Description

Moulded shoe bottom with high anti-shock ventilation properties.

The present patent application relates to a moulded shoe bottom with high anti-shock properties, that is to say capable of absorbing the impact of the front part of the foot with the ground during walking. A dense series of flexible protuberances obtained when moulding the bottom is currently used to guarantee soft, elastically flexible support for the foot. The said protuberances are mostly configured as hollow spherical segments or thin cylindrical pegs with rounded tip, designed to subside or bend laterally every time the foot rhythmically discharges the weight of the body first on the metatarsal area of the foot and then on the toes. In spite of long-standing use and effectiveness, the said bottoms with "antishock" structure have often originated a disadvantage that affects the sole or so-called "intermediate sole" that covers the series of protuberances that project from the upper surface of the bottom. The said disadvantage consists in the formation of a web of wrinkles or folds that impair the perfect planarity of the intermediate sole which, in addition to being aesthetically unpleasant, may also cause an inconvenience for the foot plant, especially in case of delicate irritable skin, such as in children. The said inconvenience is basically due to the fact that the said series of protuberances offers a punctiform, not continuous or uniform support surface to the intermediate sole, so that folds are formed on the intermediate sole surface in the large empty spaces between support points, which increase in depth over time.

The wrinkle process is favoured by the natural perspiration of the foot in the hot season, since humidity tends to soften the material, which is normally real or synthetic leather, of the intermediate sole, which tends to self-modelling on its "punctiform support bed".

The main purpose of the present invention is to remedy the aforementioned inconvenience with a new one-piece moulded shoe bottom, which although

provided with an "anti-shock" structure characterised by a series of elastically flexible protuberances, provides a large continuous support surface to the intermediate sole. A further purpose of the present invention is to provide a moulded shoe bottom able to automatically generate forced air circulation inside the shoe during walking.

This effect has been obtained by using the said series of elastically flexible protuberances as pumping means designed to draw air from the shoe inside the bottom, from where the sucked air is ejected outside the bottom through a dedicated unidirectional valve.

In order to increase the pumping action and make the forced air circulation inside the shoe more energetic and efficacious, the bottom of the invention comprises two different and independent pumping chambers that use the same air valve to eject the sucked air outside. These and other purposes have been achieved by the shoe bottom of the invention, whose main characteristics are illustrated in the first claim. The shoe bottom of the invention comprises a dense series of protuberances that project from the upper surface of the half plant, in which each protuberance has a mushroom configuration, being formed of a vertical stem and an enlarged head.

The peculiarity of the stem consists in the fact that it is internally hollow, while the head is a sort of annular flange with square shape and rounded corners. The tubular configuration of the stems has allowed to make them thinner and deformable under the peak load, thus favouring deformation due to axial relaxation rather than flexural bending.

In other words, the said stems tend to be contracted as a bellows under compression, with bulging of the lateral wall rather than lateral flexion. The fact that each stem ends on top with a flat annular head with basically square shape allows to obtain a rather large support surface for the intermediate sole, and not of punctiform type, as in the known models of bottom, where the contact between the sole and the "protuberance bed" occurs in isolated points that coincide with the top of the said cylindrical pegs

with rounded tip or spherical hollow segments.

The capability of the said stems to be elastically contracted as a bellows under compression makes them suitable to provide the pumping action that in the current models of ventilated shoes is entrusted to special flexible inserts composed of soft pads with alveolar structure that are elastically deformed under compression.

The said inserts are obtained with different materials and moulding processes that are separated from the moulding process of the bottom where they are inserted. This means that an assembly operation is necessary between the bottom and the flexible inserts designed to provide the pumping action, while the bottom of the invention has a one-piece structure obtained from the same material during the same moulding process, which incorporates flexible means that are able to be elastically deformed under compression. For purposes of clarity, the description of the bottom of the invention continues with reference to the enclosed drawings, which are intended for purposes of illustration only and not in a limiting sense, whereby:

- fig. 1 is an axonometric view of the bottom of the invention with intermediate sole;

- fig. 2 is a sectional view with a vertical axial plane of one of the mushroom protuberances situated on the front half plant of the bottom of the invention;

- fig. 3 is a sectional view of the air valve with a longitudinal plane;

- fig. 4 is a sectional view of the heel of the bottom of the invention with a transversal plane IV-IV.

- fig. 5 is a sectional view of the air valve with a longitudinal plane according to an alternative embodiment.

