Patent Description:
In general, the present invention relates to the field of tire inserts for vehicle wheels, particularly, but not exclusively, for off-road vehicles, such as dirt bikes and motorcycles, enduro bikes, and the like.

At least in the field of the aforesaid off-road vehicles, the possibility is known to insert polymer foam inserts inside the tires to limit puncture phenomena and to improve the dynamic performance of the tire during the stresses received from the terrain during the ride. According to the prior art, said insert type comprises annular-shaped inserts shaped to adhere and push at least partially on the inner walls of the tire to impart the appropriate dynamic performance during operation. Some examples of tire inserts of the prior art are disclosed in documents <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, XP055907979 and <CIT>.

Typically, such inserts are toroidal in shape with a solid circular cross-section.

Inconveniently, the very fact that said type of insert is in contact with the inner wall of the tire affects tire performance in a manner dependent on both tire inflation pressures and the working position of the wheel relative to the road, not guaranteeing homogeneity of performance as a consequence.

Furthermore, said type of insert is not suitable for use also on normal road vehicles. Indeed, the type of inserts in the prior art completely fills the tire with the function of completely replacing air and thus simulating pressures that ensure tire support. The wear of these inserts is early and is caused by the heat which is created between the ground and the tire and also by the internal rubbing which occurs between the insert, the rim, and the tire.

Therefore, the type of inserts of the prior art is not reliable over time to support the tire in the event of a puncture and also compromises the ideal dynamic performance of the tire during normal operation. Indeed, since this type of insert is in contact with the tire, it biases the dynamics of the tire and the wheel as a whole, thus not allowing for adequate standardization of performance and compliance with the necessary type-approvals for road vehicles.

It is the object of the present invention to overcome the aforesaid drawbacks of the prior art and to provide a tire insert which is capable of being reliable even under various conditions, temperatures, and stresses of use, while at the same time minimally affecting the dynamics of the entire tire-rim assembly when the insert itself is not required to work.

Furthermore, it is a further object of the present invention to allow, in the event of a puncture, to travel stretches of road at reduced speed, necessary for securing the vehicle or repairing the tire, without losing control of the vehicle itself and without damaging the rim of the vehicle/motorcycle.

Said purposes are achieved with a tire insert and a vehicle wheel according to the appended independent claims.

The dependent claims describe preferred or advantageous embodiments.

The features and advantages of the tire insert and the vehicle wheel will be apparent from the following description which illustrates some preferred embodiments, given by way of indicative, non-limiting examples, with reference to the accompanying figures, in which:.

With reference to the aforesaid figures, a tire insert for a vehicle wheel <NUM> suitable for being inserted in an inner annular cavity <NUM> which results between the tire <NUM> and a rim <NUM> of the vehicle wheel <NUM> is indicated by reference numeral <NUM> as a whole. The tire insert is also known in the industry by the term "foam or mousse".

Said tire insert <NUM> comprises an annular element <NUM> made in one piece and of polymeric material.

In an embodiment not encompassed in the scope of the present invention, the polymeric material is any material chosen from the group which comprises polyurethane, polystyrene, rubber, foam-rubber, open-cell or closed-cell foam, solid-skin foam.

According to the invention, said polymeric material is an expanded polymeric material.

The tire insert <NUM> is suitable for making at least partial contact with the rim <NUM> of the wheel <NUM>. Furthermore, the annular element <NUM> comprises a base portion <NUM>, suitable for being accommodated in a rim seat <NUM> of the wheel rim <NUM>, and an enlarged portion <NUM>, having a section larger than the base portion <NUM>. Said enlarged portion <NUM> comprises an outer enlarged portion surface <NUM> of convex shape and suitable for facing towards an inner tire side <NUM>. Preferably, the tire insert <NUM> has an entirely solid cross-section.

