Elastic Vehicle Tire

The invention relates to an elastic vehicle tire comprising a tire cavity which is enclosed by a running strip supporting the tread surface and a side wall formed on each side of the running strip and having at least one noise dampening insert arranged in the tire cavity or one noise dampening insert arrangement arranged in the tire cavity.

Such vehicle tires are used in motor vehicles, trailers and semitrailers, and they are also referred to as vehicle pneumatic tires. These tires are cushion tires whose stability is achieved primarily by air pressure introduced into the cavity. The cavity of such a vehicle tire is formed by a running strip supporting the tread surface. The side walls abut against said running strip on both sides. The side walls each support, at their free end, a bead by means of which the tire mounted on a wheel rim rests against the rim well as well as the rim edge. In the case of tubeless tires, the bead rests sealingly against the rim edge or the rim well, so that the cavity formed by the vehicle tire is closed off by the rim.

When rolling the tread surface of such a tire on a paved road surface, rolling noises are generated particularly by the tire tread pattern produced in the tread surface. The resonance oscillations that are responsible for the rolling noises are conveyed as air-borne sound to the environment and as solid-borne sound through the wheel, the vehicle wheel suspension and the car body to the interior of the vehicle. In order to reduce the rolling noise, and particularly the resonance oscillations, vehicle tires have been developed which present an insert or a corresponding insert arrangement for noise dampening. Such a noise dampening insert is typically arranged on the inner side of the running strip. In part, the inserts also still extend at least partially along the side walls. As noise dampening insert, one typically uses foam inserts that are introduced into the tire cavity. As described in DE 30 42 350 A1, they are connected to the inner side of the tire, for example, glued to the latter, or attached by vulcanization to the latter. In DE 20 2008 009 008 U1, a such a vehicle tire configured with such noise dampening is described, in which a viscoelastic foam insert is provided as noise dampening insert.

Although it is sensible to use noise damped vehicle tires, particularly for reasons pertaining to environmental compatibility, these tires have not yet experienced a widespread introduction on the market. The reasons for this include that the tires heat up during rolling, particularly when taking curves. Even though a certain amount of heating of the running strip with its tread surface is advantageous in order to increase the adhesion to a paved road surface, its wear increases with increased heating of the tire. However, in the case of noise damped tires, heating of the running strip above an acceptable heating value often occurs. Consequently, the wear of such a tire is increased in comparison to a tire without noise dampening. It is assumed that the reason for stronger heating in noise damped tires is that the noise dampening foam insert, which is arranged on the inner side of the running strip, acts as a thermal insulator which prevents the radiation of heat into the internal space of the tire, if such radiation is possible at all. In order to counter this disadvantage of noise damped vehicle tires, it has been proposed to incorporate heat conducting particles in the foam insert, by means of which a heat conducting path is made available, from the inner wall of the tire through the noise dampening insert to the tire cavity, as described in JP 2005-104314 A and JP 2007-230544 A, for example. In contrast, in DE 20 2008 009 008 U1, it is proposed to incorporate microencapsulated phase transition material as latent heat storage material in the foam insert, in order to postpone the time when the tire reaches its still admissible peak temperature. In this conception, heat is consumed by the phase transition of this material. In this manner, temperature peaks during driving operation can be buffered with regard to tire heating.

These described solutions for removing heat from the inner side of the running strip of the tire have the disadvantage that additional material has to be incorporated in the foam, which results, however, in an increase of the weight of the noise dampening foam insert. Moreover, during the manufacture of the foam insert, one must ensure that the incorporated particles are in an arrangement such that the desired heat removal from the inner side of the running strip occurs as intended. Consequently, the particles used to form the desired heat removal paths have to abut against each other throughout the noise dampening layer. It has been found that the manufacture of foams with such incorporated particles is not unproblematic.

Proceeding from the discussed prior art, the invention is therefore based on the problem of further developing a noise damped vehicle tire of the type mentioned in the introduction and in accordance with the preamble in such a manner that an effective heat removal from the inner side of the running strip is possible, while avoiding or minimizing the indicated disadvantages of the prior art.

