Improved footwear bottom designed to generate forced air circulation inside the shoe.

The present patent application for industrial invention relates to an improved moulded footwear bottom designed to automatically generate forced air circulation inside the shoe during walking.

In recent years the market has seen an increasing number of the so-called ventilated shoes, which ensure continuous forced aeration of the foot due to the presence of special moulded bottoms with box-shaped structure, which are able to take air from the inside of the shoe and convey it under pressure into a discharge channel obtained in the said box-shaped structure, ending with an ejection valve usually situated along the sides of the heel. The operating principle of all models of ventilated shoes is to create an intake chamber under the forefoot and use the pumping action that is spontaneously performed by the foot during walking, due to the fact that during the impact with the ground the weight of the body is first discharged on the heel and then gradually distributed on the half-sole, until it is concentrated on the toes, when the foot is raised to make another step forward.

Starting from the observation of the foot articulated movement during walking, moulded bottoms have been produced, being characterised by a front cavity that houses a bearing element that can be elastically deformed under pressure, such as for example pads with alveolar structure, providing at the same time a connection channel between the front cavity and the air discharge valve on the sides of the heel.

The front cavity is always open, being designed to be closed on top by the intermediate sole, in case of assembled shoes or by the upper in case of moccasins. In any case, the use of the said bottoms requires the intermediate sole or the upper that separates the inside of the shoe from the bottom to be provided with a dense series of small holes on the half-sole, which ensure communication between the inside of the shoe and the air intake chamber, in

such a way that, every time the foot touches the ground, the air contained in the front cavity is pushed into the channel and ejected outside by means of the discharge valve, while every time the foot is lifted from the ground , the air contained in the inside of the shoe is sucked into the air intake chamber, with consequent air exchange in the inside of the shoe and beneficial cooling of the foot by means of a fresh air flow.

In order to generate a more energetic and efficacious air circulation, the applicant has recently proposed and patented a bottom provided with two separate chambers, the first chamber being situated on the front of the half- sole and the second chamber on the back of the heel, in which the first chamber has a pumping action with respect to the inside of the shoe, whose air is sucked into the first chamber and from there is pushed into the second chamber, whose lateral walls are provided with at least one discharge hole that houses a monodirectional valve that permits to eject air from the second chamber outside and prevents a suction flow with opposite direction.

The two chambers are hermetically separated by a transversal partition provided with at least one hole for a monodirectional valve that permits to transfer air from the first to the second chamber. In order to increase the said pumping action and improve the energy and efficiency of the forced air circulation inside the shoe, the applicant has devised the improved bottom of the invention, which comprises two different and independent pumping chambers that use the same discharge opening to eject air outside. An additional purpose of the present invention is to devise a bottom characterised by extreme flexibility, which can be used either at high performance level or in a limited operating mode according to the different requirements or preferences, meaning that it only has one pumping chamber, either the front or the back chamber, instead of two pumping chambers; in any case, the provision of these two constructive versions with limited operating mode does not require to adjust the structural configuration of the bottom, which remains unchanged compared to the one used in the high- performance version.

Finally, another additional purpose of the invention is to devise a moulded footwear bottom designed to generate forced air circulation inside the shoe during walking, which is provided with elastically deformable inserts in the said pumping chambers in order to generate a strong suction effect. These and other advantages offered by the invention will become more evident following to the description below that continues with reference to the enclosed drawings, which are intended for purpose of illustration only and not in a limiting sense, whereby:

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

- fig. 2 is an axonometric top view of the bottom of the invention after assembling, without the intermediate sole;

- fig. 3 is a section of fig. 2 with a vertical plane passing through the longitudinal axis of the bottom. With reference to figure 1 , the bottom (1) of the invention comprises a one- piece moulded sole (2) and two elastically deformable inserts (3 and 4) designed to be housed in corresponding cavities (5 and 6) obtained on the upper side (FS) of the sole (2). More precisely, the sole (2) has an ordinary box-shaped configuration, which comprises a walking surface (P) with central cavity (M), a half-sole (A), a heel (T), a perimeter border (S) and two cavities with different depth and shape, a front (5) and a back (6) cavity, separated by a central area (Z) provided with a grid of stiffening partitions (7). More precisely, the front cavity (5) basically occupies the entire half-sole (A) and the back cavity (6) basically occupies the entire heel (T).

The bottom (1 ) is closed on top with an intermediate sole (B) provided with a series of small holes (F1) and an opening (F2) that provide communication between the inside of the shoe and the cavities (5 and 6). More precisely, the first series of holes (F1) is concentrated on the half-sole (A) and favours the air intake from the inside of the shoe towards the front cavity (5), and the opening (F2) is situated on the heel (T) and favours the air intake from the inside of the shoe towards the back cavity (6).