With reference to the aforementioned figures, the bottom (1 ) of the invention is moulded from one piece of natural or synthetic rubber or other soft thermoformed flexible material normally used in the shoe industry to produce moulded bottoms. The bottom (1 ), which is provided with lower tread (1 a) and upper plant (1 b), is covered on top by an intermediate sole (B) provided with a dense series of small holes (F1 ), both on the front half plant and the heel, through which the

- A -

air contained inside the shoe can be sucked inside the pumping chambers obtained in the said bottom (1 ).

The upper plant (1 b) is provided - when moulding the bottom (1 ) - with a dense series of protuberances (2) that project from the bottom wall of a first cavity (3) with the same surface as the half plant of the bottom.

The cavity (3) is surrounded by a flat perimeter band (5) that runs along the entire edge of the bottom (1 ) in such a way to provide the edge of the intermediate sole (B) with an annular continuous uniform support surface. Each protuberance (2) has a mushroom configuration, characterised by a vertical stem (2a) with circular section and an enlarged head (2b).

More precisely, the stem (2a) is hollow, being similar to a tube with thin walls, able to get axially contracted under compression, with consequent bellows- like bulging of the cylindrical wall. The head (2b) consists in a sort of annular flange with square shape and rounded corners.

The protuberances (2) are situated in parallel position in such a way that very narrow empty spaces, preferably lower than 2 mm, are left between the enlarged heads (2b) with longitudinal or transversal direction. It must be noted that the thickness of the said head (2b) is not constant and is tapered away from the centre. This fact gives the head a certain flexional rigidity with respect to the bearing stem, so that the pressure exerted on the enlarged heads tends - also in case of asymmetric load distribution - to make the stem collapse axially, rather than bending downwards, as a shelf, the area of the head provided with the highest concentration of compression loads.

The heel (T) is provided with a second cavity (30), from which a collar (40) with basically rectangular section and rounded corners projects in central position, ending on top with an internal flange (41 ) with lower thickness than the lateral walls (40a) of the collar (40), as shown in fig. 4 .

Attention is drawn on the fact that the second cavity (30) is provided with a series of stiffening elements (42) extending between the internal wall of the chamber (30) and the external wall of the collar (40).

The height of the stiffening elements (42) decreases from the outside to the inside of the heel, in such a way to give high rigidity to the lower section (4Oa') of the lateral wall (40a), whose upper section (4Oa") is provided with higher elastic flexibility, same as the top flange (41 ) because of low thickness. It appears evident that when the weight of the body is discharged progressively on the heel during walking, the flange (41 ) is the first part to bend downwards towards the inside of the collar (40), whose lateral wall is subjected to elastic bulging on the upper section (4Oa") . In view of the above the collar (40) ensures an anti-shock impact for the heel of the foot.

The first and second cavity (3 and 30) act as pumping chambers due to the elastic deformation of the mushroom protuberances (2) and the collar (40), which are alternatively subjected to volume contraction and dilatation due to the pressure that is rhythmically exerted by the plant and the heel of the foot during walking.

One of the main peculiarities of the bottom (1 ) of the invention consists in the fact that the pumping chambers (3 and 30) are not communicating and use the same air valve (50), which consists in a three-way valve, with one outlet (51 ) and two inlets (52) in coaxial opposite position. The bottom (1 ) is provided in the plantar arch with a central housing (10) designed to contain the air valve (50) with a basically T-shaped configuration, whose horizontal wing is provided with the inlet conduits (52) that, being oriented one after the other, form a single conduit (53) that intersects the vertical outlet conduit (51 ). To avoid the backflow of the air from the outlet conduit (51 ) towards the inlet conduits (52), the valve (50) also comprises a pre-compressed spring (54) contained inside the said conduit (53) and positioned between closing means (55) that close the inlet conduits (52) respectively. The housing (10) communicates with the cavities (3 and 30) by means of corresponding longitudinal channels (61 and 62), while the bottom of the housing (10) is provided with a vertical through conduit (63) that exactly houses the vertical wing of the T-shaped valve (50).

Fig. 5 illustrates an alternative constructive embodiment of the air valve. According to this embodiment, although maintaining the T-shaped configuration, the air valve (500) is provided with two separate outlet conduits (51 a and 51 b) in parallel position in the vertical wing of the T-shaped valve (500).

The two outlet conduits (51 a and 51 b) communicate with corresponding air inlet conduits (52a and 52b) in opposite position in the horizontal wing of the T-shaped valve (500). The two air inlet conduits (52a and 52b) are closed by closing means (55) subjected to the action of corresponding springs (53).