This problem is solved according to the invention by a vehicle wheel according to the preamble of claim 1, in which, between the noise dampening insert or the noise dampening insert arrangement, connected to the inner side of the running strip supporting the tread surface, a ventilation layer is arranged, which extends in the peripheral direction of the running strip and has a structure through which air can flow at least in the transverse and/or longitudinal direction of the running strip, and which is arranged to allow the passage of an air flow which is at least partially in contact with the inner wall of the running strip.

In the case of this vehicle tire, a ventilation layer, which is connected to the inner side of the running strip and has at least some transverse extent, is arranged in the radial direction between the inner side of the running strip and a noise dampening insert. Due to the ventilation layer, a path through which air can flow is created, so that the inner side of the running strip is air cooled, at least in the area of the extent of the ventilation layer. For this purpose, the ventilation layer extends in the peripheral direction of the running strip. It can be provided that the ventilation layer extends continuously over the entire periphery of the inner side of the running strip. It is equally possible to divide the inner peripheral surface of the running strip into individual ventilation layer segments, so that a noise dampening insert arrangement is formed in this manner. The ventilation layer is designed so that an air flow flowing through the former can absorb heat and remove it from said inner wall into the tire cavity. For this purpose, the air flow can absorb heat directly from the inner side of the running strip—that is to say from the rubber surface—or, as provided according to an additional embodiment, from a thermally conducting layer which is in contact with the inner side of the running strip, a metal foil, for example. In order to generate a heat removing air flow through the ventilation layer, the latter is connected in an appropriate manner to the inner side of the running strip of the wheel. Thus, the concept of connectedness subsumes all embodiments by means of which this state is achieved. Connectedness of the ventilation layer to the inner side of the running strip can be achieved, for example, by the application of the ventilation layer to the inner side of the running strip. It is equally possible to use a partial bracing of said layer on the inner side of the running strip. It is also possible to connect the ventilation layer by adhesion to the inner side of the running strip. As already indicated, the above-mentioned connection possibilities merely represent some embodiment examples.

According to an additional embodiment, it is provided that the ventilation layer is segmented just like the noise dampening layer, and the individual elements are arranged with a separation from each other. In this manner, an exchange between the air moved in the ventilation layers and the air present in the tire interior is possible. The purpose of this is the thermal control of the running strip, because in this manner the inner side of the running strip is cooled.

For the generation of the air flow provided for cooling the inner side of the running strip, the deformation of the tire while rolling on a substrate is used. The tire deformation while the tire is rolling on the substrate, during which deformation the running strip is successively pressed inward peripherally, and after leaving the substrate or being lifted from the latter, it is deformed back to its original position, is used in connection with the present air cooling, in order to generate an air flow that flows through the ventilation layer. The tire deformation is used in the manner of a peristaltic pump. Depending on the design and the geometry of the ventilation layer and the noise dampening insert, the air flow in the ventilation layer is generated directly by the above-described tire deformation during rolling, or such an air flow is generated in the remaining tire cavity which itself is in a connection with the ventilation layer that allows air flow. A combination of the two above-described basic air flow generation mechanisms is also possible. If air flow generation is desired directly in the ventilation layer, the latter typically has elastic properties. According to the other principle, the peristaltism of the tire generates the air flow in the remaining cavity, which flows into the ventilation layer, due to availability of the described paths. In order to successively elastically deform the ventilation layer by rolling the tire in the above-described manner, and as a result trigger a pumping effect in the ventilation layer, the ventilation layer is connected to the inner side of the running strip. Then, a deformation of the running strip can be transferred to the ventilation layer.

The ventilation layer can be connected directly to the inner side of the running strip. It is also possible to provide a thermally conducting layer, for example, a metal meshwork, which is attached to the inner side of the running strip. It is entirely possible to maintain the thermally conducting layer, if it comprises openings, applied against the tire inner side by the ventilation layer.

Thus, the ventilation layer is arranged on the thermally conducting layer. By means of such a thermally conducting layer, the cooling effect can be strengthened, because as a result of said layer, heat removal from the inner side of the running strip in the direction of the side walls, and preferably also along the inner sides of the side walls, can occur. Typically, such a heat conducting layer opens into a remaining tire cavity into which the heat is radiated. As material to form such a heat conducting layer, a material is used that conducts heat well. Here, a metal meshwork or a perforated metal foil can be used. It is also conceivable to use a continuous metal foil.