The enlarged portion <NUM> is shaped to have such shape and size that the enlarged portion <NUM> is always spaced apart from the inner tire side <NUM> when the tire is inflated to a predetermined standard working pressure. Furthermore, the shape and size of the enlarged portion <NUM> are such that, on the other hand, when the tire is deflated or when the tire has a pressure much less than the predetermined working pressure, the enlarged portion <NUM> comes into contact with the tire to support it while the wheel is running. This effectively allows the tire to be supported when it is punctured or there is a sharp pressure drop, and at the same time allows not to interfere with the performance of the tire when the tire is properly inflated because insert <NUM> is not in contact with and applies no pressure on it.

According to an embodiment, the enlarged portion <NUM> is shaped so that there is a space S between the outer enlarged portion surface <NUM> and the inner tire side <NUM>, having a decreasing course starting from the insert portion <NUM> farthest from the rim <NUM> to the insert portion <NUM> closest to the rim <NUM> when the tire is inflated to a predetermined standard working pressure. In other words, the volume of the space S interposed between the enlarged portion <NUM> and the inner side of the tire <NUM> decreases as a portion of said volume of the space S is considered closer to the rim <NUM>.

For example, in an embodiment, said feature is achieved by means of a shape of enlarged portion <NUM> comprising convex-shaped insert sidewalls <NUM> arranged facing the inner tire side <NUM> at the tire sidewalls <NUM> of the tire. In particular, said insert sidewalls <NUM> are shaped as a portion of a parabola or hyperbola.

According to an advantageous embodiment, the enlarged portion <NUM> has a bowl-shaped section, with a convex top edge <NUM> having convexity facing the inner side <NUM> of the tire. In this variant, the top edge <NUM> joins the insert sidewalls <NUM>, forming a totally convex enlarged portion section.

According to an embodiment, the base portion <NUM> is neck-shaped and comprises a lower base <NUM> suitable for resting against the rim <NUM> and an upper base <NUM> which is joined to the enlarged portion <NUM> and which is tapered relative to the lower base <NUM> i.e., has a smaller section.

According to a preferred embodiment, advantageous in the case of two-wheeled vehicles such as bicycles, the total radial height H of insert <NUM> is between <NUM> and <NUM>.

According to the present invention, the insert <NUM> is made entirely of an expanded polymeric material.

According to the present invention, the tire insert <NUM> is made entirely of ethylene vinyl acetate (EVA). Preferably, the ethylene vinyl acetate used has a density comprised between <NUM> and <NUM>/cm3, a breaking load comprised between <NUM> and <NUM>/cm2, an elongation at break comprised between <NUM> and <NUM>%, a tearing degree comprised between <NUM> and <NUM>/cm, a compression degree comprised between <NUM>% and <NUM>%, and a hardness either comprised between or equal to <NUM>-<NUM> Shore A, with the latter tending to change as the ambient temperature changes.

As appreciable from the accompanying figures, it is apparent that the present invention also addresses a vehicle wheel <NUM> comprising a tire <NUM>, a rim <NUM> on which tire <NUM> is mounted, and a tire insert <NUM> described in the present discussion. The tire <NUM> is to be understood as a typical tire having a tread <NUM> and an inner tire side <NUM> facing away from the tread <NUM>. The tire insert <NUM> is mounted in an inner annular cavity <NUM> which results between the inner tire side <NUM> and the rim <NUM>. The annular element <NUM> is positioned so that the base portion <NUM> is in contact with the rim <NUM> in the rim seat <NUM>. As described above, the enlarged portion <NUM> is shaped to have shape and size to be entirely spaced apart from the inner tire side <NUM> when the tire <NUM> is inflated to a predetermined standard working pressure of the tire. Furthermore, when the tire is deflated or when the tire is inflated to a pressure much less than the predetermined working pressure, the enlarged portion <NUM> is in contact with the tire <NUM> to support it during the movement of the wheel and to prevent the tire sidewalls <NUM> from wearing out.

As apparent from the accompanying figures, the tire insert <NUM> occupies less volume than the total volume of the resulting inner annular cavity <NUM> between the tire <NUM> and the rim <NUM>.

