Background Art Currently, the trend of the footwear market is increasingly orientated toward the use of insoles made of soft material in order to improve wear comfort.

Such trend also affects the field of open shoes, such as beach mules, backless shoes, sandals, etcetera.

With regard to the mule product, it can be said that various approaches are currently followed for its manufacture.

In one of these approaches, for example, the mule is made of soft material with expanded material and is formed substantially by an upper, an insole and a sole with a tread.

In this case, first of all, the insole is produced by thermoforming and subsequent blanking from a sheet of a certain size.

Insoles in general are currently made of EVA (ethylene vinyl acetate), which ensures high standards of softness and strength and also allows to avoid absorbing water in the case of beach-type mules or sandals.

After its manufacture, the insole must be coupled to the previously formed sole.

Currently, the only method used to mate the insole and the sole is the interposition of adhesive between them.

The process for gluing the insole to the sole is extremely complex and difficult: in the case of EVA soles, for example, the two components are washed with solvents, the primer is applied, UV irradiation is performed in order to activate the primer, and adhesives are applied to the two parts; this is followed by the subsequent step of reactivation in an oven and finally by

coupling with subsequent pressing.

It is important that the mutual fixing of the insole and the sole be the strongest possible, since these shoes are used in extremely challenging environments, such as seawater, sand, chlorinated water of swimming pools, et cetera.

The upper can be manufactured separately and fixed simultaneously with the gluing of the insole and of the sole, optionally by inserting its lateral edges between the insole and the sole, or by gluing the lateral edges to the sides of the sole; generally, with this procedure the outer side of the insole is exposed and must therefore ensure an aesthetically acceptable finish.

Another possibility to fix the upper to the sole is mechanical and uses mushroom-shaped lugs that protrude from the edges of the upper and are inserted in suitable undercut recesses formed in the sole; in this last case, the insole is glued inside a pocket, which is shaped complementarily to said insole, and accordingly the outer side of the insole does not remain visible.

It can be noticed that this manufacturing system for open-type shoes has several drawbacks.

First of all, it is evident that the method for gluing the insole to the sole is extremely laborious, time-consuming and expensive, and more so for materials such as EVA, which require particular refinements during the adhesive bonding steps.

Secondly, the coupling between the insole and the sole provided by means of the adhesive is easily affected by external agents, which can accordingly reduce it.

Thirdly, the materials of these shoes are difficult to recycle, since it is not possible to separate the insole from the sole once they are no longer being used, said insole and sole being typically made of different materials that are often not compatible during recycling.

Moreover, the method for manufacturing the insole must lead to an

excellent lateral finish of the insole, since the insole is visible; this method therefore has higher costs than those required for lower-quality finishes.

Disclosure of the Invention The aim of the present invention is to provide an open-type shoe, particularly for mules, sandals, backless shoes and the like, that solves the problems noted in known types of open shoe.

Within this aim, an object of the present invention is to provide an open-type shoe, particularly for mules, sandals, backless shoes and the like, that reduces the steps for assembly of the various parts of the shoe.

Another object of the present invention is to provide an open-type shoe, particularly for mules, sandals, backless shoes and the like, that facilitates the shoe assembly operations.

A further object of the present invention is to provide an open-type shoe, particularly for mules, sandals, backless shoes and the like, that eliminates the operation for mutually gluing the insole and the sole.

Another object of the present invention is to provide an open-type shoe, particularly for mules, sandals, backless shoes and the like, that allows to recycle at least part of the shoe once it is no longer used.

Another object of the present invention is to provide an open-type shoe, particularly for mules, sandals, backless shoes and the like, that can be manufactured with known equipment and technologies.

This aim and these and other objects that will become better apparent hereinafter are achieved by an open-type shoe, particularly for mules, sandals, backless shoes and the like, which comprises an upper, an insole and a sole with a tread, said shoe being characterized in that said upper and said insole are fixed to said sole by way of mechanical coupling elements, which have portions arranged in opposition to parts of said sole that are undercut with respect to the foot resting surface.

Brief Description of the Drawings Further characteristics and advantages of the invention will become

better apparent from the following detailed description of preferred but not exclusive embodiments thereof, illustrated by way of non-limitative example in the accompanying drawings, wherein: Figure 1 is a side view of a first embodiment of the shoe according to the invention; Figure 2 is a sectional side view of the shoe according to the invention; Figure 3 is bottom view of a component of the shoe according to the invention; Figure 4 is a sectional front view, taken along the line IV-IV of Figure 1, of the shoe according to the invention; Figure 5 is a sectional front view, taken along the line V-V of Figure 1, of the shoe according to the invention; Figure 6 is a sectional side view of a portion of an embodiment that is alternative with respect to the first embodiment of the shoe according to the invention shown in Figures 1 to 5; Figure 7 is a sectional front view, taken along a sectional plane arranged in a forward region of the shoe, of a second embodiment that is alternative to the first embodiment of the shoe according to the invention; Figure 8 is a sectional front view, taken along a sectional plane arranged in a rear region of the shoe, of the same further alternative embodiment of Figure 7; Figure 9 is a side view of a portion of a third embodiment of the shoe according to the invention; Figure 10 is a sectional front view, taken along the line X-X of Figure 9, of the third embodiment of Figure 9 of the shoe according to the invention.

