FR2646062A1 - DEVICE FOR STABILIZING, DAMPING AND RESETTING ENERGY FOR FOOTWEAR, ESPECIALLY SPORTS AND SHOES EQUIPPED WITH SUCH A DEVICE - Google Patents

Abstract

Shoe characterized in that it comprises, housed in the sole, directly above the heel, an elastic stabilization element 40 having a higher local stiffness on the outer side 45 of the foot than on the inner side 44 of the foot. Application to sports shoes.

Description

The present invention relates to a stabilizing device for

  shoes, likely to improve

  capacity for depreciation and restitution of these

  Nières. It also relates to a shoe, especially sports, equipped with such a device. Although not limited to such sports shoes, the present invention is concerned, with regard to footwear intended for running, with the solution of the following general technical problems: - increase of the intrinsic stability of

  soles of shoes, with the conse-

  trauma due to the instability of the soles of the prior art; - Increasing the damping capacity of the sole, and more particularly the heel, while minimizing the decrease of this capacity due to aging and prolonged use; - Increased energy recovery capacity of the soles, especially the heel of the latter, at each step of the race; - in general, increase in

comfort of the shoes.

  To fully understand the present invention and its interest, one must first understand: - the concept of depreciation, and the interest in maintaining as long as possible the capabilities

  original damping of a sole and, more specifically,

  his heel; - the distribution of pressure and support on the arches of the foot during each step during the race; - the notion of stability and the adverse effects of instability; - and the form in which the energy, linked to the impact of the foot on the ground during each step, can be usefully restored to allow an improvement of

runner performance.

  The cushioning capacity of a sole or heel of a sole of a shoe, in particular a sport boot, may

  defined as the progressive absorption power

  S sive vibrations or shockwaves crossing the sole, and the body of the runner, during each impact on the ground of the

foot during the race.

  It is understandable that a low depreciation capacity

  is likely to generate long runners, joint trauma, tendon and even muscle. It is therefore of interest that a shoe initially has a high damping capacity and can maintain it for as long as possible despite the use of the shoe and thus this ability

  does not decrease with time decreases little.

  FIG. 1 illustrates in particular schematically the distribution of the pressures and supports on the sole of the shoe and on the arches when

each step during the race.

  In 10 it is schematized the silhouette in plan of a left shoe. In 30 it is schematized in fine lines interrupted the silhouette of the foot inside the shoe; in 31 that of the front of the heel of the foot; in 32 that of the plantar arch; in 15a - 15th that of the five

  metatarsals and in 33a - 33rd that of the five phalanges.

  Classically, it is considered that at the level of the foot, a running step takes place in a succession of three phases: - a phase of impact of the foot with the ground; - a phase of "unfolding" of the foot;

- a propulsion phase.

  Moreover, two categories of riders must be distinguished: riders known as "supinators" and so-called "pronators". For the two categories of riders, and for the vast majority of these (more than 99%), the impact takes place in an area of the heel of the shoe referenced in

  11 and located on the outer rear portion thereof.

  As a general rule, it is considered that a Kg rider exerts against the ground, and therefore the heel of his shoe, at each impact a force of 2000 N. After the impact, in the unwinding phase,

  the pressures will move towards the front of the foot.

  In the case of supine riders, the pressure transfer zone is essentially located on the outer half of the foot, since during the unwinding phase the pressures generally move along a line 12 in the shape of an arch oriented towards the outside and towards the outside. the front of the foot. The unwinding line 12 shown in FIG. 1 represents the displacement of the pressures for a supinator rider described here as "normal", that is to say a rider whose foot is neither excessively flat nor excessively hollow. In the case of a flat foot, the line 12 moves inwardly of the foot, while in the case of a relatively hollow foot, the line 12 moves to the outside of the foot. It is observed that the line 12 develops globally from the baricenter 13 of the impact zone 11, follows an arch corresponding to the development of the foot and ends at 14 to

  level of the first (15a) and second (15b) metatarsals.

  During the propulsion phase, the rider leans on his five metatarsals' (15a - 15e) to exert the trigger which propels him into the next step. It is known that the supports are not uniformly distributed over the five metatarsals. It is enough to remember here that in general, but this one is not absolute, the more the runner goes fast and wishes, consequently, to exercise a significant force of propulsion, the more the global support moves

to the first metatarsal.