The thermally conducting layer can also be used for tethering or connecting the ventilation layer to the inner side of the tire. This succeeds if the thermally conducting layer is connected to the tire inner side, on the one hand, and to the ventilation layer, on the other hand, for example, using an adhesive, an adhesive layer, or by a vulcanization process. A rubber strip of required width with a thermally conducting core is suitable for this purpose, for example. This core can be configured as a meshwork, a nonwoven, a foil or the like with thermally conducting properties. It is also possible for the core to be formed by thermally conducting particles that are embedded in a matrix.

In the above described concept of air cooling of the inner side of the running strip or of at least a portion thereof, heat is removed effectively from the inner surface by the air flow that flows past. Air cooling is particularly effective if the ventilation layer is in a connection with the remaining cavity of the tire that allows air flow, so that an exchange of air occurs, and in association an exchange of heat by way of the mixing of the air flows. The ventilation layer can be in connection with the remaining cavity of the tire, for example, in that said layer itself delimits the remaining cavity with its lateral surfaces, for example. It is also possible for the noise dampening insert itself not to come in contact with the inner wall of the running strip and/or side walls, and thus to be held inside the ventilation layer. However, depending on the design of the ventilation layer and the noise dampening, it can be appropriate to brace the noise dampening insert in some sections against the inner side of the tire. It is also possible to use designs in which the noise dampening insert has perforations through which air can flow.

The above explanations clarify that the ventilation layer is a layer through which air flow can flow, and which separates the noise dampening insert at least largely from the inner wall of the tire. The above-described air cooling and the associated capacity to allow air to flow through, in the construction of the tire interior between the inner side of the tire and the noise dampening insert, has in addition the advantage that, for the first time, the side of the noise dampening insert that faces the inner side of the running strip is also used for the purpose of noise dampening. Consequently, this also produces a not inconsiderable increase in the surface area of the utilized noise dampening insert that is effective for the purpose of noise dampening. As a result, in this vehicle tire, not only its thermal properties but also its noise dampening properties are improved. Consequently, in order to achieve an equal noise dampening effect in a vehicle tire with a ventilation layer as described above, the noise dampening insert can be designed to be smaller, and thus be of lower weight.

Due to the application of the ventilation layer on the inner side of the running strip supporting the tire tread, the heat releasing surface of the inner side of the running strip can be increased to a not inconsiderable extent, if the material used for the construction of the ventilation layer at least partially exhibits good heat-conducting properties. In that case, the material used to construct the ventilation layer acts at least partially in the manner of a cooling body that is applied to the heat releasing inner side of the running strip, which has the consequence that the heat to be released is released over a larger surface area to the air flow that flows past.

An example of a material that is a good heat conductor is a layer produced from metal fibers, for example, a metal fiber nonwoven or a metal mesh. According to another embodiment, it is provided to produce the ventilation layer from an open pore material, wherein the pore cavity is sufficiently large for the purpose of allowing the passage of the desired air flow. Such an open pore layer as ventilation layer can be produced, for example, using a plastic and/or metal honeycomb structure, so-called hump profile structure mats or the like. In a preferred embodiment example, an open pore foam, particularly an open pore polyurethane foam, is used as open pore material. Reticular foams can also be used, produced as a reticular polyurethane foam, for example. Particles that are good heat conductors, for example, the already mentioned metal fibers, can be incorporated in such a foam. If the noise dampening insert is a foam body, it could be possible to produce the ventilation layer from a foam as well, since the layer can then be produced from one and the same base material. The above-described thermally conducting design of the ventilation layer can also be combined with a thermally conducting layer arranged on the inner side of the running strip, as already described above.

In connection with these designs, it must be understood that the ventilation layer has substantially no noise dampening properties and that air can substantially not flow through the noise dampening insert. The notion that air throughflow is substantially not possible means that the noise dampening insert, if it has an open pore design, cannot be referred to as impermeable to air, but that this air permeability is nonetheless not sufficient to meet the requirements for air flow that is provided in order to cool the inner side of the running strip.

The ventilation layer extends preferably peripherally along the inner side of the running strip. Here, one or more mutually parallel ventilation layers are used. They can have a straight or also a meandering course.

