SOLE STRUCTURE OF A SPORTS SHOE

Abstract: The invention concerns a sole structure of a sports shoe comprising a wearing sole (1) and an intermediate layer (2) and also a cushioning and supporting structu­ re (3, 4, 5) between them. The mentioned cushioning and supporting structure comprises a flexible toe part (5) extending virtually form the tip of the shoe to the ball area of the foot, a resilient heel part (4) taper­ ing wedgelike from the rear edge of the shoe towards the tip of the shoe and extending at least over the heel area as well as a body piece (3) fitted above the heel part (4) and extending virtually from the rear edge of the shoe to the ball area of the foot or to the zone (A) becoming against the heel and the arch.

Description: The invention concerns a sole structure of a sports shoe comprising a wearing sole and an intermediate layer and a cushioning and supporting structure between them such as described in US-A-40 30 213. Two basic claims have been made for running shoes, especially those for marathon and other long-distance running races. The principal task of the shoe is to help the running act so that the runner moves forward as economically as possible. The other task of the shoe is to protect the feet for running exertions, so that the conditions for the runner's performance may be pre­ served also to the latter part of the running race. To achieve the aforementioned functions many different shoes have been developed with resilient sole structure to reduce the extertions directed to the runner's feet. Resilience of the sole can be obtained in many different ways. For example an air cushion structure can be used or the sole can be made of several layers one upon the other, the hardness and density of which vary to achieve a progressive flexibility. A disadvantage in the already known shoes is, however, that during the running act when the shoe is placed against the running ground, remarkable and unnecessary deformations take place in the shoe sole, so that the shoe sole is returned to its original form only when the shoe is in the air. The run­ ner wastes in this way plenty of energy only for the deformation of the shoe sole. The purpose of this invention is to achieve an entirely new sole structure for a sports shoe, by which the afo­ rementioned disadvantages are eliminated. This goals achieved by a sole structure such as defined in claim 1. Of the advantages of the invention in regard to already known arrangements can be mentioned among other things the following ones. The sole structure according to the invention receives efficiently the impact directed to the runner's heel in the landing phase of the foot. In the so-called rolling phase of the foot the sole struc­ ture supports effectively the arch, on account of which the extertions directed to the foot are lighter. In the take-off phase of the foot the unnecessary sliding of the shoe can very effectively be eliminated by the sole structure according to the invention. The invention will now be described in detail with refe­ rence to the figures of the accompanying drawing without limiting the invention to the adaptation example shown there. Figure 1 shows a sole structure according to the inven­ tion as a schematic longitudinal section. Figures 2A, B and C show schematically the function of the sole structure according to the invention in diffe­ rent phases of the running sequence. A sole structure of a sports shoe according to the in­ vention shown in the figure 1 comprises a wearing sole 1, intermediate layer 2 and also a cushioning and sup­ porting structure between them comprising a body piece 3, heel part 4 and toe part 5. The body piece 3 is composed of rigid and strong material and it is fitted to the area A in the sole structure of the shoe becoming against the heel and the arch. The body piece 3 extends thus from the rear part of the shoe essentially to the ball of the feet. The body piece 3 is composed of so rigid material, that the shoe is at the area of the body piece 3 virtually inflexible. During running the body piece 3 keeps its form supporting the arch, so that the extertions directed to the the foot remain lighter. The body piece is formed in such a way, that the height of its longitudinal sec­ tion grows from the rear edge of the shoe towards the front part of the shoe in a suitable way mainly linear­ ly and that the said sectional height is at its greatest value at the front edge of the heel part of the shoe or in front of it. The heel part remaining between the body piece 3 and the wearing sole 1 is therefore wedgelike in its shape, so that the height of the heel part 4 in the longitudinal section is at its greatest value on the area of the rear part of the heel. By the heel part 4 a necessary resi­ liency and shock absorption ability is thus achieved in the landing phase of the foot and therefore the heel part is composed of a flexible, preferably light and foamy material. Any material