  In runners qualified as pronators, during the unwinding phase, the pressure shifts are generally along a double arch line 161 and 162. Indeed, from the impact zone 11, and more precisely from the baricentre 13 of this area of impact, the pressures move firstly according to a first arch 161 to reach an area 17 located on the inner back of the foot. From the baricenter 18 of this zone, the pressure moves along an arch 162 which more or less tangentially joins the line 12 of displacement of the supinator foot pressure, substantially backward.

the fourth metatarsal 15d.

  The relaxation phase of the pronator runners is

  much the same as that of the supinators.

  The above information is well known to those skilled in the art who know that they relate to pronator and supinator runners corresponding to an average observed over a relatively large population. he

  Of course, there are many very special cases.

  A shoe is said to be stable when, while allowing the absorption of the vibrations or shock waves during the impact on the ground on the zone 11 and the various supports ensue (as explained above), it does not allow not excessive deformation and / or crushing of the various areas of impact or support which would result in deformation of the structure and consequently a spill of the foot to the outside or towards

inside.

  In Figure 2, there is illustrated, in section at the heel, a stable shoe during the impact on the ground. The area of impact is schematized as 11. In Figure 3, there is shown an unstable shoe of similar shape. It can be seen that the crushing at the heel 20 is greater, which causes a deformation of the external buttress 21 of the shoe,

  resulting in a spill of the foot towards the ex-

  in the direction of the arrow A. This phenomenon is identical when the shoe has instability on its internal side, especially at the zone 17. Such a spill of the foot, inward or outward according to the case (pronator or supinator), during each step of the race, leads in the long term to articular, tendonous and muscular traumatisms. We understand

  the interest of developing stable shoes.

  To allow the increase of the runner's performance, the restitution of the energy related to the impact of the foot during each running step must generally take the form of an increase in speed. foot unwinding during the unwinding phase between that of impact and that of propulsion. As a result of this increase in speed, there is amplification of the relaxation force at the level of the metatarsals which results in an increase in the speed of the runner, the latter being of the supinator type

or pronator.

  For the pronator runners in particular, the increase in the speed of the unwinding phase, as a result of the restitution of the energy of the impact, is also reflected in a reduction of the support time on the internal rear end. foot (zone 17). As a result, there is a decrease in the duration during which the zone 17 is solicited at each step and thus increases the longevity of the damping capacity of this zone. The restitution of the energy related to the impact has, therefore, for the pronator runners, the double effect of reducing the trauma possibly associated with the support on the zone 17 at the back of the foot and reducing the aging of the

  damping capacity of the sole at this level.

  With the aim of increasing comfort, reducing the trauma associated with running and increasing the performance of runners, the inventor has been keen to develop a shoe and means intended to be integrated into this shoe. allowing: - to increase the intrinsic stability; - increase the depreciation capacity and especially the longevity of this depreciation capacity;

  - and to increase the capacity to restore

  energy in the useful form set out above.

  There are, in the state of the art, various sports shoes with means to improve the damping capacity or the return of energy.

  Thus, under the trademark "NIKE" it is commercial.

  a shoe whose heel is made of polyurethane. Inside the heel is molded a

  hollow housing enclosing an "air cushion".

  The "air cushion" increases the cushioning capacity of the shoe, particularly with respect to shoes whose heel is simply made of polyurethane or materials such as those known under the trademark "E.V.A.". However, this device does not give the shoe a quality of stability in the sense defined above. Moreover, the ability of the device to render useful energy related to the impact is

  very small, not to say non-existent.

  Under the brand name "REEBOK" is marketed a sports shoe in which is cleaned in the sole four hollow tubes arranged in transverse direction and arranged in general, directly above the heel (and sometimes to

the plumb with the metatarsals).

  This device gives the shoe a fair

  good damping capacity and a capacity to restore

  higher energy than the air cushion model.

  However, the stability of such a shoe is low.

  Under the trademark "ASICS-TIGER" it is

  a shoe comprising a silicone-based gel disposed in housings provided in the soleplate.

  the heel and metatarsals.

