WO1999038406A1

WO1999038406A1 - Radiused forefoot sole edge and a method for manufacturing a radiused forefoot sole edge

Info

Publication number: WO1999038406A1
Application number: PCT/US1999/001475
Authority: WO
Inventors: Roland Seydel
Original assignee: Fila Sport S.P.A.
Priority date: 1998-01-30
Filing date: 1999-01-29
Publication date: 1999-08-05
Also published as: AU2561599A

Abstract

A sole (10) for an article of footware and a method of manufacturing such a sole includes steps such that the sole includes a substantially planar outer surface (18), a side wall (26) provided on the periphery of the outer surface and a curved medial forefoot portion (14). The sole is particularly well suited for motions and movements performed on a court surface such as during racquetball, tennis and basketball, for example. Preferably, the curvature of the medial forefoot portion is tangential with the outer surface of the sole and the radius of curvature gradually increases from the area of the medial forefoot adjacent the arch towards the front end portion of the sole.

Description

Radiused Forefoot Sole Edge and a Method for Manufacturing a Radiused Forefoot

Sole Edge

This application is based on U.S. provisional application Serial No.60/073,206 filed January 30, 1998, the priority of which is hereby claimed.

BACKGROUND OF THE INVENTION Field of the Invention:

The present invention is directed to a sole of an article of footware, and in particular a sole of an article of footware that includes a rounded forefoot medial sole edge.

Discussion of the Background

Sport shoes, such as tennis shoes or other court shoes have long been known. However, known sport shoes have not heretofore provided sufficient support and traction for court sports such as tennis, racquetball, or basketball, for example. In particular, known sport shoes have failed to provide adequate traction during sharp cutting or turning movements of a user during a court sport such as basketball or racquetball. It is during these types of motions, i.e., sharp cutting or turning, that many injuries have been experienced. For example, when a racquetball player is poised on their toes in anticipation of movement from side to side, the area of contact between the user's shoe and the court surface is concentrated beneath the forefoot area of the sole. When a user lunges to one side, for example, when a user lunges to the left from such a stance, the right foot is generally rolled inward, thereby concentrating the area of contact to the medial edge of the forefoot area. Since conventional and long used court shoes have a substantially planar sole surface with a sharp edge along the periphery of the sole, as a user tilts their foot inwardly or medially in an effort to push off, the area of contact between the user's shoe and the court surface shrinks almost instantaneously, thereby rapidly reducing traction.

For example, if a racquet ball player is standing slightly crouched with their knees bent and with feet spread approximately as wide as their shoulders, which is a typical stance taken during racquetball, and the user pushes off with their right foot to move their body in a leftward direction, the user tends to roll the right foot to the left so as to put the majority of their body weight onto the big toe of their right foot. However, as mentioned above, conventional court shoes typically have a substantially planar bottom with a sharp transition to a vertical wall along the periphery of the sole. Therefore, as the user rotates their foot during the push off, the area of contact between the sole of the user's shoe and the court moves to the outer peripheral edge of the shoe in the medial forefoot area. Since the transition between the substantially planar bottom of the shoe and the peripheral wall was typically sharp, the area of contact shrinks to a minuscule size thereby raising the risk that the user will lose all traction and fall or trip. Furthermore, since the area of contact shrinks to such a small size, a relatively minuscule amount of liquid such as water or sweat could cause the user to fall.

In order to overcome the drawback of having a sharp edge at the medial portion of the forefoot area, it is known to provide the medial forefoot area with a curved edge between the outer peripheral wall and the bottom wall of the sole. For example, U.S. Patent 4,559,723, issued to Hamy et al. teaches providing a curved edge region to the outsole on the medial side of the shoe, extending up over the side of the sole to provide enhanced gripping in lateral lunge movements. However, it has been found that a merely curved or tapered medial forefoot area does not provide ideal traction during sharp cutting motions or lateral lunges performed on court surfaces.

In particular, it has been found that when the transition between the substantially planar lower surface of the outsole, is not tangent to the beginning of the curved portion of the outsole, the rolling motion of a user's foot during a lateral lunge is inhibited if their is a non-continuous or non-tangential junction between the curved portion and the planar lower portion of the shoe. Such a discontinuous junction has been found to cause a non-continuous rolling motion during the lateral lunge, that can result in a loss of balance or injury. For example, if the curved portion is not tangential with the planar outer surface of the outsole, the area of contact between the sole and a court surface rapidly shrinks as the sole is rotated towards the direction of the lunge because of the non continuous curvature of the transition between the curved portion and the planar bottom surface of the outsole.