The ventilation layer which is the subject matter of the present invention thus is a layer through which a path allowing air to flow through is generated between a noise dampening insert and the inner side of the tire. It is provided that the air flow flows at least partially along the inner side of the running strip of the vehicle tire. A ventilation layer is considered suitable if it has an air permeability that is preferably greater than 500 L/min over a cross-sectional area of 1 dm², measured according to EN/ISO 9237. It is preferable to use ventilation layers that have an air through-flow capacity of more than 1000 L/min over a cross-sectional area of 1 dm². It is understood that higher air permeabilities are preferred. When using a ventilation layer formed by a reticular foam, values of 5000 L/min or more over a cross-sectional area of 1 dm²can also be achieved. The above-mentioned measurements are carried out on samples having a thickness of 1 cm.

The thickness of the ventilation layer also has an effect on the effectiveness of the air flow generated for the purposes of cooling the inner side of the running strip of the tire. The thickness of the ventilation layer is also a function of the geometry and of the size of the tire. The required thickness for such a ventilation layer is also influenced by the air permeability of the ventilation layer. This means that a ventilation layer having a higher air permeability can in principle have a smaller thickness than such a layer with lower air permeability. Taking into consideration these specifications, ventilation layers having thicknesses of 0.5 cm can be formed. However, the thickness of such a ventilation layer typically is 1.5-3 cm. In tests, satisfactory results have been achieved with ventilation layers having a thickness of 2 cm and an air permeability of 3000-4000 L/min over a cross-sectional area of 1 dm².

To further improve the cooling of the inner side of the running strip, it is possible to provide that the ventilation layer and/or the noise dampening insert or the noise dampening insert arrangement is/are provided with means that cause turbulent flow of the air conveyed through the ventilation layer. For example, one can use extensions here on the side faces of the ventilation layer and/or on the noise dampening insert. Openings (perforations) produced in the insert and/or the ventilation layer, typically by punching out, can also be used for this purpose. At the same time, due to the described measures, the surface area of the insert is increased, which improves the noise dampening.

Investigations on tires without noise dampening insert, tires with such an insert, and tires according to this invention have shown that, in tires with the ventilation layer according to the invention between the inner side of the running strip and the noise dampening insert, it is not possible to completely prevent a stronger heating than in tires that have no noise dampening insert at all. However, this heating is moderate in comparison to the heating of tires with a noise dampening insert but without ventilation. In tires according to the invention, a heating of only 50% or less was observed, in comparison to the heating of a tire having the same noise dampening insert but no ventilation layer.

Additional advantages and embodiments of the invention can be obtained from the following description of embodiment examples in reference to the appended figures.

FIG. 1 shows a diagrammatic cross section through a vehicle tire with a noise dampening insert and a ventilation layer according to a first embodiment, and mounted on the rim of a wheel,

FIGS. 2
a-2c show basic representations of additional embodiment examples of a noise damped vehicle tire provided with a ventilation layer,

FIGS. 3
a,
3
b show basic representations of a noise damped vehicle tire provided with a ventilation layer, in a longitudinal cross section of its respective lower section,

FIG. 4 shows a representation corresponding to that of FIGS. 3a, 3b, with an additional embodiment of a noise dampening insert and of a ventilation layer,

FIG. 5 shows a representation according to that of FIG. 4, with an additional embodiment of a ventilation layer with a noise dampening insert arranged thereon,

FIGS. 5
a,
5
b show additional embodiments of a ventilation layer with a respective noise dampening insert arranged thereon with respect to the embodiment of FIG. 5,

FIGS. 6, 6a, 6b show additional embodiments of a ventilation layer with a respective noise dampening insert arranged thereon, in a cross-sectional representation corresponding to that of FIG. 5 (FIG. 6) as well as in a top view on the inner side of the running strip (FIG. 6a) and in a variant (FIG. 6b),

FIGS. 7
a,
7
b show an insert for an elastic vehicle tire, comprising a noise dampening layer as well as ventilation layers introduced therein,

FIGS. 8
a-8g show basic representations of different units, each formed by a ventilation layer and a noise dampening insert in diagrammatic partial cross sections through a vehicle tire, and

FIG. 9 shows a partial longitudinal section through a vehicle tire with a unit inserted therein, consisting of a ventilation layer and a noise dampening insert.

