cross-section (eg spherical or cylindrical). Theelastomeric outsole4 and lining18 may be configured to be elastic that the cavity can be opened wide enough to push the round insert in, and tight enough to retain the round insert once inserted.
• FIGS. 35 and 36 show how a retaining lug orprotrusion17 can be formed (advantageously contiguous with the material of theoutsole4 andlining18. The outsole can be made sufficiently elastic that the cavity opening can be widened enough to push in the insert (which may or may not have an indent corresponding to the lug17), such that, when the cavity is allowed to close again, the insert is retained in position by the additional lateral compression of thelug17 on theinsert body5 in thecavity2. Cavities in the forefoot and ball regions may advantageously be provided with one or more such lugs, as these regions are susceptible to the greatest flexing during walking or running. In particular, the lug may advantageously be located on the forwarded side wall of the cavity, so as to retain the insert against flexing from the forefoot region. One or more lugs may optionally be provided on the rearward wall, and/or on one or both lateral or medial side walls of a cavity.
• As shown inFIG. 37, awidened part19 may be formed at a distal end of theinsert5, and may act as a similar retaining function be exerting lateral force on the side walls of thecavity2 into which is it inserted. The distal widenedpart19 may advantageously be made harder than the body of theinsert5, to provide additional ‘bite’ into the side wall. If the insert is made of an elastomeric foam material, the widening may be achieved by pressing a hot plate against the end surface of the insert, or by cutting the insert from an extruded length of the material using a hot wire or blade. This process has the advantage that it also seals the open cellular end surface against eg water absorption.

Claims (20)

1. An article of footwear, comprising:

a sole comprising a midsole part of a first material having a first durometer, the midsole having an upper, foot-facing surface and a lower, ground-facing surface,

an outsole part, below the lower surface of the midsole, the outsole having a second durometer,

a plurality of cavities in a first region of the midsole, each cavity extending along a vertical axis substantially orthogonally to the upper surface, between the lower and the upper surfaces of the midsole, and

a plurality of support adjustment elements, each of which is substantially wholly inserted into one of the vertical cavities so as to adjust a vertical support hardness of the sole at the location of said each vertical cavity;

wherein each vertical cavity comprises an insertion opening in the lower surface for receiving one of the support adjustment elements such that the adjustment element extends through the outsole;

wherein the plurality of support adjustment elements comprises a first support adjustment element having a third durometer and a second support adjustment element having a fourth durometer, different from the third durometer, wherein at least one of the third and fourth durometers is greater than the first durometer; and

wherein each of the adjustment elements comprises a body part for being inserted into the cavity and a lower part, wider than the body part, bonded to or located in an opening of the outsole.

2. The footwear according toclaim 1, wherein the second durometer is greater than the first durometer.

3. The footwear according toclaim 1, wherein the fourth durometer is different from the third durometer, and wherein at least one of the third and fourth durometers is greater than the first durometer.

4. The footwear according toclaim 1, wherein each of the first and second support adjustment elements, when inserted into a first one of the vertical cavities, and the plurality of vertical cavities have substantially the same cross-section as the first vertical cavity in a horizontal plane parallel to the upper and or lower surface, such that the first and second support adjustment elements are interchangeably insertable into the first vertical cavity through the insertion opening of the first vertical cavity.

5. The footwear according toclaim 1, wherein the first support adjustment element, the second support adjustment element and a first one of the plurality of vertical cavities have substantially the same vertical length along the vertical axis.

6. The footwear according toclaim 1, wherein the first and second support adjustment elements and the plurality of vertical cavities each has a substantially constant cross-section along at least a majority of its vertical length.

7. The footwear according toclaim 1, wherein the first and/or second support adjustment elements comprise a sensory-motoric stimulus protrusion configured to extend up to or protrude proud of the upper surface of the midsole, so as to provide a sensory-motoric load-response stimulus to a wearer's foot at the location of the said first or second support adjustment element.

8. The footwear according toclaim 1, wherein the first and/or second support adjustment elements protrude proud of the lower surface of the outsole.

9. The footwear according toclaim 1, wherein a first plurality of vertical cavities is arranged in a first gait control region of the sole, and a second plurality of the vertical cavities is arranged in a second gait control region of the sole.

10. The footwear according toclaim 9, wherein the first and second pluralities of vertical cavities and the plurality of support adjustment elements have substantially the same cross-section, such that the first plurality of support adjustment elements can be fittedly inserted into the vertical cavities of the first and second pluralities.

11. The footwear according toclaim 1, in which the third durometer is at least 5 Shore greater than the first durometer, where the fourth durometer is at least 5 Shore greater than the third durometer and/or in which the third durometer is less than or equal to the first durometer.

12. The footwear according toclaim 1, in which the lower part5′ of the adjustment element extends laterally on average by at least 5% of the width of the body part wider than the opening of the cavity2 into which it is inserted.

13. The footwear according toclaim 12, in which the lower part5′ extends laterally on average at least 2 mm, or at least 4 mm wider than the opening, and/or on average at most 6 mm wider than the body part.

14. The footwear according toclaim 1, wherein the material of the midsole comprises a polyurethane material, and/or wherein the material of the body part of each adjustment element comprises a polyurethane material, and/or wherein the material of the outsole part of each adjustment element comprises a polyurethane material.

15. The footwear according toclaim 1, wherein each adjustment element is provided with a retention element for retaining a body part of the adjustment element in the midsole.

16. The footwear according toclaim 1, wherein the retention element is a pin, insertable transversely through the midsole and the body part.

17. A method of manufacturing a sole for an article of footwear according toclaim 1, the method including:

forming the midsole element by vacuum-moulding the material of the midsole element around formers arranged for forming the cavities with opening to the lower surface of the midsole element.

18. The method according toclaim 17, wherein the material of the midsole element comprises a polyurethane foam.

19. A method of customising the footwear ofclaim 1, so as to control the support provided to a wearer's foot by the sole, the method comprising the steps of:

determining a support requirement of the wearer's foot,

based on the support requirement, selecting said first and second support adjustment elements from said plurality of support adjustment elements,

based on the support requirement, selecting said first vertical cavity, wherein the first vertical cavity is located in a third gait control region for adjusting the support provided by the sole to the wearer's foot for meeting the support requirement, inserting one of the first and second support adjustment elements into said first vertical cavity.

20. The method according toclaim 19, further comprising the step of inserting the other of the first and second support adjustment elements into a second vertical cavity in said third gait control region or in a fourth gait control region, different from the third gait control region.

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