WO2014096285A1

WO2014096285A1 - Structural device for reducing the road noise of a tyre

Info

Publication number: WO2014096285A1
Application number: PCT/EP2013/077535
Authority: WO
Inventors: Yu Shiraishi; Salvatore Pagano; Gael Roty
Original assignee: Compagnie Generale Des Etablissements Michelin; Michelin Recherche Et Technique S.A.
Priority date: 2012-12-20
Filing date: 2013-12-19
Publication date: 2014-06-26
Also published as: FR2999987A1

Abstract

Tyre (1) comprising a crown (2) surmounted radially on the outside by a tread (20) and extended on each side by lateral parts each comprising a sidewall (3) ending in a bead (4) designed to collaborate with a mounting rim of the tyre, each bead (4) comprising at least one circumferential reinforcement (6), this tyre comprising a carcass reinforcement (5) anchored at each of its two ends in a bead by being turned up around the circumferential reinforcement (6) to form a turn-up (51), this carcass reinforcement (5) extending into the sidewalls (3) and into the crown (2) of the tyre and being surmounted radially on the outside by a crown reinforcement (7), this tyre comprising in at least one of its lateral parts at least one cavity (8, 8', 8") in fluidic communication with the outside of the tyre, each cavity (8, 8', 8") having a volume suited to forming a Helmholtz resonator calibrated to attenuate the road noise of the tyre at least in part, this tyre being such that each cavity (8, 8', 8") that forms a Helmholtz resonator in at least one of the lateral parts of the tyre is arranged in the circumferential direction and filled with an open-cell cellular material.

Description

STRUCTURAL DEVICE FOR REDUCING THE TURNING NOISE OF A TIRE.

Field of the Invention [0001] The present invention relates to tires comprising in their structure a device for attenuating the noise generated by a tire while taxiing on the road.

Prior art

In many countries, regulations have been established to impose a significant reduction in noise generated by vehicles during taxi. This has led tire manufacturers to seek to reduce the amount of noise from the tires on these vehicles. Recently, a labeling system has been introduced on the tires in order to inform the consumer of the levels of performance and in particular of the noise level while taxiing.

[0003] A tire for a passenger vehicle generally comprises an extended vertex on either side of flanks terminating in beads intended to cooperate with a tire mounting rim. This tire once mounted on its mounting rim delimits an internal cavity which is subjected to an inflation pressure; this tire comprises a carcass reinforcement anchored at both ends in beads, this reinforcement extending in the sides and in the top of the tire. In addition, this carcass reinforcement is surmounted radially on the outside by a crown reinforcement usually composed of a plurality of reinforcing plies, this crown reinforcement itself being surmounted by a tread intended to come into contact with a road when using the tire.

It is known that a rolling tire generates noise comprising different components, among which we can distinguish external noise components and internal tire noise components. Among the noise components external to the tire, there is a resonance noise of the air circulating in the grooves of the tread during passage through the contact. There is also an external noise generated by vibrations of the air contained in the air wedge formed between the road and the tire in the front part of the tire. This resonance noise occurs for frequencies between 500 and 2000 Hz. Finally, there is a noise component in the external part of the tire on the side of its flanks. Among the components of internal noise, there is a noise, called "cavity noise" which is related to a resonance of the air contained under pressure in the internal cavity defined by the tire and its mounting rim. The resonant frequency of the air in the cavity is a function of the circumferential length of the tire. For example, a tire of dimension 205/55 R 16 has a resonance frequency located around 200 to 250 Hz. Various solutions have been proposed for reducing one or the other of these components.

The objective of the present invention is to further reduce the components of the internal and / or external rolling noise, in particular the external noise generated in the lateral parts by the tire. By side parts of a tire is meant in this document, the beads and flanks of a tire.

It is known to reduce the rolling noise to form in the tire structure at least one cavity of suitable size to play the role of a vibration absorber or that of a Helmholtz type resonator or that of a quarter-wave type resonator, each cavity being or not in fluid relation with the outside air surrounding the tire or with the internal cavity of the tire.

JP-A-2001071723 discloses a tire having a carcass reinforcement anchored in beads, each bead being intended to cooperate with a mounting rim. This mounting rim defining with the tire a cavity for containing the inflation pressure of the tire in use. Each bead comprises a circumferential reinforcing reinforcement around which is anchored by turning the carcass reinforcement. Between the carcass reinforcement and its upturn and radially outside the circumferential reinforcing armature there are a plurality of cavities filled with a fluid, these cavities being distributed in the circumferential direction and calibrated to act as absorbers. vibration generating noise during taxiing.

The patent application published under the number WO 2008/071422 also describes a tire comprising in its structure at least one tube connected by a fluid passage towards the interior of the tire cavity to reduce the resonance noises due to the vibrations of the air included in said cavity.