Ways of carrying out the Invention With reference to the figures, a first embodiment of an open-type shoe, particularly for mules, sandals, backless shoes and the like, according to the invention, is generally designated by the reference numeral 10.

The shoe 10 is in this case a beach-type mule and comprises an upper 11, made for example of thermoplastic material, an insole 12, preferably made of EVA (ethyl vinyl acetate), and a sole 13 with a tread also preferably made of EVA but with a higher density than the insole 12.

The upper 11 and the insole 12 are fixed to the sole 13 by way of mechanical engagement elements, which have portions arranged in opposition to parts of the sole that are undercut with respect to the foot resting surface, as will become better apparent hereinafter.

With reference to Figures 1 to 8, the insole 12 is sandwiched between the upper 11 and the sole 13.

Fixing between the upper 11 with the insole 12 and with the sole 13 is ensured by said mechanical engagement elements, which in this embodiment comprise four mushroom-shaped lugs 20, which extend downward in pairs from the two lateral edges 21 of the upper 11 and are monolithic therewith.

Each mushroom-shaped lug 20 is constituted by a stem 22 that protrudes from the upper 11 and by a head 23 that is larger than the stem 22.

The lugs 20 protrude from the insole 12 through first passages 24 provided in the insole 12; in particular, each first passage 24 and accordingly also each stem 22 (which is arranged within the passage 24) is inclined with respect to the extension of the sole 13.

The stem 22 also protrudes partially inside a second passage 24a, formed within the sole 13, which leads into a corresponding seat 25.

In practice, the mushroom-shaped lugs 20 pass through the insole 12.

The portion of the mushroom-shaped lug 20 that corresponds to the head 23 is arranged inside the seat 25.

The seat 25 is substantially shaped like the head 23 and opens onto the tread.

In practice, the bottom 26 of the seat 25 is substantially undercut with respect to the foot resting surface, and the head 23 ensures locking on the

bottom 26.

During assembly of the shoe, the mushroom-shaped lugs 20 are inserted in the first passage 24 and the second passage 24a, deforming them elastically.

This occurs because the heads 23 of the lugs are larger than the width of the passages 24 and 24a and are made of harder material than said passages.

Once insertion has occurred, the stem 22 is under traction, while the insole 12 is partially compressed between the edges 21 of the upper 11 and the sole 13.

The mechanical engagement elements further comprise a stud-shaped protrusion 30 that is monolithic with the insole 12, protrudes downward from it, and is substantially located on the portion of the shoe that corresponds to the heel of the foot.

The stud-shaped protrusion 30 is constituted by a stem 31, which protrudes from the insole 12, and by a head 32, which is larger than the stem 31.

The stem 31 lies inside a hole 33 that is formed in the sole 13 and leads into a corresponding recess 34.

The portion of the stud-shaped protrusion 30 that corresponds to the head 32 is arranged inside the recess 34.

The recess 34 is shaped substantially like the head 32 and opens onto the tread.

In practice, the base 35 of the recess 34 is substantially undercut with respect to the foot resting surface, and the head 32 ensures locking on the base 35.

The assembly process is similar to the one used for the mushroom- shaped lugs 20 of the upper 11.

Alternative embodiments of these shoes can comprise more of these stud-shaped protrusions 30, located for example at the tip of the shoe or in

other predefined positions.

With reference to Figure 5, in order to avoid slippages of the insole 12 with respect to the sole 13, the shoe 10 comprises three slot-shaped teeth 50, which protrude downward from the insole 12 and are accommodated in corresponding complementarily shaped containment holes 51 provided in the sole 13.

In particular, one tooth is arranged at the tip of the shoe, while the other two are arranged on the sides of the shoe.

Each tooth 50 further has, on its side, a knurling (not shown in the figures) that increases the adhesion of said tooth to its containment hole 51.

With reference to Figures 3 and 4, drainage channels 60 are provided in the shoe between the insole 12 and the sole 13.

In particular, the drainage channels 60 are formed by a grid of open slots 61 formed in the insole 12 and closed by the sole 13.

The drainage channels 60 comprise a plurality of drainage holes 62, which are arranged in an upper region in the insole 12 and are arranged substantially on the foot resting surface; the drainage channels 60 further comprise discharge openings 63 located on the lateral edge of the shoe.

Water enters the holes 62, passes through the drainage channels 60 and exits from the openings 63.

In particular, in this embodiment the drainage channels 60 are substantially flat and have a constant width and height along their extension.

Accordingly, the discharge openings 63 also all have substantially the same dimensions and are arranged along a decorative recess 65 of the lateral edge of the shoe.

Each discharge opening 63 is therefore arranged on the same plane as the corresponding drainage channel 60.

With reference to Figure 6, a mechanical locking element at the heel region of the shoe that is alternative to the stud-shaped protrusion 30 is constituted by a rivet-shaped body 40.

