Insole

Abstract

 An insole comprising an upper (2a) and a lower sheet (2b) of plastic material that are foot-sole shaped and joined along their perimeters in order to form a chamber (3) for containing a fluid (4), said insole (1) further comprising a longitudinal stiffening member (5) formed in a substantially central position in said chamber.

Description

[0001] The present invention concerns an insole.

[0002] More particularly, the invention concerns an insole that is provided with a chamber containing a fluid and is adapted to be inserted into footwear.

[0003] Insoles containing fluids for dampening the foot impact onto the ground are known since a long time.

[0004] Such insoles, thanks to the movement of the fluid imparted by the pressure exerted by the foot, carry out a massage of the user's foot sole and distribute the user's thereof on a wider surface, thereby improving the footwear support action and comfort.

[0005] One such insole is disclosed in U.S. Patent No. 4,567,677.

[0006] According to the teaching of said U.S. patent, an insole comprising a chamber filled with water and air is obtained by gluing two foot-sole shaped plastics sheets along their perimeters.

[0007] Narrowings are provided in the insole between the metatarsus region and the heel in order to channel the fluid circulation, said narrowings being obtained by gluing both plastics sheets in a number of points.

[0008] However, the insole according to the teaching of U.S. patent 4,567,677 however has the drawback of a reduced resistance to curling caused by stresses and movements transmitted to the insole by the foot during walking.

[0009] A first aim of the invention is therefore to solve the prior art problem by providing an insole that does not tend to become curled during walking.

[0010] Another drawback of the insole according to the teaching of the aforementioned U.S. patent is that, during walking, part of the fluid remains in the forward region of the insole, in correspondence with the empty region between the foot fingers and the metatarsus.

[0011] Such fluid stagnation point cannot be eliminated because no foot pressure displacing the fluid is present, unlike in other insole regions.

[0012] Under such conditions, the amount of circulating fluid is reduced, as consequently are the comfort and the massaging action of the insole.

[0013] A second aim of the invention is to overcome the above drawback of the prior art by providing an insole in which no fluid stagnation regions are formed during walking.

[0014] The above and other aims of the present invention are achieved by the insole of the invention equipped with a fluid-containing chamber including a longitudinal stiffening member, as claimed in the appended claims.

[0015] Further features of the invention will become more apparent from the description of a preferred but not unique embodiment thereof, shown by way of non limiting example in the accompanying drawings, in which:

• Fig. 1 is a plan view of the insole according to the invention; and
• Fig. 2 is a cross sectional view of the insole taken along line II-II of Fig. 1.

[0016] Referring to the drawings, a footwear insole 1 is made by joining two foot-sole shaped sheets of plastic material, namely an upper sheet 2a and a lower sheet 2b.

[0017] Such sheets 2a and 2b are joined along their perimeters by gluing, welding or other known technique so as to define a sealed chamber 3 adapted to contain a fluid 4 intended to absorb the impacts onto the ground during walking, to provide a more comfortable supporting surface and at the same time to carry out a massage thanks to the movement given to said fluid by the foot during walking.

[0018] Chamber 3 is divided into two lateral sectors 3a, 3b by a stiffening member 5, obtained by longitudinally joining a portion of upper and lower sheets 2a, 2b in the central region of the insole, by gluing, welding or other known technique.

[0019] Said stiffening member 5 forms a partition strip whose length is shorter than that of the chamber, so as to allow fluid communication between sectors 3a and 3b only through the forward and rear end portions 3c and 3d of said chamber 3.

[0020] Said stiffening member 5 makes insole 3 less flexible, thereby preventing its curling during walking.

[0021] Moreover said stiffening member 5 imposes a loop-shaped path to fluid 4, thereby improving the massaging effect of fluid 4 on the foot.

[0022] To avoid stagnation of fluid 4 near the forward portion of the chamber, corresponding with the empty region between metatarsus and foot fingers, said stiffening member 5 ends, in its forward portion, at a substantially circular widening 5a obtained by joining upper sheet 2a and lower sheet 2b.

[0023] A similar widening 5b is provided also at the rear edge of stiffening member 5, to narrow the passage for the fluid directed from one of sectors 3a, 3b of chamber 3 to the other.

[0024] Advantageously, a hole 7 is provided at each widening 5a, 5b to allow aeration of the user's foot.

[0025] The forward insole portion has no chamber therein, to allow it to be cut to measure in order to fit to the proper foot size.

[0026] To this aim, tracing lines 9 for the cut are provided on the insole and the measures said lines are related with are indicated; yet it is possible to provide insoles for each foot size which insoles have the advantage of a better correspondence between the chamber position and the foot.

[0027] To avoid skin cytotoxicity, sensitisation or irritation phenomena, the insole has been made by using biocompatible PVC sheets; yet use of different plastic materials, which can provide sufficient guarantee against the above mentioned skin sensitisation phenomena, is not excluded.

[0028] As to the fluid to be introduced in the chamber, it has been chosen out of the fluids having sufficient viscosity and lack of toxicity for the kind of application, such as a gel made of propylene glycol used in the field of insulation for foodstuffs.

[0029] Yet, even though the properties of thermal insulation of the insole are enhanced by said propylene glycol, it is to be underlined that such a choice is not mandatory, since any kind of fluid suitable for the purpose can be used.

Claims

1. An insole comprising an upper (2a) and a lower sheet (2b) of plastic material that are foot-sole shaped and joined along their perimeters in order to form a chamber (3) for containing a fluid (4), characterised in that said insole (1) comprises a longitudinal stiffening member (5) formed in a substantially central position in said chamber.

2. An insole according to claim 1, wherein said stiffening member (5) is obtained by gluing or welding said upper (2a) and lower (2b) sheets of plastic material over a length lower than the length of the chamber (3), in order to divide said chamber (3) into two sectors (3a, 3b) communicating only near the forward (3c) and rear (3d) ends of the chamber (3) corresponding to the metatarsus region and the heel, respectively, of the foot.

3. An insole according to claim 2, wherein said stiffening member (5) presents end widenings (5a, 5b).

4. An insole according to any preceding claim, wherein said sheets (2a, 2b) of plastic material are made of biocompatible PVC.

5. An insole according to claim 1, wherein said fluid (4) contained in said chamber (3) is a glycol, preferably an atoxic glycol.

6. An insole according to claim 2, wherein said stiffening member (5) has an aeration hole (7) at the centre of each widened end (5a, 5b).

Drawing