MODULAR INSERT SYSTEM FOR SHOE SOLES
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.
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 INVENTIONIn 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 ARTIt 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 INVENTIONThe 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 to claim 1, a method according to claim 23 and a method according to claim 25. 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.
An example of a support customising system is illustrated in
The example sole 1 illustrated in
The terms lower and upper used in this description are also defined in terms of the vertical axis 8. Note that the term vertical is used in this text to denote a general rather than a precise orientation of the vertical cavities 2, and includes orientations which differ by up to 15 degrees, or alternatively even up to 40 degrees from the vertical axis 8 shown in
While only six cavities/inserts are shown in particular cross-section of
The inserts 5 may also be made of an elastomeric material, for example, and they may have different hardnesses from the midsole 3 and/or from one another. Some of the inserts 5 may have substantially the same hardness as the material of the midsole 3, in order to provide a null support adjustment at a particular cavity 2. It is also possible to provide inserts 5 with lower hardnesses than the midsole 3; this may for example be useful for providing a negative support adjustment in a particular region of the sole 1 by reducing the average hardness of the region by inserting one or more inserts 5 which are softer than the material of the surrounding midsole 3.
The hardnesses of the inserts 5 may be selected from a set of predetermined hardnesses. For example, a pair of shoes having soles such as that illustrated in
When the wearer puts weight on the sole, for example while walking, the inserts 5 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 the inserts 5 each have one of a predetermined set of hardnesses, at least in the vertical direction, and because they extend along substantially the whole vertical depth 11 of the sole 1, or at least substantially the whole depth 11 of the midsole 3, the net vertical hardness of the sole 1 at the location of each cavity 2 is determined exclusively, or in a great majority, by the hardness of the particular insert 5. The hardness of the outsole 4, if it is different from the hardness of the insert 5, may also contribute an effect to the net vertical hardness of the sole 1 at that location, but the contribution may be small, particularly if the outsole 4 is thin and/or the hardness difference between the outsole 4 and the insert 5 is small. Similarly, the contribution of the insole 6 or any minor part of the midsole which extends above or below the insert 5 when the insert 5 is inserted, will also have only a small effect on the net vertical hardness of the sole 1 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 axis 8). 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.
The vertical cavities 2 and the inserts 5 shown in the example of
Because the inserts 5 are oriented substantially vertically in the midsole 3, and because they have relatively small lateral dimensions, multiple inserts 5 and cavities 2 can be located in a particular region of the sole 1 in order to adjust the net vertical hardness of sole with a fine resolution. Thus, a pronation control zone in the forefoot area 12 of the sole 1 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 ten inserts 5 may be the same, or they may be graded. For example, the hardnesses of the inserts may be increased from the rear-most insert 5 to the foremost insert 5.
The discussion above has related primarily to the inserts 5 and cavities 2 of a single shoe. In a pair of shoes, the inserts 5 and cavities 2 may similarly be made so that the same inserts 5 can be used in the cavities 2 of either shoe. The support customising system may be arranged such that, multiple pairs of shoes can share the same set of support adjustment inserts 5.
The use of multiple, interchangeable inserts 5 having different hardnesses means that the support provided by the sole 1 can be finely tuned to the needs of the wearer. The support may be differently tuned between the left shoe and right shoe, between different regions 12, 13, 14 of one sole 1, or even within the same region of the sole 1.
In the example configuration of
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 landing portion 19 of the heel region should preferably be the same for left and right shoes.
Because the inserts 5 of a particular region, or of multiple regions of the sole, may have the same cross-sectional shape, the inserts 5 may be made interchangeable between all cavities 2 of a particular region or between all cavities 2 of the sole. In this case many different configurations of the support offered by the sole can be achieved with a relatively modest number of inserts 5.