This type of solution, although satisfactory in terms of noise reduction in rolling, has a major disadvantage resulting from the substantial change in stiffness of the tire and consequently a reduction in its performance.

There are also solutions that do not alter the stiffness of the tire by having Helmholtz resonators or quarter wave on the tire mounting rim, such as in WO 2005/068223. This type of solution, however, has several disadvantages: the need to intervene on the mounting rim and the difficulty of mounting the tire on the rim. Moreover, this type of resonator does not reduce the running noises generated by the lateral parts of the tire with the surrounding air.

[0011] Definitions:

By radial direction is meant in this document a direction which is perpendicular to the axis of rotation of the tire (this direction corresponds to the direction of the thickness of the tread).

By transverse or axial direction means a direction parallel to the axis of rotation of the tire.

By circumferential direction is meant a direction which is tangent to any circle centered on the axis of rotation. This direction is perpendicular to both the axial direction and a radial direction.

By axially outwardly, we mean a direction which is oriented towards the outside of the internal cavity of the tire.

Equatorial plane: plane perpendicular to the axis of rotation and passing through the axially outermost points of the tire, this equatorial plane virtually dividing the tread of the tire into two halves of substantially equal widths.

The usual tire rolling conditions or conditions of use are those defined by the ETRTO standard; these conditions of use specify the reference inflation pressure corresponding to the load capacity of the indicated tire by its load index and its speed code. These conditions of use can also be called "nominal conditions" or "conditions of use".

Description of the invention

The object of the invention is to provide a solution for reducing the external and internal components of the rolling noise of a tire, and more particularly noise in the frequencies ranging from 500 Hz to 2000 Hz for noise. and frequencies in the range of 200 Hz to 250 Hz for internal noise, while maintaining the tire a level of rigidity suitable for obtaining good performance in taxi. For this purpose, the invention relates to a tire intended to be mounted on a mounting rim, the tire comprising an apex extended on either side by side portions each comprising a sidewall ending in a bead provided for cooperate with the tire mounting rim. Each bead comprises at least one circumferential reinforcing reinforcement. This tire comprises a carcass reinforcement anchored at each of its two ends in a bead by turning around the circumferential reinforcing reinforcement to form a reversal. This carcass reinforcement extends in the flanks and in the top of the tire. It is surmounted radially outward by a crown reinforcement.

This tire comprises in at least one of its lateral parts, at least one cavity in fluid connection with the outside of the tire, each cavity having a suitable volume to form a resonator type Helmholtz calibrated to attenuate at least part of the noise generated during taxiing. This tire is characterized in that each Helmholtz-type resonator cavity in at least one of the tire side portions is disposed in the circumferential direction and is filled with an open-cell cellular material.

By fluid connection with the outside of the tire means that each cavity, formed in the thickness of the tire, is open to ambient air surrounding the tire or the inner cavity of the tire. In the first case, the pressure which is established in each cavity is the atmospheric pressure whereas in the second case - opening on the internal cavity - it is the pressure of the internal cavity which is established. By Helmholtz resonator means here a calibrated cavity to attenuate a frequency, this cavity comprising a main volume communicating with the outside by a small tube ("neck" in English) of reduced section. An advantage of this type of resonator is to be relatively simple and easy to calibrate according to the sound frequencies that it is desired to reduce.

This arrangement allows attenuation of the amplitude or even the suppression of noise in a range of frequencies previously selected according to the desired result.

In a particularly interesting variant, the material used is a foam-type cellular material whose interest is to be both light and rigid enough to allow proper operation once incorporated into the tire structure.

This cellular foam-type cellular material is chosen from foams formed from metals having melting points of less than 2000 ° Celsius, such as tin, zinc, magnesium, aluminum, silver, nickel, and the like. copper, manganese, silicon, nickel, cobalt, iron, titanium, zirconium, vanadium.

Preferably, one chooses from metal foams based on magnesium, aluminum, copper, silicon, titanium, nickel, cobalt or iron. These materials have the advantage of providing in foam form mechanical properties suitable for the present application as a resonator filling material. Preferably the apparent density of the metal foam material material is at least 0.5 and at most equal to 1.8. This range of densities corresponds to the range of expansion - 400% to 600% - that can be achieved by the process of obtaining such foams (such a process is described in US Patent 4713277).

It has been observed that the size of the cells of the metal foam should preferably be between 1 μιη and 3 mm, and even more preferably between 5 μιη and 2 mm and even more preferably between 10 μιη and 1 mm. The size of a cell is defined as the largest dimension of said cell. If the size of the cells is less than 1 μιη, it is not certain that the resonator can still play its role of resonator, the cells can be closed. Above 3 mm, the mechanical strength of metal foams may become insufficient. In an advantageous variant, the tire according to the invention is characterized in that at least one cavity is formed in or near a bead, this cavity having a section seen in a section plane containing the axis of rotation of the tire which is elongated. This elongated shape is chosen from oval, rectangular or triangular shapes. This elongated shape in the radial direction is favorable to ensure proper mechanical operation of the beads during rolling given the repeated bending at each wheel revolution.