  This shoe has a good cushioning capacity. On the other hand, its qualities of stability and

  of energy restitution are quite weak.

  From the foregoing it appears that, to the knowledge of the inventor, there are no running shoes with good stability. A fortiori, in the state of the art, there are no shoes with good stability and good stability.

  capacity of damping and restitution of energy.

  The present invention aims at a shoe

  presenting at least these three qualities.

  In general, a shoe according to one aspect of the invention is characterized in that its sole, directly above the heel of the foot, has a higher stiffness on the external side of the foot than on the inner side.

of the foot.

  According to another aspect of the invention, and according to a preferred embodiment thereof, the shoe comprises, housed in the sole, above the heel, an elastic stabilizing element having a higher stiffness on the side. external of the foot than the side

internal foot.

  In this preferred embodiment, the stabilizing element according to the invention is characterized in that it is elastic and that it is in the form of a hollow cylindrical volume of constant thickness whose guiding curve is such that -. that the cross-section of the element has, at the level of the element intended to be in line with the internal side of the foot, a height greater than that of the section of the directional curve of the element, at the level of this element. last intended to be in line with

the outside of the foot.

  Advantageously, in this embodiment, the steering curve extends globally. transversely to a longitudinal axis of the foot, while the generators

  extend parallel to this axis.

  Thanks to these provisions the shoe according to the invention has a stability greater than that held in the prior art, in particular that whose

  structure was succinctly recalled above.

  Indeed, by giving this element a stiffness on its side disposed vertically above the outer side of the upper foot to the stiffness of the element in line with the inner side of the foot, it limits the deformation of the heel on the outer side foot during the impact, compared to the internal side. In this way, it increases the intrinsic stability of the shoe avoiding excessive deformation with the consequences explained above to

the support of Figures 2 and 3.

  Likewise, the higher stiffness on the external side of the stabilizing device contributes to increasing, for the external side, its shock absorbing capacity related to the impact. In addition, since the stabilizing element is elastic, part of the energy related to the impact is restored in a very short period of time, so that, overall, compared to the shoes of the prior art, equipped with such a stabilizing element, the damping capacity of the shoe is solicited, at each step, for a shorter period of time. This not only results in better impact damping, but also increases the cushioning life of the shoe. It also results in a wear of identical damping qualities on the internal rear and on the external rear of the boot, which is favorable in terms of stability because it prevents a spill of the structure of the shoe. on the outside as is currently the case in the

running shoes.

  The implementation of the invention by the element

  cylindrical structure whose structure is briefly described below.

  above is particularly simple and advantageous. Indeed the stabilizing element is in the form of a cylindrical volume of somewhat unusual shape since the

  its characteristic curve and which, advantageously,

  in a preferred embodiment is closed, has, in section, a substantially lower height on the inner side than on the outer side. Since the cylindrical element is made in this epoxy resin / fiberglass fabric embodiment, of substantially constant thickness, it follows that an element whose stiffness is more important on the external side than on the side is easily obtained. internally, with the advantages mentioned above. For pronator feet the element of

  stabilization thus designed has the added advantage

  it occupies, in the heel of the shoe, a substantially larger volume on the inner side than on the outer side. Thus during the tilting of the heel of the foot inward (line 161 leading to the area 17) as the tilting inwards, the following phenomena occur: - on the one hand, the thickness of material between the runner's heel and the stabilizing element being weaker on the inner side than on the outer side of the foot, this material is more quickly squeezed and the heel, in its tilting, encounters a resistance;

  - on the other hand, this resistance increases as

  and-to-measure the deformation of the cylindrical element on

its internal side.

  Once the stabilizing element is deformed on the inner side, it resumes its initial shape in a shorter period of time than in the shoes of the art

  previous o the heel is only made of polyurethane

  réthane. Thus the part of the heel of the shoe -in line with the inner rear part of the foot is solicited for a shorter period of time in each step, which increases the long life of the shoe. damping of this part of the boot compared to that of the prior art, while avoiding an inward sagging of the shoe structure, which is favorable in terms of stability

of it.