with sufficient flexibility and shock absorption ability can naturally be used in the heel part 4. Therefore in the heel part 4 can be used e.g. an air cushion structure, layer structure or equi­ valent. It is stated before, that the height of the longitudi­ nal section of the body piece 3 or the thickness of the body part grows from the rear edge of the shoe towards the front part mainly linearly. Said change of thickness is not, however, necessarily linear, but the junction point of the body piece 3 and the heel part 4 may also be curved. Then can also the surface becoming against the heel part 4 of the body piece 3 be downwards convex and the upper surface of the heel part 4 correspondingly upwards con­ cave. Said surface of the body piece 3 can also be con­ cave, in which case the upper surface of the heel part 4 is correspondingly convex. Radii of curvature of said surfaces are anyhow great, so that the thickness varia­ tions of the body piece 3 and the heel part 4 are almost linear. The toe part 5 between the wearing sole 1 and interme­ diate layer 2 in front of the body piece can advantage­ ously be made of the same resilient material as the heel part 4. The toe part 5 extends from the tip of the shoe to the ball area of the foot or to the zone of the take-­ off power. Because the mentioned toe part 5 has been made flexible, a better grip or greater frictional for­ ces are achieved between the wearing sole 1 and the running ground. Then the unnecessary sliding is avoided in the take-off phase and the runner may move forward more rapidly. To obtain a suitable flexibility, the toe part 5 can also be composed of several materials like the heel part 4. Figure 1 shows that the body piece 3 is also at its front part wedgelike tapering. This is not, however, necessary for the invention, but advantageous, because by the said form of the front end of the body piece 3 it is easier to control the bending point of the shoe. If the front part of the body piece 3 is also wedge-­ shaped, can the mentioned wedge-shapeness be accomp­ lished in the same way as in the rear part of the body piece 3. The surface of the body piece 3 becoming against the toe part 5 can thus be linear or curved. More important than the form of the front part for the shape of the body piece 3 is, however, the fact, that it is according to the figure 1 wedgelike tapering to­ wards the rear part of the shoe. By this arrangement the wedge-shaped form of the heel part 4 is achieved as shown in the figure 1, and due to this the shock absorp­ tion ability of the shoe is at its greatest just at the rear part of the shoe. Figure 1 shows also that the body piece 3 extends at its thickest zone in the intermediate layer 2 to the wearing sole 1. Moreover the body piece 3 must naturally be with its full length fixed to the in­ termediate layer 2 in order to make the best possible arch supporting. It is also described above, that the body piece 3 is es­ sentially rigid material and the heel part 4 and the toe part 5 essentially flexible material. In this respect the most important thing is however, that the stiffness of the body piece 3 is virtually greater than the stiffness of the mentioned heel part 4 and toe part 5. In perfor­ med tests the necessary stiffnesses and resiliecies have been obtained by materials, by which the hardness of the body piece is 50 Shore A and correspondingly of the heel part 4 and toe part 5 35 Shore A. In the following reference is made to figures 2A, B and C and the function of the sole structure according to the invention will be described in different phases of a running step. In the figure 2A the landing or impact phase of the foot is presented. Especially long-distance runners as marathon runners and equivalent begin their running step so that either the middle part of the sole or backwards from it is first hit to the ground. Only very few long-distance runners make their steps with balls of the feet. The farther the landing point is, the less flexibility is needed in the shoe to absorp the impact forces, and the greater part of the impact is received by the runner's own muscles. Therefore the heel part 4 of the sole structure according to the in­ vention is made as a wedge getting backwards thicker. The more rear then the first impact point is, the grea­ ter is the cushioning ability of the sole structure. The figure 2B shows the rolling phase of the foot. In this phase the runner's center of gravity downwards is stopped and the foot prepares to take-off upwards and forward. The greatest pressure is in this case direc­ ted to the arch zone and the sole structure of the shoe must not because of this become too flat, so that the runner would not lose his energy to the deformations in the sole structure. The shape of the body piece 3 according to the invention has important effect to the function of the rolling phase helping to begin the take-off phase. Because the rigid body piece 3 extends at