In another advantageous variant, and to further increase the bending flexibility at each wheel revolution, the tire according to the invention is characterized in that a plurality of cavities disjoined from each other is formed in the direction circumferentially, these cavities being filled with an open cell cellular material.

This arrangement has the advantage of facilitating the bending of the tire in the transverse direction. To further reduce the noise while driving, it is possible to combine in a tire comprising resonators in at least one of the side walls of the tire the presence of at least one resonator of the same type in the top of the tire. Each resonator in the apex is formed by at least one cavity in fluid connection with the atmosphere surrounding the tire when it is mounted on its rim, each cavity having a suitable volume to form a resonator calibrated to at least partially attenuate the noise in a pre-selected frequency range. Each cavity thus formed in the tire crown is arranged in the circumferential direction and is filled with an open cell cellular material. Preferably, these cavities are located radially under the part of the tread intended to be used in rolling so as not to come into contact with the roadway when driving.

These cavities formed in the top are like those formed in the side walls of the tire filled with a foam-type cellular material whose interest is to be both light and rigid enough to allow a smooth operation once. incorporated in the structure of the tire top. In an advantageous variant, the tire according to the invention is such that its tread comprises a plurality of grooves, at least one groove is oriented circumferentially, each groove being delimited by walls, these walls being interconnected by a groove bottom, and in that the cavities filled with an open-cell cellular material are formed radially inside the groove bottoms, each cavity being provided to open in at least one groove.

This arrangement has the advantage of facilitating the bending of the tire in the circumferential direction.

In another advantageous variant, and to further increase the flattening flexibility, the tire according to the invention is such that a plurality of cavities disjoined from each other in the circumferential direction, each cavity is formed. extending substantially from one edge to the other of the tread, these cavities filled with a cellular material opening in at least one groove.

In another advantageous variant, the tire according to the invention comprises a plurality of cavities disjoined from each other in the transverse direction, each cavity making a complete revolution of the tire and opening in at least one groove.

This arrangement has the advantage of facilitating the bending of the tire in the transverse direction.

In another advantageous variant, a better circumferential and transverse flexibility is combined by providing the tire according to the invention with a plurality of cavities disjoined from each other in the circumferential direction and in the transverse direction, these cavities being uniformly distributed. in the tire crown both in the circumferential direction and in the transverse direction, each cavity filled with a cellular material opening in at least one groove. Brief description of the drawings

Other features and advantages of the invention appear from the description given below with reference to the accompanying drawings which show, by way of non-limiting examples, embodiments of the object of the invention. [0041] Figure 1 shows a partial view of a tire according to a first variant of the invention;

[0042] Figure 2 shows a partial view of a tire according to a second variant of the invention; Figure 3 shows a meridian sectional view of a portion of a tire according to a third embodiment of the invention.

Detailed Description of the Invention

To facilitate the reading of the figures, the same reference signs can be used for the description of variants of the invention since these reference signs refer to elements of the same nature that it is structural or functional.

[0045] Figure 1 shows a partial view of a tire according to a first variant of the invention. According to this first variant, a tire comprises a carcass reinforcement

In this first variant, a tire 1 of size 205/55 R 16 comprises an apex 2 extended at its axial ends by flanks 3 ending in beads 4 provided to cooperate with a tire mounting rim. This tire 1 comprises a carcass reinforcement 5 anchored at its two ends in the beads 4 by circling a circumferential reinforcing reinforcement 6. This carcass reinforcement 5 extends in the sidewalls 3 and in the top 2 of the tire . The carcass reinforcement 5 is surmounted radially on the outside by a crown reinforcement 7 composed of two working plies 71, 72 whose reinforcements are crossed from one ply to the next, this crown reinforcement 7 being surmounted by a tread 20 intended to come into contact with the road during use of the tire.

In each bead 4, the carcass reinforcement is returned to form a turnaround 51. Between the upturn 51 and the carcass reinforcement 5, there is formed a cavity 8 continuous circumferentially. This cavity 8 extends radially beyond the radially outermost end of the upturn and has a profile seen in section which is curved in order to better follow the profile of the carcass reinforcement. This cavity ends radially on the inside near the reinforcing reinforcement of bead 6. The cavity 8 is in fluid communication with the internal cavity of the tire intended to contain the inflation pressure of the tire thanks to the presence, in the present case, of a plurality of orifices passing through the carcass reinforcement to form a Helmholtz resonator significantly reducing the noise generated by the vibrations of the inflation air. In a variant not shown, a single orifice may suffice.