Additionally, it has been found that because the portion of the medial side of the

-2- outsole nearest the forward end of the shoe curves and narrows, the area of contact between the sole of the shoe and a court surface inherently is smaller when a user performs a lunge that includes both lateral and forward components. For example, if a user lunges partially forward and partially to their left, the user will tend to roll their right foot towards the medial side and forward, thereby placing the forward most portion of the medial side of the shoe sole in contact with the court surface. As the degree of movement becomes directed in a more forward direction, the area of contact between the sole of the shoe and the court surface becomes smaller since the width of the sole across the front end thereof is much narrower than the entire medial side of the sole. Therefore, when a user makes a partially forward and partially lateral lunge to the left, which brings a smaller area of contact between the sole of the shoe and the court surface, traction rapidly declines as the user rolls their foot through the lunging motion, as compared to the traction achieved during a purely lateral lunge.

SUMMARY OF THE INVENTION

Accordingly, it is one object of the present invention to provide for increased comfort and stability for a user of an article of footware when the user performs lateral lunging movements.

It is another object of the invention to provide increased traction and increased area of contact between the sole of a user's shoe and a court surface when the user performs various lateral lunging motions.

It is yet another object of the invention to provide more consistently sized areas of contact between the sole of a user's shoe and a court surface when the user performs various lateral lunging motions which include forward components.

According to one aspect of the present invention, a shoe sole is provided with a substantially planar outer surface, a side wall arranged around the periphery of the substantially planar outer surface, and a medial forefoot portion that is curved and substantially tangential to the substantially planar outer surface and in contact with the side wall. By providing the medial forefoot portion with a curvature that is substantially tangential to the substantially planar outer surface, the present invention enables a user to smoothly roll their foot in a direction towards their instep, or the medial portion of their foot, such as those motions typically performed during lateral lunging-type motions commonly performed during court sport activities. In particular, by forming the medial forefoot portion tangentially with the substantially planar outer surface, the area of contact smoothly transitions from the main portion of the substantially planar outer surface to the medial forefoot portion without encountering bulges or unstable positions so that a user can smoothly perform a lateral lunge without the danger of a sudden loss of balance or twist which could cause a loss of balance or an injury.

According to a second aspect of the invention, a shoe sole is provided with a medial forefoot portion that includes a first radius of curvature proximate to the arch portion of the sole that is smaller than a second radius of curvature of the medial forefoot portion near the forward end of the sole. By providing the medial forefoot portion with such an increasing radius of curvature, the present invention compensates for the smaller area of contact that is inherently formed when a user rolls their foot towards the forward end of the sole as compared to when a user rolls their foot in a pure lateral direction. By providing a larger radius of curvature at the forward end of the sole, the present invention provides a larger area of contact than would otherwise be achieved if the same radius of curvature was used along the entire length of the medial forefoot portion. Thus, traction available to the user is more consistent over the range of lateral lunging motions from purely lateral lunges to lunges directed substantially forward.

Preferably, the medial forefoot portion is provided with a plurality of rectilinear channels, i.e., channels with a substantially rectangular cross section, substantially parallel to the longitudinal axis of the sole. Provided as such, the transition or junction between the substantially planar outer surface and the curved part of the medial forefoot portion is smooth and is provided with some flexibility when a substantial part of the user's weight is transferred to the medial curved part of the medial forefoot portion.

BRIEF DESCRIPTION OF THE DRAWINGS Aside from the provisions described above, the invention also consists of a certain number of other provisions which will be explained below with reference to the non-limiting illustrative embodiments described with reference to the accompanying figures, of which:

-4- Figure 1 is a bottom plan view of the outer surface of a sole of an article of footware according to the present invention;

Figure 2 is a cross-sectional view 2-2 shown in Figure 1 ;

Figure 3 is a front right top perspective view of a shoe including the sole according to the present invention;

Figure 4 is a side elevational view of a shoe having the sole according to the present invention;

Figure 5 is a bottom plan view of a shoe sole incorporating the present invention;

Figure 6 is a side elevational view of a shoe incorporating the sole of the present invention;

Figure 7 is a front elevational view of a shoe with a sole according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to Figure 1, a shoe sole 10 is shown in bottom plan view and includes generally a front end 12, a medial forefoot portion 14, and an arch portion 16. The outer surface 18 is shown in plan view in Figure 1 and includes a tread pattern 20 which may be constructed in any known manner, such as molding and molding and cutting or scoring. Outsole 22, upon which outer surface 18 is formed, may be constructed of any known material, including natural or synthetic rubbers, for example. Furthermore, portions of the outer surface 18 may include exposed portions of blown EVA, which is commonly used in making portions such as midsole 24, and well known in the art.