A vehicle tire 1 made of rubber or of a rubber mixture comprises a running strip 2 whose outer side forms the tire tread 3 of the vehicle tire 1. Two side walls 4, 4.1 are formed on the running strip 2. Each of the side walls 4, 4.1 supports a bead 5, 5.1 on its end. For the sake of simplicity, the vehicle tire 1 is shown without reinforcement and without carcass. Similarly, the bead core typically contained in the beads 5, 5.1 is not represented. The vehicle tire 1, as shown in FIG. 1, is mounted on the rim 6 of a wheel 7. The beads 5, 5.1 are applied against the rim well, and they are pushed by the tire inner pressure with their beads 5, 5.1 against the respective abutting rim edge 8, 8.1.

In the vehicle tire 1, a viscoelastic foam insert marked overall with reference numeral 9 is arranged. The foam insert 9 is adhesively connected to the inner side 10 of the vehicle tire 1 at those sites where the foam insert 9 is applied directly on the inner side 10 of the tire 1. During a rotation of the vehicle tire 1, the foam insert 9 which is connected to the vehicle tire 1 thus also rotates. The foam insert 9 fills approximately 30% of the cavity 11 of the vehicle tire 1, cavity which is formed by the running strip 2 and the side walls 4, 4.1. In the represented embodiment example, the foam insert 9 follows the inner contour of the vehicle tire 1, wherein it is provided that the thickness of the foam insert 9 is greater in the area of the running strip 2 than in the abutting side wall sections 12, 12.1 in which the foam insert 9 thins out in the direction of the beads 5, 5.1. With their surface delimiting the cavity 11, the side wall sections 12, 12.1 extend at least partially parallel to, or at a slight angle of inclination with respect to, the inner surface of the vehicle tire 1.

The foam insert 9 is used to damp the resonances of the enclosed volume of air, in combination with a high dampening capacity, particularly in a frequency range below 400 Hz, and particularly in a frequency range between 200 and 250 Hz. The depicted geometry of the foam insert 9, with its base section and the side wall sections 12, 12.1, clearly shows that an oscillation dampening of the elastic vehicle tire 1 occurs not only in the area of the running strip 2, but also in the area of the side walls 4, 4.1. Overall, the foam insert 9 thus has a U-shaped design.

Due to the foam insert 9, the tire cavity originally available in the vehicle tire 1 is reduced. Therefore, in the context of these explanations, the tire cavity 11 that remains is also referred to as remaining tire cavity.

A ventilation layer 13 is enclosed by the noise dampening foam insert 9. The ventilation layer 13 is located between the inner side 10 of the running strip 2 and the foam insert 9. In the represented embodiment example, the ventilation layer 13 is designed as an open pore foam portion, enabling an air flow in it, which flows at least partially past the inner side 10 of the running strip 12. The ventilation layer 13 has no appreciable noise dampening properties. On the other hand, there is almost no air flow or at least not enough air flow through the foam insert 9. The ventilation layer 13 is used to remove heat from the inner side 10 of the running strip 2 during the rolling process of the tire 1. The elastic work of the vehicle tire 1 is exploited, as is the fact that the heat production is a consequence of the deformation work generated while rolling on a substrate and the associated deformation, while the tire 1 is air cooled in its remaining sections, also as a result of the rotation. For example, mutually offset perforations 14 are advantageously produced in the foam insert 9, in order to allow an exchange of air flow between the air located in the cavity 11 of the tire 1 and the air flow generated in the ventilation layer 13. As a result, the removal of heat from the inner side 10 of the running strip 2 in order to cool the latter is improved, in comparison to a design without perforations. For this purpose, the perforations 14 have a sufficiently large cross section to allow throughflow. At the same time, the number of the perforations 14 is sufficiently large to allow air circulation between the cavity 11 and the ventilation layer 13. For this purpose, air can flow through the ventilation layer 13 equally in all directions.

The introduction of perforations into the ventilation layer 13 in addition increases the usable surface area of the foam insert 9 for the desired dampening purposes, since the lateral areas of the perforations 14 are noise or resonance dampening.

In FIGS. 2a-2c, additional embodiment examples of various arrangements of noise dampening inserts and ventilation layers are shown diagrammatically. In the embodiment example of FIG. 2a, the ventilation layer 15 with its lateral closing-off portion extends to the lateral closing-off portion of the noise dampening insert 16. In this design, the remaining cavity of the vehicle tire R is also delimited by portions of the ventilation layer 15. Consequently, the latter is in direct air exchange with the tire cavity.