The cavities (5 and 6) act as pumping chambers because of the inserts (3 and 4) they contain, which are alternatively subjected to volumetric contraction and expansion due to the pressure that is rhythmically exerted on them by the foot plant and heel during walking. One of the main characteristics of the bottom of the invention consists in the fact that the said pumping chambers (5 and 6) do not communicate and use the same discharge chamber, which consists in a cylindrical bell (8) obtained in the centre of the said grid of partitions (7), with lower opening (8a) situated in the cavity (M) on the walking surface (P). It must be noted that the opening (8a) is covered with a mesh or a protection transpiring membrane (R) designed to prevent mud, soil or other foreign bodies from infiltrating and being trapped inside the bell (8), thus impairing the correct energetic air discharge outside.

The lateral walls of the cylindrical bell (8) are preferably provided with two diametrically opposite points (P1 and P2) with low thickness, where the suitably flutebeak-shaped point of a monodirectional valve can be easily inserted and held in place, in order to eject the air sucked from the inside of the shoe into the discharge chamber.

More precisely, a first valve (9) is inserted between two longitudinal partitions (7a) immediately before the bell (8), with the pointed beak (9a) inserted in the wall of the bell (8), and a second valve (10) is inserted between the two longitudinal partitions (7b) immediately behind the bell (8) with the pointed beak (10a) inserted in the wall of the bell (8).

The deformable insert (3) housed inside the front cavity (5) consists in a plastic moulded soft pad (11), whose section with a longitudinal vertical plane has a sinusoidal profile with square bends, as shown in the enlarged detailed view of fig. 3.

The said profile increases the aforementioned pumping effect.

The lower surface of the pad (11) is provided with a pair of grooves (12) that converge towards the centre on the back and act as channels to convey the sucked air towards the pair of longitudinal partitions (7a) between which the first valve (9) is inserted.

As a matter of fact, the bends of the pad (11 ) are provided on the bottom with a dense series of small holes (13) designed to transfer the air sucked from the inside of the shoe under the pad (11) and discharge it in the discharge chamber through the ejection valve (9). According to the preferred embodiment described in the enclosed figures, the deformable insert (4) housed in the back cavity (6) is composed of a plastic moulded hood soft (14), designed to be externally centred on a rigid collar (15) that protrudes from the centre of the back pumping chamber (6). More precisely, the hood (14) is provided on top with a very short section (14a) with reduced width, designed to be engaged and held inside the corresponding opening (F2) obtained on the intermediate sole (B), as shown in fig. 3.

The hood (14) is provided with a flat top wall with a dense series of small holes (14b) designed to suck the air of the inside of the shoe into the hood (14) and discharge it into the discharge cell through the ejection valve (10). In addition to acting as centring pin of the hood (14), the rigid collar (15) acts as stop for the pressing travel of the hood, (14), in such a way that the maximum contraction of the hood (14) under pressure, and consequently the power of the pumping effect, can be adjusted as desired by suitably dimensioning the height of the collar (15).

Evidently, the bigger the size of the shoe, the higher will be the weight discharged on the hood (14) every time the heel of the foot touches the ground.

Moreover, it must be noted that the deformable insert (4) has an anti-shock function that remains also when the second valve (10) is not mounted, considering the pumping action of the pad (11) as sufficient. The declaration contained in the premises, according to which one of the advantages offered by the bottom of the invention is the possibility to use it according to the specific requirements or preferences, either at top performance level or in limited operation mode, by offering only one pumping chamber instead of two, is now better understood. In order to increase the shock-absorbing effect, the base (15a) of the rigid

collar (15) slightly protrudes under the heel (T), and the lateral walls (15b) are surrounded by a concentric pair of annular gaps (16a and 16b), the internal gap being closed on the bottom and the external gap being closed on the top, thus forming a sort of elastic serpentine bellows that allows the rigid collar (15) to make alternated vertical travels.

Evidently, every time the heel (T) touches the ground, the collar (15) is forced to raise inside the cavity (6), thus elastically deforming the said bellows, which immediately returns to the idle position, with consequent ejection of the base (15a) as soon as the interference with the ground has ceased. Finally, attention is drawn on another advantage of the bottom of the invention, according to which the beaks (9a and 10a) of the ejection valves (9 and 10) are completely protected and hidden inside the discharge cell, unlike the current models of ventilated bottoms in which the said beaks are unpleasantly visible - and also exposed to risk of clogging - on the lateral walls of the bottom, being normally situated on the side or the back of the heel.