In addition, the cavity 8 is filled with a nickel-based metal foam marketed under the name "Celmet4" by "Sumitomo Electric Industries Co". The average open cell size of the metal foam is 1 mm. The introduction of this metal foam is performed during the manufacturing phase of the tire in the blank state; the molding of the tire and its vulcanization solidarises the metal foam to the tire. The cavity filled with metal foam provides an effective noise reducing device while retaining the appropriate tire bead structure.

[0050] Figure 2 shows a partial view of a tire 1 according to a second embodiment of the invention. According to this second variant, a cavity 8 'forming a Helmholtz resonator is filled with metal foam and is formed on each side of the tire in order to reduce the noise generated laterally on the sidewalls by the bending movements that the said sidewalls undergo during rolling.

Each cavity 8 'is formed radially and axially outside the carcass reinforcement 5 and in a region extending axially outwardly from the crown reinforcement 7. This cavity 8' is filled with a metal foam with open cells and is open to the outside of the tire through a circumferential groove. This groove is not intended to come into contact with the roadway when driving.

Figure 3 shows a meridian sectional view of a portion of a tire according to a third embodiment of the invention.

In this third variant, the tire 1 comprises in its tread a plurality of main grooves 9 of generally circumferential orientation.

In addition, it is formed radially outside the crown reinforcement 7, a cavity 8 "extending over substantially the entire width of said crown reinforcement 7 and in the circumferential direction. 8 "cavity opens both axially on either side in each of the flanks 3 by grooves 82 "and also in the main grooves 9 of the tread.

Thus, thanks to the invention, it is possible to reduce both the resonance noise in the main grooves and in the air wedge at the front of the tire and the noise generated laterally to the tire between the sidewalls of the tire and the roadway.

Claims

Tire (1) comprising a crown (2) surmounted radially on the outside by a tread (20) and extended on either side by lateral portions each comprising a sidewall (3) terminating in a bead (4) adapted to cooperate with a tire mounting rim, each bead (4) comprising at least one circumferential reinforcing reinforcement (6), said tire comprising a carcass reinforcement (5) anchored at each of its two ends in a bead by turning around the circumferential reinforcement armature (6) to form a turn-up (51), said carcass reinforcement (5) extending in the sidewalls (3) and in the top (2) of the tire and being overcome radially outwardly by a crown reinforcement (7), this tire comprising in at least one of its lateral parts, at least one cavity (8, 8 ', 8 ") in fluid connection with the outside of the tire each cavity (8, 8 ', 8 ") having a volume suitable for forming a resonate of calibrated to at least partially attenuate the external noise in a frequency range between 500 and 2000 Hz or at least in part the noise internal to the tire in a frequency range from 200 to 250 Hz, this tire being characterized in each Helmholtz resonator cavity (8, 8 ', 8 ") in at least one of the tire side portions is disposed in the circumferential direction and is filled with an open-cell cellular material.

2- Tire according to claim 1 characterized in that at least one cavity (8) is formed in or near a bead (4), this cavity (8) having a section which is seen in a section plane containing the axis of rotation of the tire, elongate in the radial direction and selected from oval, rectangular or triangular shapes.

3- Tire according to claim 1 characterized in that at least one cavity (8 ') is formed radially and axially outside the carcass reinforcement (5) and in the vicinity of the axial end of the armature vertex (7), this cavity (8 ') opening in one of the flanks (3) by a circumferential orientation groove.

4- Tire according to one of claims 1 to 3 characterized in that it is formed a plurality cavities (8, 8 ', 8 ") disjoined from each other in the circumferential direction.

5- Tire according to claim 1 or claim 2 characterized in that at least one cavity (8) filled with foam opens inside the internal cavity of the tire for containing the inflation pressure of the tire.

6- tire according to any one of claims 1 to 5 characterized in that it comprises at least one main groove (9) of generally circumferential orientation and in that at least one cavity (8 ") filled with metal foam to form a resonator is disposed radially outside the crown reinforcement (7) of the tire, this cavity opening on both sides in each of the flanks (3) and in at least one groove main tread.

7. Tire according to any one of claims 1 to 6 characterized in that the material used to fill the cavities is a foam-type cellular material.

8- tire according to claim 7 characterized in that the foam-type cellular material is selected from foams formed from metals having melting points of less than 2000 ° Celsius such as tin, zinc, magnesium aluminum, silver, copper, manganese, silicon, nickel, cobalt, iron, titanium, zirconium, vanadium.

9- tire according to one of claims 7 or 8 characterized in that the apparent density of the metal foam material material is at least 0.5 and at most equal to 1.8.

10- tire according to any one of claims 7 to 9 characterized in that the size of the cells of the metal foam is between 1 μιη and 3 mm, and more preferably between 5 μιη and 2 mm and even more preferably between 10 μιη and 1 mm.