  According to another characteristic of the invention the stabilizing element extends longitudinally substantially under the entire heel. In the mode of

  preferred embodiment the cylindrical element extends

  gitudinally globally under the entire heel of the runner. Preferably the stabilizing element has a substantially uniform stiffness in the longitudinal direction. Thanks to these provisions during the impact, the stabilizing element deforms significantly more on the back than on the front. As the stabilizing element is elastic out of its recovery of the original shape the rear portion of the stabilizing element renders a substantially greater energy than the front part of this element. It follows that the runner's heel is significantly more stressed on its rear than on its

  before and therefore tends to "swing" forward.

  In practice, such a return of energy results in an accelerated unfolding of the unwinding phase, which

  is consistent with the purpose assigned by the inventor.

  The features and benefits of

  present invention will emerge from the description which will

  follow with reference to the accompanying drawings in which: - Figure 1, partially already described, also illustrates in plan view the implementation of a stabilization device according to the invention; Figures 2 and 3 have already been described; - Figure 4 is a sectional view along the line IV-IV of Figure 1; FIG. 5 is a perspective view of the stabilization device illustrated in section in FIG. 4;

  FIG. 6 is a longitudinal sectional view

  partial dinal along the line VI-VI of Figure 1;

  FIGS. 7a-7d are corresponding views.

  FIG. 4 illustrates, in cross-section, the deformation of the stabilization device in various situations; FIG. 8 is a sectional view corresponding to FIG. 4 and illustrates the heel of the boot after prolonged and intensive use thereof, and FIG. 9 illustrates in a rear view the heel of a boot of the shoe. prior art used so

  intensive by a pronator type runner.

  According to the embodiment chosen and shown in the figures, a shoe according to the invention has a plan shape identical to that already described in FIG. 1. The elements described in support of FIG. 1 (the arrangement of the main elements of the foot and the distribution of pressures) remain obviously valid with respect to the shoe according to the invention. In this figure it is illustrated, under the reference 40, the position of a stabilization device that we are going

  now describe in support of Figure 5.

  The stabilization element illustrated in FIG. 5 is in the form of a cylindrical volume whose reference curve bears the reference 41 in FIG. 5. It can be seen that this guide curve is such that its cross section (axis 42) in the vicinity from its end. right, has a length substantially greater than its cross section near its left end in Figure 5 (axis 43) .- Within the meaning of the present invention we say that the cross section 42 is higher than the cross section 43 In the embodiment shown, the guide curve 41 is in fact formed of two quasi-semicircles (44 on the left, 45 on the right) whose ends

  are joined by two straight lines 46, 47 defined

  respectively upper and lower faces bearing the same references. Straight sections 42, 43

2646062,

  12- correspond substantially (to drawing errors) to the diameter of the half-circles 44 and 45. The generators are

  oriented perpendicular to the guide curve 41.

  In the embodiment currently described, the axes 42, 43 are 44 mm apart, the small half

  circle 44 having a radius of 6 mm while the large half

  circle 45 has a radius of 10 mm. The cylinder 40 extends over

a length of 40 mm.

  It is here made of epoxy resin / fabrics.

  fiberglass, and is in the form of an annular body whose wall thickness; constant on any

  the periphery of section 41 is one millimeter.

  Such a stabilizing element has an overall stiffness of 1854 kg / mm, in one direction

parallel to an axis 60 (Figure 4).

  According to one characteristic of this embodiment of the invention the stiffness is distributed locally as follows: If we consider that the local stiffness at the axis 60 in a direction parallel to this axis, is equal to a factor of 100, the local stiffness at the axis 43 of FIG. 5 along a direction parallel to this axis is equal to a factor of 200 and that at the level

  of the axis 42 of Figure 5, is equal to a factor of 150.

  This distribution of stiffness is illustrated in FIG.

by the arrows 200, 100 and 150.

  In FIGS. 1 and 4 is illustrated the position of the stabilizing element 40 in the heel 20 of the

  shoe illustrated. It is observed that the stabilizing element

  tion is such that these generatrices are parallel to the longitudinal axis 50 of the foot (Figure 1). The guide curve is therefore transverse to this axis. Generators from the large semi-circle 44 are arranged substantially parallel to the right internal edge of the shoe while those from the small diameter semi-circle 45 are disposed substantially parallel to the left outer edge of the shoe generally to

the heel of the runner.