The situation is the same in the embodiment example of FIG. 2b. In this example, the ventilation layer 17 extends laterally around the noise dampening insert 18.

In the embodiment example of FIG. 2c, the noise dampening insert 19 as a whole is accommodated in a ventilation layer 20. In this embodiment example, the entire cavity of the tire R is substantially filled with the material of the ventilation layer 20. In a design in which the noise dampening insert is supported by the materials forming the ventilation layer, or the noise dampening insert is enclosed in the ventilation layer, wherein the ventilation layer extends at least over the entire width of the tire cavity, this unit formed by the ventilation layer and the noise dampening insert can be held in a form-fitting and/or force-fitting connection inside the tire. In such a design, this unit does not have to be glued to the inner side of the tire. The desired connection with the inner side of the tire is achieved advantageously in that the unit is designed so that its width relative to the width of the inner space of the tire is broader, and it is thus held in this direction under a certain preliminary stress in the standing position between the side walls of the tire. Due to this force-fitting connection, a rotational entrainment of the material of the ventilation layer and thus also of the dampening insert is ensured. Since, in such a design, one can dispense with the use of an adhesive layer between the inner side of the vehicle tire and the ventilation layer, the cooling effect is improved correspondingly. Alternatively, or also complementarily to this, a force-fitting application of the unit formed by the ventilation layer or ventilation material and the noise dampening insert in the radial direction can exist as well.

In principle, various materials are suitable for different designs of a ventilation layer, as long as it is ensured that a sufficient air flow for the desired heat removal can flow through it. In the described embodiment examples, the ventilation layer is produced from an open pore reticular polyurethane foam. The latter in the end is used only as supporting body to keep open a path through which air can flow on the inner side 10 of the running strip 2.

For the generation of the already previously described air-cooling air flow on the inner side 10 of the running strip 2, the deformation of the tire R during rolling is used in each case, as shown using the basic representations of FIGS. 3a and 3b. FIG. 3a shows a design in which the ventilation layer 21 through which air can flow can be deformed more easily than the noise dampening insert applied to it on the inner side. Due to the deformation of the tire R in the area of its footprint A formed in the peripheral direction depending of the speed of rotation, the ventilation layer 21 is pushed in peripherally, and thus there is a reduction in terms of its cross-sectional area that allows free throughflow. Due to the rotation of the tire R, an air flow is generated in this manner within the ventilation layer 21, in particular based on the principle of a peristaltic pump. Due to the air flow, the heat that is generated in the area of the respective deformation of the ventilation layer 21 is removed immediately, in particular to cooler areas of the tire, or, in the case where the noise dampening insert 22 has perforations, or the ventilation layer 21 is open in the direction transverse to the rotation direction, air exchange occurs and accordingly heat removal with the air contained in the tire interior. Thus, due to the peripheral deformation of the ventilation layer 21 in the case of a rotation of the tire R, the heat is removed immediately after its generation, by the air flow on the inner side 10 of the running strip 2 in the area of the deformation by the developing air flow. Excessive heating due to heat accumulation is thus effectively prevented.

FIG. 3
b shows a ventilation layer 23 which, relative to the noise dampening insert 24 abutting against it, is pressed inward together with said layer during the rolling process of the tire R. In this embodiment example as well, an air flow is generated within the tire R according to the principles of a peristaltic pump. In this embodiment example, the ventilation layer 23 is in a flow exchange with the air contained in the tire interior, so that air also flows in this manner through the ventilation layer 23.

FIG. 4 shows an additional embodiment example, in which a noise dampening insert arrangement 25 is arranged on a continuous ventilation layer 26. In this design, the noise dampening insert arrangement is formed by a plurality of individual noise dampening inserts, which are all mutually separated. In this manner, an air flow within the ventilation layer 26, and, due to the separation between the individual noise dampening inserts, also through the area between said inserts and into the remaining tire cavity is possible. In the represented embodiment example, the noise dampening inserts have a rectangular design. They can also have other geometric cross sections, for example, triangular, or the cross section of a quarter of a circle. In the design of FIG. 4, the noise dampening inserts can be impermeable to air. It is also possible to use a design in which the noise dampening inserts of the noise dampening insert arrangement 25, which are set on the ventilation layer 26, are also permeable to air, particularly also to a reduced extent compared to the ventilation layer 26.

