GB2102669A

GB2102669A - Insoles

Info

Publication number: GB2102669A
Application number: GB08121512A
Authority: GB
Inventors: Maud Kjellen
Original assignee: Svenska Tobaks AB
Current assignee: Svenska Tobaks AB
Priority date: 1981-07-13
Filing date: 1981-07-13
Publication date: 1983-02-09

Abstract

An insole (1) for footwear, comprises a first sheet of material (2), a plurality of gas-filled cells (4-7) each having an upper, flat surface (9) lying in a common plane, and a second sheet of material (3) firmly fixed over the surfaces 9. <IMAGE>

Description

SPECIFICATION An insole for footwear Technical Field The present invention relates to an insole for footwear, comprising a sheet of material having fixedly disposed over one surface thereof closely arranged gas-filled, mutually independent cells adapted to resiliently absorb forces created by the feet of a person wearing said footwear.

State of the Art The U.S. Specification Serial No. 3 589 037 teaches an insole of the aforementioned kind in which the cells are of hemispherical shape. The pressure absorbing surface exhibited by such cells is quite insignificant and there is a danger that the cells will rupture in those areas where they are subjected to the greatest load when worn, thereby subjecting the heel as a whole to impact forces which result in leg ailments. The hemispherical cells can give rise to an unpleasant feeling through their punctilinear abutment with the sole of the foot.

Disclosure of the Invention The object of the invention is to provide an insole having cells which together form a planar surface against which the foot may lie and each of which exhibits a maximal pressure-absorbing surface so as thereby to eliminate the sensation of goose-pimples, which hemispherical cells give rise to, and the danger of individual cells rupturing.

The main characterizing features of the invention reside in that the cells have an upper planar surface remote from said sheet of material in a mutually common plane; and in that a further sheet of material is brought onto said planar surfaces and firmly fixed thereto paraliel with the first mentioned sheet of material.

The gas-filled cells are subjected to pressures of differing magnitudes along the sole of the foot, and consequently the thickness of the insole and the size of the cells can be decided with respect to these forces. Practical tests have shown that cells of substantially cylindrical configuration and having a diameter of 5-10 mm and a height of 3-5 mm and being spaced at a smallest distance apart of 0.5-4 mm are well able to absorb the highest impact forces which might occur when a person of average weight walks on a hard surface.

The aformentioned dimensions vary in dependence on the shape of the cells and the pressure of the gas therein. Normally the gas comprises air at atmospheric pressure, although it is also conceivable to hold the cells under a pressure which is higher than atmospheric.

The space between respective cells and the two sheets of material is filled with air or an elastic material, such as foam rubber or foam plastics, and the cells have walls which consist either totally or partly of a flexible material, such as an extensive plastics material.

Brief Description of the Drawings Figure 1 is a plan view of an embodiment of an insole according to the invention, with part of the upper sheet of material removed, and Figure 2 is a sectional view taken on the line Il-Il in Fig. 1.

Fig. 1 illustrates an insole 1 for footwear.

As will best be seen from Fig. 2, a plurality of closed cells filled with air, e.g. cells 4, 5, 6, 7, are arranged between a first sheet 2 and a second sheet 3, said sheets having the shape of a foot. In the Fig. 2 embodiment, the profiled sheet 2 comprises a gas-impremeable plastics material and the cells 4, 5, 6, 7 have been formed by exposing a sheet of flexible plastics material to a vacuum so as to form cylinders having a cylindrical wall 8, a top wall 9 and an open bottom 10. The open bottom of respective cells has then been closed in a gas-sealed manner by means of the profiled sheet 2. The vacuum-shaped sheet can be joined to the profiled sheet 2 by welding parts 11 located between respective adjacent cells to said profiled sheet 2 in a gastight fashion, or by means of a thermosetting binding agent.The profile sheet 3 is placed on the end-wall surfaces 9 of the cylindrical cells, said surfaces lying in a common plane, and is suitably impermeable to gas although it may be permeable to air so as to provide ventilation for the sole of the foot. Thus, the sheet 3 may comprise a continuous, gasimpermeable sheet of plastics material, a perforated plastics sheet, a fabric made of natural or artificial fibers, a fabric-lined plastics sheet, etc.

In the illustrated embodiment, the closed cells cover the whole surface of the insole and are of mutually equal size, and the profiled sheet 1 is of uniform thickness, Normally, the greatest pressure is exerted within the forward region of the foot, and the cells within this region must be dimensioned so that the wearer walks or lifts heavy objects, etc., the pressures arising therefrom can be elastically absorbed, i.e. in normal cases the profiled sheets 2, 3 shall not be urged together so as to contact each other, in which case a rigid support or abutment is formed, which can cause harm to the leg of the wearer.

As a rule, the pressure within the central part of the foot is less, and the cells within this region need not therefore be dimensioned to absorb as high pressure forces as the cells in the forward region of the foot. Although it is more convenient from a manufacturing aspect to have the same cell pattern and the same cell size throughout, it is also possible to provide cells of low supporting power within those regions of the insole where pressures are not so high, and cells of high supporting power in those regions where pressures are high.

The shape of the cells may vary within wide limits, and said cells may, for example, comprise mutually adjacent cubical gas-impermea ble and gas-filled bodies arranged over the whole surface of the insole or over the parts of said surface.

In order to improve the wear strength of the insole, futher sheets of material may be mounted on the sheet or sheets joined with the cells. The insole may also be constructed of a plurality of layers of cells, arranged between pairs of sheets, It is also possible to form the cells with double sheets, which are welded firmly to the sheet 2.

Claims

1. An insole (1) for footwear, comprising a first sheet (2) having fixedly arranged on one surface thereof in close adjacent relationship a plurality of gas-filled mutually independent cells (4-7) which are mutually independent of one another and which are adapted to resiliently absorb forces directed against the foot of the wearer, characterized in that the cells have an upper flat surface remote from said first sheet (2) and lying in a common plane; and in that a second sheet (3) is placed upon said first sheet (2) parallel therewith, and firmly joined to said flat surfaces.

2. An insole according to Claim 1, characterized in that the cells are of cylindrical shape.

3. An insole according to Claim 1, characterized in that the cells are of cubical shape.

4. An insole according to any one of Claims 1-3, characterized in that the pressure-absorbing ability of the cells (4-7) varies over the surface of said insole.