As shown in all of the figures, the medial forefoot portion 14 of the sole 10 is curved between the outer surface 18 and the side wall 26. As shown in the figures, side wall 26 is generally formed around the periphery of outer surface 18, and may be formed of any one of the outsole 22, exposed portions of the midsole 24 or portions of the shoe upper 28.

As shown in Figures 2 and 7, medial forefoot portion 14 has a radius of curvature 30 such that the medial forefoot portion is tangential with the outer surface 18 of the sole 10 and is formed between the outer surface and the side wall 26. As is shown in Figure 2, the extreme upper end 32 of the medial forefoot portion may form the side wall in the medial

-5- forefoot area of the sole. Preferably, the radius of curvature of the medial forefoot portion extends over approximately 90° from the outer surface to the side wall. As also can be seen in the figures, surface 18 is substantially planar. However, as is common and well known in the art, surface 18 is not typically purely planar. Rather, there are slight contours incorporated into the surface 18, over the length and width of the shoe, as well as recessed tread designs 20. However, aside from the recessed portions, surface 18 is substantially planar, at least in the area proximate to the medial forefoot portion 14.

Preferably, the medial forefoot portion 14 includes rectilinear channels 34 arranged substantially parallel to the longitudinal axis 36 of sole 10. As used herein, the term "rectilinear channel" means a channel having a substantially rectangular cross section. By providing the medial forefoot portion 14 with rectilinear channels 34, a rolling motion produced by a user wearing a shoe incorporating a sole 10, is performed smoothly since the rectilinear channels do not cause portions of the outsole 22 to protrude beyond the substantially planar outer surface 18. Furthermore, channels 34 allow foreign particles to be dislocated into the channels when the substantially planar outer surface 18 and/or the medial forefoot portion 14 contact a surface such as a court surface, thereby preventing slippage or loss of traction.

Preferably, the radius of curvature of the medial forefoot portion 14 is at least 12 mm. It has been found that a radius of curvature of at least 12 mm provides a sufficiently large area of contact between the sole 10 and a court surface that a typical user will be provided with enhanced traction and comfort during lateral lunging motions, as compared to the soles taught in the prior art.

In another embodiment of the present invention, the medial forefoot portion 14 is provided with a first radius of curvature at a first portion 38 of the medial forefoot area proximate to the arch portion 24 of the sole and a second radius of curvature at a second portion 40 of the medial forefoot portion proximate to the forward end 12 of the sole 10, where the radius of curvature at the first portion 38 is less than the radius of curvature at second portion 40. By providing the second portion 40 with a larger radius of curvature than the first portion 38, the area of contact generated by a rolling motion of the sole 10 in a direction that is substantially towards the front end 12 of the sole 10 and partially towards the

-6- medial portion 14 can be made larger than that which would be generated if the same radius of curvature was used for the entire length of the medial forefoot portion 14. This is because when the sole 10 is rotated over a surface such as a court surface in a direction purely laterally towards the medial forefoot portion, the area of contact generated between the sole 10 and the court surface extends over a substantial portion of the length of the medial forefoot portion 14 and over a portion of the radius of curvature of portion 14. However, when the shoe sole 10 is rotated in a direction substantially towards the front end 12 of the sole 10, the area of contact between the shoe sole 10 and a court surface extends only over a short portion of the medial forefoot portion 14 Therefore, by making the second radius of curvature larger than the first, the area of contact extends over a larger portion of the radius of curvature of portion 14, thereby tending to increase the size of the area of contact. Therefore, the amount of traction provided by the sole can be made to be more predictable since the size of the area of contact is made more consistent over the range of lunging-type motions a user might perform which include differing amounts of lateral and forward components.

Preferably, the radius of curvature of the medial forefoot portion is from about 12 mm to 18 mm. Furthermore, the radius of curvature between the first portion 38 and second portion 40 may gradually increase. For example the radius of curvature portion 38 may be 12 mm while the radius of curvature at position 42 may be 13 mm, 14 mm at position 44, 14 mm at position 46, 15 mm at position 48, 17 mm at position 50, 16 Y_ mm at position 52, 17 mm at position 54, 17 Vi mm at position 56, 18 mm at position 58 and 14 mm at position 60.

Preferably, the radius of curvature of the medial portion 14, increases progressively along the medial portion 14 of sole 10, from the smallest radius of curvature at portion 38 to the largest radius of curvature at portion 40. A progressively varying increase in the radius of curvature along the medial forefoot edge provides for optimal comfort during pushing off and turning motions from the side and front of the big toe during athletic activities. This design is particularly advantageous in court sports such as tennis, basketball or volleyball in which both running and twisting motions are required.