FIG. 5 shows an additional embodiment example, in which not only the noise dampening insert, but also the ventilation layer is segmented. The noise dampening insert is marked with the reference numeral 27 in this embodiment example. The ventilation layer bears the reference numeral 28. The geometric arrangement of the individual segments shown in FIG. 5, each consisting of a section of the ventilation layer 28 and a section of a noise dampening insert 27, is an example. In this regard as well, the mutually separated segments can have different cross-sectional shapes, and they can also be arranged with a different separation from each other. Examples of this are shown in FIGS. 5a and 5b. Here, the tire is marked with the reference numeral R, the ventilation layer with V, and the noise dampening insert with S.

FIG. 6 shows an additional embodiment example of a ventilation layer V which is inserted in an elastic tire R and connected to the inner side of its tire tread, and which has a noise dampening insert S arranged thereon. The body formed by the ventilation layer V and the noise dampening insert S is perforated by openings P produced therein, in particular up to the inner side of the running strip of the tire. In the represented embodiment example, the openings have a cross-sectional area that remains the same. In the top view of FIG. 6a, showing the top side of the noise dampening insert S, which faces the cavity of the tire R, one can see that the openings have a circular cross-sectional geometry. Alternative cross-sectional geometries are also possible, such as a square cross-sectional geometry, as shown in FIG. 6b, for example.

In the embodiment example shown in FIG. 6, the openings P have been produced in mutual alignment through the noise dampening insert S and through the ventilation layer V, typically using a stamping process. According to another embodiment, the openings of the noise dampening insert can also be arranged with offset relative to those of the ventilation layer, even to the extent that the openings in the ventilation layer are covered completely by a section of the noise dampening insert, and thus are not in direct connection with the tire cavity. Then, the ventilation layer and the noise dampening insert are perforated independently of each other before their connection.

Yet another embodiment example of an arrangement, consisting of a noise dampening insert 29 and a ventilation layer 30, is shown in FIGS. 7a, 7b. FIG. 7a shows a top view of the inner surface area of the noise dampening insert 29. The arrangement of several ventilation layers with strip-like design is marked with broken lines and arrows, wherein the layers extend diagonally to the rotation direction which corresponds to the longitudinal extent of the noise dampening insert 29. FIG. 7b shows a cross section along line C-C of FIG. 7a.

The embodiment example of FIGS. 7a, 7b shows that a certain amount of bracing of the noise dampening insert on the inner side of the running strip of a vehicle tire is certainly possible. In the embodiment example of FIG. 7a, 7b, the brace is in the shape of a ledge. However, if desired, this brace can also be provided as an islet-shaped brace in the form of columns or individual ledges.

In FIGS. 8a-8g, various arrangements of a unit inserted in an elastic vehicle tire R are shown, each consisting of a ventilation layer V and a noise dampening layer S. The air flows which are generated during the rolling of the tire on a substrate are drawn with broken lines. Due to the sectional position, only air flows generated transversely to the rotation direction of the tire R, or their flow components, can be seen. In all the embodiment examples of FIG. 8 shown, an air flow develops additionally in the peripheral direction of the tire R.

In FIG. 8a, the ventilation layer V has the same width as the noise dampening insert S. This unit is less broad than the inner width provided by the tires R. For this reason, the lateral surfaces which can be seen in FIG. 8a delimit the tire cavity, so that the transverse air flows shown in FIG. 8a can be generated.

FIG. 8
b corresponds substantially to the embodiment example already shown in FIG. 1.

FIG. 8
c is an asymmetrical arrangement of a unit formed by ventilation layer V and a noise dampening insert S. The arrangement is asymmetric, because it is arranged eccentrically relative to the center longitudinal plane of the tire R. As drawn in FIG. 8c, an air flow cylinder can be formed in such a design.

In FIG. 8d, the ventilation layer V of the unit inserted in the tire R is designed with an asymmetric thickness. The thickness of the ventilation layer is greater on one of its sides (on the right in the figure) than on its other side (on the left in the figure). The thickness of the noise dampening insert S shown in the embodiment example is complementarily to this, so that the unit formed by the ventilation unit V and the noise dampening insert S overall has a rectangular cross section. Due to this design of the ventilation layer V formed, a transverse flow directed in one direction (here to the right) typically forms. In contrast to this, in the embodiment example of FIG. 8a, a transverse air flow or a transverse air flow component develops in both directions, i.e., to the left and to the right in the figure.