In particular, the tire insert <NUM> is shaped and sized so that it does not entirely occupy the volume of the inner annular cavity <NUM>.

Preferably, the tire insert <NUM> occupies a volume at most <NUM>% of the total volume of the resulting inner annular cavity <NUM> between the tire <NUM> and the rim <NUM>. More preferably, the tire insert <NUM> occupies a volume of at most <NUM>% of the total volume of the inner annular cavity <NUM>, even more preferably a volume of at most <NUM>% of the total volume of the inner annular cavity <NUM>.

As mentioned, advantageously between the outer enlarged portion surface <NUM> and the inner tire side <NUM> there is a space S, having a decreasing course starting from the insert portion <NUM> farthest from the rim <NUM> to the insert portion <NUM> closest to the rim <NUM> when the tire is inflated to a predetermined standard working pressure. This makes it possible to appropriately calibrate the gradual intervention of the insert on the tire as the tire inclination changes and as the internal pressure changes.

According to an embodiment, the base portion <NUM> is neck-shaped and comprises a lower base <NUM> resting against the rim <NUM> and an upper base <NUM> which is joined to the enlarged portion <NUM>. In this variant, the base portion <NUM> preferably also remains distanced from the tire inner side <NUM> at all times when the tire is inflated to a predetermined tire standard working pressure.

According to an embodiment, the inner diameter D of the tire insert <NUM>, when the insert is not mounted onto the rim <NUM>, has a shorter length than the inner rim diameter Dc, such that when the tire insert is mounted onto the rim <NUM> said insert applies a radial pressure to the rim seat <NUM> to stabilize the adhesion to the rim <NUM> itself.

Innovatively, the present invention brilliantly overcomes the mentioned drawbacks with regard to the tire inserts of the prior art.

The special shape and size of the enlarged portion, with convex sidewalls and top edge, reduce sidewall bulk and, most importantly, apply no pressure onto the sidewalls of the tire.

In this manner, the tire, free from sidewall contact, can work at its best. The vehicle ride is smoother and more precise when cornering while being unbiased by the presence of the insert, returning to the dynamic design performance of the wheel, under most driving conditions.

At the same time, advantageously, the insert and wheel according to the present invention are reliable over time to support the tire in the event of a puncture, because there is no fretting wear phenomenon between the insert and tire.

Therefore, the present invention is found to be extremely reliable and usable on most road vehicles, even if certain tire performance type-approvals are required.

It is apparent that the present invention is preferentially intended for tubeless wheels.

Claim 1:
A tire insert (<NUM>) for a vehicle wheel (<NUM>) suitable for being inserted into an inner annular cavity (<NUM>) which results between the tire (<NUM>) and a rim (<NUM>) of the vehicle wheel (<NUM>), said tire insert (<NUM>) comprising an annular element (<NUM>) made in one piece and of polymer material and suitable for coming at least partially into contact with the rim (<NUM>) of the wheel (<NUM>), wherein said annular element (<NUM>) comprises a base portion (<NUM>), suitable for being accommodated in a rim seat (<NUM>) of the wheel rim (<NUM>) and an enlarged portion (<NUM>), having a larger section than the base portion (<NUM>),
wherein said enlarged portion (<NUM>) comprises an outer enlarged portion surface (<NUM>) of convex shape and suitable for facing towards an inner tire side (<NUM>),
and wherein said enlarged portion (<NUM>) is shaped to have such shape and size that said enlarged portion (<NUM>) always remains spaced apart from the inner tire side (<NUM>) when the tire is inflated to a predetermined standard working pressure of the tire and such that, instead, when the tire is deflated or when the tire has a pressure much less than the predetermined working pressure, the enlarged portion (<NUM>) comes into contact with the tire to support it during the movement of the wheel,
said tire insert (<NUM>) being characterized in that it is entirely made of expanded ethylene vinyl acetate (EVA).