The rivet-shaped body 40 passes through the insole 12 and is formed by a central shaft 41 with two cambered end heads, respectively a first end head 42a arranged on the insole 12 and a second end head 42b arranged on the sole 13.

Each end head 42 is accommodated in a corresponding compartment; in particular, the first end head 42a is accommodated in a first compartment 43a, respectively on the insole 12, while the second end head 42b is accommodated in a second compartment 43b, respectively on the sole 13.

In this case also, the rivet-shaped body 40 is assembled by elastic deformation of the sole 13 and of the insole 12.

With reference to Figures 7 and 8, a further alternative embodiment of the fixing of the insole to the sole is characterized in that the insole, now designated by the reference numeral 212 (in this embodiment obtained by simple blanking from a previously thermoformed EVA sheet), also has, in addition to the interlocking with the mushroom-shaped lugs 20 and with any stud-shaped protrusions 30 or rivet-shaped bodies 40, portions of its own edges 212a that are interlocked within recesses 270 formed in the sole 213 and undercut with respect to the surface along which the sole lies.

In particular, the recesses 270 are C-shaped and are formed substantially along the entire upper perimeter of the sole 213.

With reference to Figures 9 and 10, a third embodiment of the shoe with respect to the preceding one or with respect to combinations of embodiments of the preceding one is designated by the reference numeral 300.

Such third embodiment is characterized in that the insole 312 and the upper 311 substantially constitute a single body; in particular, they are monolithic.

In this third embodiment, the mechanical engagement elements comprise four additional mushroom-shaped lugs 320, which are monolithic with the insole 312 and are substantially similar to the ones of the first

embodiment 10 (Figures 1 and 4).

The mushroom-shaped lugs 320 protrude downward, substantially in pairs, at the lateral edges 321 of the upper 311.

Each mushroom-shaped lug 320 is constituted by a stem 322 that protrudes from the upper 311 and by a head 323 that is larger than the stem 322.

Each stem 322 is arranged so as to pass through a corresponding passage 324 of the sole 313 and ends in a corresponding seat 325.

The portion of the mushroom-shaped lug 320 that corresponds to the head 323 is arranged inside the seat 325.

The seat 325 is substantially shaped like the head 323 and opens onto the tread.

In practice, the bottom 326 of the seat 325 is substantially undercut with respect to the foot resting surface, and the head 323 ensures locking on said bottom 326.

The assembly of the shoe is substantially similar to the preceding embodiment.

With respect to the first shoe version, in this second version 300 there is an alternative arrangement of the drainage channels.

In this version, the lateral recess of the shoe is now designated by the reference numeral 365.

The recess 365 is shaped so that the drainage channels, if traced as in the case of the first embodiment (Figures 3 and 4), would have to curve upward, since the discharge openings would be located higher than the planar extension of said channels, thus preventing the outflow of the water.

In this embodiment, instead, the discharge openings, now designated by the reference numerals 363, are discharged downward to the same height as the drainage channels 360.

It should be noted that the shoe of this last embodiment is substantially made of two main parts (upper-insole and sole), while the first described

version is substantially made of three main parts (upper, insole and sole).

It should be noted that the various embodiments of the first type described (the three-part shoe) are substantially applicable also with a shoe described in the second type (two-part shoe); in practice, the slot-shaped teeth 50 and the rivet-shaped body 40 can be applied also to the second shoe type (two-part shoe).

In practice it has been found that the invention thus described solves the problems noted in known types of open shoe; in particular, the present invention provides an open-type shoe, particularly for mules, sandals, backless shoes and the like, that reduces the steps for the assembly of the various parts of the shoe.

Moreover, the present invention provides an open-type shoe, particularly for mules, sandals, backless shoes and the like, that facilitates the operations for assembling the shoe.

It should be noted that eliminating the operation for mutually gluing the insole and the sole eliminates a long and unhygienic process step, which requires considerable labor and dedicated equipment and is in practice an extremely expensive production step.

Moreover, the present invention provides an open-type shoe, particularly for mules, sandals, backless shoes and the like, that allows drainage of the water from the foot resting surface, thus preventing losses of grip on the part of the foot.

It should be noted, in this regard, that this shoe allows to provide easily drainage channels between the sole and the insole, while in the case of gluing this is very difficult; in the case of gluing of the two parts, the provision of drainage channels is in fact made difficult owing to the fact that the adhesive is"brushed"onto the two surfaces in contact, with the tangible risk of introducing adhesive in said channels, obstructing them.

Moreover, it is noted that with this invention the insole has an improved aesthetic finish, since it can be produced by injection-molding, a

method that ensures a better finish than blanking from a thermoformed sheet.

Moreover, the present invention provides an open-type shoe, particularly for mules, sandals, backless shoes and the like, that allows to recycle the shoe once it is no longer used.

In practice, the materials employed, so long as they are compatible with the specific use, as well as the dimensions, may be any according to requirements and to the state of the art.

The disclosures in Italian Utility Model Application No.

PD2002U000061 from which this application claims priority are incorporated herein by reference.