As shown in Figures 3, 4, 6 and 7, the shoe sole 10 may also include a cleated portion 62. In this embodiment, cleated portion 62 is formed of a plurality of cleats 64 provided on a resilient shroud adjacent the medial forefoot portion 14. By providing the cleated portion 62

-7- adjacent the medial forefoot portion 14, the shoe sole will enable a user to maintain traction on a turf surface even if traction between the shoe sole 10 and the turf surface has been lost and the sole has been rotated such that the cleated portion 62 comes into contact with the turf. Furthermore, cleated portion 62 provides extra protection when the shoe sole 10 is used in court sports where traction may ultimately be lost and the user's toe or the top portion of the user's foot adjacent the vamp area 66 may crash into a court surface.

According to another aspect of the invention, a method for manufacturing a sole for an article of footware includes forming a sole, such as sole 10, with a substantially planar outer surface, such as outer surface 18, as shown in Figures 1-7, forming a side wall on the outer surface, and forming a medial forefoot portion, such as portion 14, tangentially to the outer surface 18. Furthermore, the sole 10 may include the features described above with respect to Figures 1-7.

In the foregoing detailed description, reference has been made to a certain preferred embodiment of the invention. It is obvious that variants are possible without departing from the spirit of the invention as claimed below. The present application is based on U.S. Provisional Application No. 60/073,206 filed January 30, 1998, the entire contents of which is hereby expressly incorporated by reference.

-8-

Claims

Claims:

1. A sole for an article of footware, comprising: a substantially planar outer surface; a side wall attached to said substantially planar outer surface; a medial forefoot portion of said sole having a radius of curvature between said substantially planar outer surface and said side wall of said sole, said medial forefoot portion being substantially tangential to said substantially planar outer surface.

2. The sole according to Claim 1 , wherein said medial forefoot portion is curved over at least 90┬░.

3. The sole according to Claim 1, wherein said medial forefoot portion includes a first radius of curvature at a first portion proximate an arch portion of said sole and a second radius of curvature proximate a forward end of said sole wherein said second radius of curvature is larger than said first radius of curvature.

4. The sole according to Claim 1, wherein said radius of curvature is at least 12 mm.

5. The sole according to Claim 1, wherein said radius of curvature is from 12 to 18 mm.

6. The sole according to Claim 1, wherein said medial forefoot portion includes a plurality of rectilinear channels arranged substantially parallel to a longitudinal axis of said sole.

7. The sole according to Claim 1, further comprising an upper cleat portion, said upper cleat portion including a plurality of cleats provided adjacent said medial forefoot portion.

-9-

8. A sole for an article of footware, comprising: a substantially planar outer surface; a sidewall provided on a periphery of said substantially planar outer surface; and a medial forefoot portion including a first portion proximate to an arched portion of said sole having a first radius of curvature and a second portion proximate to a forward end of said sole having a second radius of curvature, said first radius of curvature being less than said second radius of curvature.

9. The sole according to Claim 8, wherein said medial forefoot portion is curved over at least 90┬░.

10. The sole according to Claim 8, wherein said radius of curvature is at least 12 mm.

11. The sole according to Claim 8, wherein said radius of curvature is from 12 to 18 mm.

12. The sole according to Claim 8, wherein said medial forefoot portion includes a plurality of rectilinear channels arranged substantially parallel to a longitudinal axis of said sole.

13. The sole according to Claim 8, further comprising an upper cleat portion, said upper cleat portion including a plurality of cleats provided adjacent said medial forefoot portion.

14. A method for manufacturing a sole for an article of footware, comprising the steps of: forming a sole with a substantially planar outer surface; forming a side wall on the sole; forming a medial forefoot portion of the sole with a radius of curvature that is substantially tangential to the substantially planar outer surface.

-10-

15. The method according to Claim 14, wherein said steps of forming a sole, forming a side wall, and forming a medial forefoot portion comprise molding.

16. The method according to Claim 14, further comprising forming the medial forefoot portion with a first radius of curvature at a first portion proximate to an arch portion of the sole and a second radius of curvature proximate to a forward end of the sole, wherein the second radius of curvature is larger than the first radius of curvature.

17. The method according to Claim 14, wherein the radius of curvature is at least 12 mm.

18. The method according to Claim 14, wherein the radius of curvature is from 12 to 18 mm.

19. A method for manufacturing a sole for an article of footware, comprising the steps of: forming a sole with a substantially planar outer surface; forming a side wall on the sole; forming a medial forefoot portion of the sole with a first radius of curvature at a first portion proximate to an arch portion of the sole and a second radius of curvature proximate to a forward end of the sole, wherein the second radius of curvature is larger than the first radius of curvature.

20. The method according to Claim 14, wherein the radius of curvature is at least 12 mm.

-11-