  It is furthermore observed that the upper face 46 of the stabilizing element 40 is arranged in such a way that it is horizontal to a few millimeters under

the heel of the runner.

  In 21 schematically illustrated a buttress of the shoe. This buttress is of conventional structure and does not have to be described in detail here. Similarly, the heel 20, apart from a hollow housing of complementary shape to the stabilizing element 40, is for the rest of conventional structure. It is here realized in a

molded polyurethane block.

  FIG. 7a illustrates the deformation of the heel of the boot and in particular of the stabilizing element during the impact phase. In this figure, the impact zone is recognized. It is observed that at this zone there is a deformation of the structure

22 polyurethane heel 20.

  The deformation of the stabilizing element 40 is illustrated in solid lines while in fine mixed lines the original shape of the stabilizing element has been illustrated. It is observed that the stabilizing element is a little deformed on the left (outer side of the foot) while the deformation on the inner side of the foot (large

diameter 42) is almost zero.

  In any case, the heel 20 is deformed

  overall less in a shoe equipped with a

  positive stabilization according to the invention (Figure 7a) that in a shoe does not include such a device (Figure 3). This characteristic is favorable in terms of stability because indeed the structure 21 of the buttress of the shoe takes a slight angle on the left much lower than it would take if the deformation was

  similar to that of the heel shown in Figure 3.

  At the beginning of the run-up phase, in supinator-type runners, there is a phase of

  recentration where the pressure is distributed in a transverse

  sal, evenly over the entire heel.

  It is observed that at the axes 43 and 42 the stabilization device is not visibly deformed; in fact, the stabilizing device is slightly deformed in an identical manner at each of the axes 42, 43. On the other hand, the central part of the

  stabilizing device is very deformed.

  In the pronator type of runners there is tilting of the heel inwards as explained above in support of Figure 1. In Figure 7c is illustrated the deformation of the heel of the shoe in this case. It is observed that at the axis 42 there is a large deformation due to the support of the runner on the zone 17 (Figure 1) as well as on the central part, especially to the right of the axis 60. In contrast at axis 43 the

deformation is zero.

  In the case of FIG. 7b as well as that of FIG. 7c, the substantial deformations of the elastic stabilizing element will cause a

restitution {'energy.

  We realize the interest of a lower local stiffness at the axis 42: such a

  stiffness allows deformation of the stabilizing element

  more progressive, and more important, this distortion

  being less traumatic for the runner; Moreover, a lower stiffness at the axis 42 is justified by the fact that the pressures are less important on the inner side of the foot than on its outer side, as well for a rider pronator as for a rider supinator, for a pronator runner pressure on the inner side of the foot being otherwise

more prolonged.

  It can thus be seen that both during the impact phase and at the start of the unwinding phase, the same stabilization device can be used with pronator and supinator runners with advantages in

both cases.

  FIG. 7d shows the heel of the boot and the stabilizing element at the end of the unwinding phase, at the beginning of the relaxation phase for a

  pronator runner. It is observed that the stabilizing element

  has returned to its original form and has restored

some energy.

  Figure 6 shows a long section

  of the stabilizing element 40, along the line VI-VI of FIG. 1, during the impact phase (the line

  VI-VI cutting is also illustrated in Figure 7a).

  It is observed that under the impact the face

  upper 46 of the stabilizing element was deformed.

  As the impact is located substantially more on the back of the shoe, the stabilizing element 40 deforms more towards the rear 52 of the cedernier than towards the front portion 53, so that the upper face 46 of the element 40 takes an angle with respect to the horizontal referenced in

in Figure 6.

  Concomitantly with the end of the impact phase, the element 40 tends to return towards the rest position illustrated at 46 'in FIG. 6. Returning to this rest position, the element 40 thus exerts a

  force exerted in fact in an arc (arrow F).

  Force F actually has the effect of accelerating

  the stage of unfolding of the foot explained above.

  In general, it will be observed that the stabilizing element 40 described in support of the figures

  is in fact a special case of a stabilizing element

  elastic structure having a substantially higher stiffness on its side intended to be at the foot of the external part of the foot than its side intended to be plumbed

of the inner part of the foot.