Each insert 5 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 in
The multiple cavities 2 may advantageously have the same size and shape, as illustrated in
Medial and lateral control regions 21 and 22 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 the inserts 51 of the medial region 21 and the hardnesses of the inserts 51 and 52 of the medial 21 and lateral 22 control regions, it is possible to influence the degree of pronation of the foot around the stability “S-line” 20. Furthermore, the use of inserts 5 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 inserts 51 illustrated in
The lateral and medial inserts 51 and 52 can further be used to achieve a third-order control effect, in that inserts can be selected to vary the rate of pronation. If the lateral control region 22 is provided with more cavities and inserts 52, (say five inserts in a line running parallel to the heel-toe axis, for example), then the hardnesses of the five lateral inserts 52 can 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 inserts 52 it 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 the inserts 5 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 the interchangeable inserts 52 of the lateral region 22 also apply to the other illustrated regions in
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 the outsoles 4 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 in
Lateral control region 22: 50 Shore, 60 Shore, 60 Shore
Medial control region 21: all 50 Shore or less
Forefoot lateral control region 23: all 60 Shore
Example 2: For Correcting a Delayed OverpronationLateral control region 22: all 50 Shore (no correction)
Medial control region 21: 50, 60, 70, 80, 80, 60 Shore
Forefoot lateral control region 23: all 60 Shore
Example 3: For Correcting Severe General OverpronationLateral control region 22: 50, 50, 60 Shore
Medial control region 21: 70, 80, 90, 80, 70, 60 Shore
Forefoot lateral control region 23: all 60 Shore
Example 4: For Correcting Early, Slight OverpronationLateral control region 22: 50, 50, 60 Shore
Medial control region 21: 70, 60, 50, 50, 50, 50 Shore
Forefoot lateral control region 23: 70, 60, 50, 50, 50 Shore
Example 5: For Correcting Delayed, Slight OverpronationLateral control region 22: all 50 Shore (no correction)
Medial control region 21: 50, 50, 60, 60, 70, 70 Shore
Forefoot lateral control region 23: all 50 Shore (no correction)
The sole of
The lower portion 5′ (eg the outsole portion) of the insert 5 may advantageously be wider than the body portion which fits into the cavity 2. This has the following advantages which help to maintain a constant proprioceptive stimulus pressure provided by the insert 5 at the location. Firstly, the broader outer part 5′ abuts the lower surface 15 of the midsole element 3. 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 broader outer part 5′ 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 of
Inserts 5 may be made so that they can be inserted into the midsole 3 by hand, for example.
The inserts 5 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.
The inserts may extend up to 5 mm or more proud of the lower surface 15 of the outsole 4, 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, the inserts 5 have been shown inserted from below into cavities 2 which extend vertically to a point below the upper surface 7 of the midsole 3. The inserts and cavities may alternatively be configured to extend right to the upper surface 7 of the midsole 3 or even to protrude above the upper surface 7 so as to create a further enhanced proprioception (sensory-motoric) stimulus in the sole of the wearer's foot.
The cavities 2 may be provided with a protective liner 18 as shown in
The cavities and inserts are shown vertically oriented in
The inserts are shown as straight-sided cylinders, but they may be waisted or bulged so as to enhance their retention in the cavity.
As shown in
Claims
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 to claim 1, wherein the second durometer is greater than the first durometer.
3. The footwear according to claim 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 1, wherein the first and/or second support adjustment elements protrude proud of the lower surface of the outsole.
9. The footwear according to claim 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 to claim 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 to claim 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 to claim 1, in which the lower part 5′ 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 cavity 2 into which it is inserted.
13. The footwear according to claim 12, in which the lower part 5′ 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 to claim 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 to claim 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 to claim 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 to claim 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 to claim 17, wherein the material of the midsole element comprises a polyurethane foam.
19. A method of customising the footwear of claim 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 to claim 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.
Type: Application
Filed: Sep 20, 2019
Publication Date: Jun 24, 2021
Inventors: Harald BECK (Zürich), Tobias SCHUMACHER (Langenthal)
Application Number: 17/273,236