FIG. 8
e shows an additional embodiment, which is similar with respect to air flow generation to that of FIG. 8a. The ventilation layer V of this embodiment example is taper cut toward the center, and it increases from the center in the direction of the two lateral closing-off parts.

FIG. 8
f shows yet another embodiment corresponding basically to that of FIG. 8a. In this embodiment example, the ventilation layer V is broader than the noise dampening insert S. The noise dampening insert S in this embodiment example is located at the center of the ventilation layer V. In a variant of such a general embodiment example, it is possible to provide that the ventilation layer V has, above its periphery, transversely to the turning direction of the tire, viewed in the rotation direction of the tire, protrusions by means of which turbulences are introduced in the generated air flow. In the represented embodiment example, the protrusions are designed as bent extensions, wherein the bending is directed against the flow direction of the air in the tire interior. Causing turbulent air flow in the tire interior promotes heat removal from the inner side of the running strip into the interior of the tire.

FIG. 8
g shows an embodiment example which is similar to that of FIG. 8f. In the embodiment example of FIG. 8g, the ventilation layer V has a smaller width than the noise dampening insert 2. The ventilation layer V in this embodiment example is arranged at the center relative to the inner side of the running strip and relative to the noise dampening insert S. The noise dampening insert S in the embodiment example of FIG. 8g has a geometry as described for the ventilation layer V in the embodiment example of FIG. 8f. In this design, in addition to the generation of turbulence in the air flow flowing in the tire interior, the surface of the noise dampening insert S is enlarged, and consequently the noise dampening effect is improved further.

Yet another embodiment example of a unit inserted in a vehicle tire R, consisting of a ventilation layer V and a noise dampening insert S, is shown in FIG. 9. In this design, the noise dampening insert S has a wavy structure pointing in the direction of the inner side of the tire R. This structure is filled by a corresponding complementarily wavy structure on the ventilation layer V. By means of a structure of the noise dampening insert S that is designed in this manner, the effective surface for the purposes of noise dampening of the insert is considerably increased, and consequently the noise dampening effect is improved.

In all the described embodiment examples, the peristaltic pump activity of the tire due to its deformation during the rolling process is responsible for the generation of the air flow, which is skillfully used for generating the air stream provided in order to cool the inner side of the vehicle tire.

The ventilation layers used in the above-described embodiment examples are layers made of a reticulated polyurethane foam. Such foams are first of all bodies produced as open pore foams having a skeleton that consists of relatively stable fibers, which are connected by thin membranes, the so-called windows. The latter form the cell walls. The reticulation relates to the method used to remove or open these cell walls, and consequently increase the throughflow path. For this purpose, different chemical and thermal methods are known. They are described in U.S. Pat. No. 3,405,217, U.S. Pat. No. 3,423,338, U.S. Pat. No. 3,425,890 or U.S. Pat. No. 4,670,477, for example.

Numerous additional design possibilities for carrying out the invention, which do not need to be described in detail in the context of this explanation, are apparent to a person skilled in the art, without going beyond the scope of the claims. This relates, for example, to the combination of the individual characteristics of the invention, which are explained in relation to each embodiment example.

List of Reference Numerals

1 Vehicle tire

2 Running strip

3 Tire tread

4, 4.1 Side wall

5, 5.1 Bead

6 Rim

7 Wheel

8, 8.1 Rim edge

9 Foam insert

10 Inner side

11 Cavity

12, 12.1 Side wall section

13 Ventilation layer

14 Perforation

15 Ventilation layer

16 Noise dampening insert

17 Ventilation layer

18 Noise dampening insert

19 Noise dampening insert

20 Ventilation layer

21 Ventilation layer

22 Noise dampening insert

23 Ventilation layer

24 Noise dampening insert

25 Noise dampening insert arrangement

26 Ventilation layer

27 Noise dampening insert

28 Ventilation layer

29 Noise dampening insert

30 Ventilation layer

A Footprint

R Tire

P Opening (perforation)

S Noise dampening insert

V Ventilation layer

Elastic Vehicle Tire

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