  Similarly, since the stiffness of the stabilizing element remains substantially constant along a longitudinal axis of the latter, the impact causes the stabilizing element to deform more on its rear than on its front so that the force exerted by the rear of the latter is higher than the force exerted by the

  parts of the stabilizing element disposed on the front.

  This generally translates into a push towards

  the front accelerating the phase of unwinding of the foot.

  It emerges from these explanations that the stabilization element described in support of the figures is only one embodiment among others and that it can in particular be replaced by any element having a distribution.

equivalent stiffness.

  In Figure 8 there is illustrated the stabilizing element 9 after intensive use (running for about a thousand kilometers). It is observed that the material constituting the heel 20 disposed between the face

  upper section 46 of the stabilizing element and the

  the shoe has substantially compressed but that overall the heel 20 has, in cross section,

  a geometry similar to that illustrated in Figure 4.

  In FIG. 9, by way of comparison, the geometry of the heel 20 of a sports shoe not equipped with such a stabilizing element and used for approximately a thousand kilometers of running by a runner of the same type is illustrated. pronator. There is a clear sagging towards the inside of the foot (to the right in the figure) and a deformation of the right buttress 21d

of the structure.

  On the other hand, there is a certain deformation of the left buttress 21g due, even in a pronator runner, to the impact phase. The deformations of the right and left buttresses are due, among other things, to

lack of stability.

  Under reference 65 is shown in phantom the original shape of the heel and buttresses before subsidence. It is observed that the shoe illustrated in FIG. 8 is more satisfactory in many respects and that,

  In particular, we do not witness the deformations of

  strong. Of course, the present invention is not limited to

  in no way to the embodiment described and shown.

  It has been explained above that the stabilizing element 40 could be replaced by any element having a distribution of stiffness similar to those

  described in this application.

  Moreover, the present application is not limited to running shoes. It will be apparent to those skilled in the art that it can advantageously be implemented in any sports shoe in which it is necessary to run. In addition, it will be apparent that the elastic stabilizing element with a high energy recovery capacity such as that according to the present invention can advantageously be used in

  footwear for sports such as volleyball

  ball or basketball. In fact, in certain circumstances

  steadiness, the return of energy is linked to an impact

  on the heel, can be useful to increase the performance

  maneuvers of the basketball or volleyball player

vertical jumps.

  Finally, it will be observed that the present invention can also advantageously be applied to walking shoes. Indeed, if in such shoes the phenomena described in support of Figure 1 are not so marked, they do not exist and the trauma associated with it, if they do not appear at the end of a time comparable to what was observed for the runners, appear nonetheless after several years. It is therefore particularly advantageous to provide simple walking or city walking shoes with

  stabilization according to the present invention.

Claims (8)

  1. Shoe characterized in that its sole, above the heel of the foot, has a stiffness more   high on the outer side of the foot than on the inner side of the foot.   2. Shoe characterized in that it comprises, housed in the sole, above the heel, an elastic stabilizing element (40) having a higher local stiffness on the outer side (45) of the foot than on the inner side (44) of the foot.   3. Shoe according to any one of   claims 1, 2, characterized in that the ratio   between the external and internal local stiffness of the element   stabilization is of the order of 1.3.   4. Shoe according to claim 2 or claim 3, characterized in that the stabilizing element extends longitudinally substantially under the entire heel.   Shoe according to claim 4, characterized in that the stabilizing element has a substantially uniform distribution of local stiffness. in longitudinal direction.   6. Shoe characterized in that it comprises, housed in the sole, above the heel, an elastic stabilizing element (40) in the form of a hollow cylindrical volume whose guide curve is such that the cross section of the element   has a height (42) on the inner side of the upper foot   than * (43) on the outer side.   7. Shoe according to claim 6, characterized in that the guide curve extends generally transversely to a longitudinal axis (50) of the foot, while the generatrices extend in parallel to this axis.   8. Stabilization device for shoe, intended to be housed in the sole thereof, directly above the heel, in the form of a hollow cylindrical elastic volume of constant thickness (40) whose guide curve is such that the cross-section of the element has, at the level of the element intended to be in line with the internal side of the foot, a height (42) greater than that (43) of the section of the guide curve of the element, at the level of the latter intended to be in line with the outside of the foot.