its thickest zone from the intermediate layer 2 to the wearing sole 1, the shoe does not therefore become flat, but the foot may easier and quicker turn to the take-off phase. The figure 2C shows the take-off phase of the foot. In this phase the flexible energy stored in the muscles and the thrust of the foot are transferred through the shoe to the running ground. In this phase it is impor­ tant that as great friction force as possible is formed between the shoe and the ground, so that the take-off moves the runner forward. In the sole structure accor­ ding to the invention this is influenced by the flexib­ le material of the toe part 5 under the toe zone and the ball of the feet, thickness of the sole structure on the area of the toe part 5 as well as quality of the wearing sole 1. Physically it is important, that during the whole take-off phase the contact surface between the shoe and the ground is as large as possible. In practice the friction force increases proportionately to the contact area. Therefore the wearing sole 1 in the sole structure according to the invention is smooth and un­ perforated at the range of influence of the take-off force or under the toe part 5. The performed tests have shown, that by the sole structure according to the in­ vention or by the unperforated wearing sole 1 and resi­ lient toe part 5 a remarkably better direction and greatness of the take-off force than by conventional structures are achieved in the take-off phase. The invention has been described above taking an example with reference to the figures of the accompanying draw­ ing. This has not, however, been done to limit the scope of the invention only for the example presented in the figures, but many changes are possible within the scope of the principles of the invention set forth in the following claims.

Claims: 1. A sole structure for a sports shoe, comprising an intermediate layer (2), and a cushioning and supporting structure (1,3,4,5) situated underneath said intermediate layer (2), wherein said cushioning and supporting structure (1,3,4,5) comprises a wearing sole (1) having a wearing surface adapted during use to come into contact with the ground underneath said cushioning and supporting structure (1,3,4,5), a flexible toe portion (5) substantially extending from a forward tip of the shoe to an area thereof corresponding to the area which receives a ball of a foot, a resilient heel portion (4), tapering in a wedge-like manner from a rear edge of the shoe towards the forward tip of the shoe and extending over at least an area of the shoe for receiving a heel of the foot, and a body portion (3) situated above said heel portion (4) and fixed to said intermediate layer (2) over the entire length of the upper surface of said body portion (3) and to said toe and heel portions (5,4) over the lower sur­ face thereof, said body portion (3) having a variable thickness in the direc­ tion of the length of the shoe, the thickness being greatest at the front edge of the heel part of the shoe or in front of it, characterized in that the body portion (3) extends substantially from the rear edge of the shoe to the area for receiving the ball of the foot over a zone (A) adapted to fit against the heel and an arch of the foot so that the flexible toe portion (5) is fixed straight to said intermediate layer (2) and to said wearing sole (1) at least in the area of the forward tip of the shoe, that said body portion (3) is substantially stiffer and harder than said heel portion (4) and said toe portion (5), and that the contact surface of said wearing sole (1) is substantially flat 2. The sole structure according to claim 1, characterized in that the surfaces of said body portion (3) and of said heel portion (4) abut­ ting against one another are substantially flat. 3. The sole structure according to claim 1, characterized in that the surfaces of said body portion (3) and of said heel portion (4) abut­ ting against one another are substantially curved. 4. The sole structure according to any of the preceding claims, characterized in that said body portion (3) tapers in a wedge-like manner from a front edge of said heel portion (4) to the area for receiving the ball of the foot 5. The sole structure according to claim 4, characterized in that the surfaces of said body portion (3) and of said toe portion (5) abutting against one another are substantially flat. 6. The sole structure according to claim 4, characterized in that the surfaces of said body portion (3) and of said toe portion (5) abutting against one another are substantially curved. 7. The sole structure according to any of the preceding claims, characterized in that the hardness of said body portion (3) is about 50 Shore A and the hardness of said heel portion (4) and of said toe portion (5) is about 35 Shore A.

Inventors: TIITOLA, ANTTI-JUSSI
Applicants: KARHU-TITAN OY
Application year: 1986
Main classification: A43B13
IPC codes: A43B13, A43B5