TIRE FOR ATTENUATING ROLLING NOISE

Abstract

Present disclosure provides a tire including a summit surrounded on both sides by sidewalls, including a carcass reinforcement extending in the summit and the sidewalls, and anchored at its two ends in the beads, the carcass reinforcement being surmounted radially on the outside by a summit reinforcement composed of a plurality of reinforcing plies, said summit reinforcement being surmounted radially on the outside by a tread intended to come into contact with a ground during use of the tire, the tire comprising in its summit, at least one cavity acting as a resonator and in fluid communication with the outside of the tire, when the tire is mounted onto a mounting rim each cavity having an appropriate volume to form a calibrated resonator to attenuate the noise in a frequency range between 500 and 2000 Hz.

Claims

1. Tire mounted on a mounting rim, comprising: a summit surrounded on both sides by sidewalls terminating in beads to cooperate with the mounting rim of the tire; a carcass reinforcement extending in the summit and the sidewalls, and anchored at its two ends in the beads, the carcass reinforcement being surmounted radially on the outside by a summit reinforcement composed of a plurality of reinforcing plies, said summit reinforcement being surmounted radially on the outside by a tread that contacts with a ground during use of the tire, wherein the summit includes at least one cavity acting as a resonator and in fluid communication with an outside of the tire, when the tire is mounted onto the mounting rim each cavity has an volume configured to form a calibrated resonator to attenuate the noise in a frequency range between 500 and 2000 Hz, each cavity being arranged substantially uniform in the circumferential direction and is filled with a fibrous or a filamentary material.

2. Tire according to claim 1, wherein said tread includes at least one groove, and each cavity being formed radially inward of the groove and each cavity is adapted to open to the groove.

3. Tire according to claim 2, further comprising a plurality of cavities, and each cavity is separately placed in the circumferential direction and each cavity opens to the groove.

4. Tire according to claim 2, further comprising a plurality of cavities, and each cavity is separately placed in the transverse direction and each cavity opens to the groove.

5. Tire according to claim 1, wherein further comprising a plurality of cavities, and each cavity is separately placed in circumferential and transverse directions and the cavities being distributed uniformly in transverse direction.

6. Tire according to claim 1, further comprising the cavity is formed so as not to come in contact with the ground after wear of the tread until a predefined amount is not reached.

7. Tire according to claim 1, wherein the fibrous or the filamentary material filling the cavities is a fabric material.

8. Tire according to claim 7, wherein the fabric material is selected from the group consisting of woven fabric, unwoven fabric and mixture of these fabrics.

9. Tire according to claim 7, wherein an apparent density of the fabric material is at least equal to 0.05 and at most equal to 0.5 g/cm.sup.3 according to JIS Z 8807.

10. Tire according to claim 7, wherein an air permeability of the fabric material is at least equal to 10 g/cm.sup.3/cm.sup.2/s according to JIS L 1096.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Other characteristics and advantages of the invention appear from the description given hereinafter with reference to the accompanying drawings which show, by way of non-limiting examples, embodiments of the present invention.

[0044] FIG. 1 is an exploded view of a summit portion of a tire according to a first embodiment of the present invention;

[0045] FIG. 2 shows a meridian section of the summit of the tire shown in FIG. 1;

[0046] FIG. 3 is an exploded view of a tire according to a second embodiment of the present invention;

[0047] FIG. 4 shows a meridian section of the summit of the tire shown in FIG. 3;

[0048] FIG. 5 is a plan view of a summit surface of the tire according to a third embodiment of the present invention;

[0049] FIG. 6 is a partially cut-way perspective view showing a section of a summit of the tire according to a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0050] To facilitate the understanding of the arrangement of the embodiment, the same reference numerals are used to refer to elements of the same nature in the description.

[0051] FIG. 1 is an exploded view of a tire according to a first embodiment of the present invention. FIG. 2 shows a meridian section (that is to say in a plane containing the axis of rotation of the tire) of a summit of the tire shown in FIG. 1.

[0052] In the first embodiment, the tire 1 having size 205/55R16 comprises a summit 2 connected at its axial ends to sidewalls 3 terminating in beads 4. The tire 1 also comprises a carcass reinforcement 5 extending in the summit 2 and the sidewalls 3, and anchored at both ends in the beads 4.

[0053] The carcass reinforcement 5 is surmounted radially on the outside by a summit reinforcement 6 including belt plies 61, 62, 63. Two belt plies 61, 62 are crossed from the other ply or a cap ply 63. The summit reinforcement 6 is surmounted by a tread 7 intended to come into contact with the ground during use of the tire.

[0054] The tread 7 includes four main grooves 8 extending generally in circumferential direction and a plurality of transverse grooves 9. These circumferential and transverse grooves defining a plurality of blocks 10 in the tread 7.

[0055] in the present embodiment, each main groove 8 has a width of 6 mm and a depth of 6 mm. This dimension is suitable to reserve a thickness of rubber material between a groove bottom and the summit reinforcement 6. As shown in FIGS. 1 and 2, radially inward of the main grooves 8, a cavity 11 having a rectangular cross section is provided. The cavity 11 is sized or made so as to function as a resonator to attenuate at least partially the noise in a frequency range between 500 and 2000 Hz, such as Helmholtz or quarter-wave type resonator.

[0056] The cavity 11 has a uniform rectangular cross section in circumferential direction and specifically has a width in the transverse direction (direction of the axis of tire rotation) of 140 mm and a height (thickness) in radial direction of 3 mm. The cavity 11 continuously extends in a circumferential direction so as to form cylindrical space in the summit 2.

[0057] This cavity 11 is transversely centered on the equatorial plane of the tire (indicated by the line XX in FIG. 2) and has a transverse width substantially equal to the width of the second belt ply 62 of the summit reinforcement. The distance between a bottom surface of the groove 8 and a radially outer surface of the cavity 11, is preferably 0.5 mm or more.

[0058] In the bottom of the main groove 8, an exhaust groove 12 is provided. The exhaust groove (neck) 12 continuously extends in the circumferential direction along the entire length of the main groove 8. One radial end of the exhaust groove 12 is connected to the cavity 11 and the other radial end of the exhaust groove 12 is open to the bottom of the main groove 8 so that the cavity 11 opens to the main groove 8 through the exhaust groove 12. The other radial end of the exhaust groove 12 may open to other part of the main groove 8.

[0059] Each exhaust groove 12 has a width of 6 mm measured in the transverse direction and a height of 0.5 mm.

[0060] The exhaust groove 12 may be discontinuous in circumferential direction in order to maintain sufficient tread stiffness, especially in transverse bending (that is to say heading about an axis tangent to the circumferential direction).

[0061] The cavity 11 is filled with an unwoven fabric, for example an unwoven fabric sold under the trade name Flextar(trademark) by Kuraray Co., Ltd,. Density of the unwoven fabric is 0.10 g/cm.sup.3 according to ITIS Z 8807, and an air permeability of the unwoven fabric is 26.2 g/cm.sup.3/cm.sup.2is according to JIS L 1096.

[0062] The unwoven fabric is introduced into the tire during molding and vulcanization step in manufacturing process of the tire. The unwoven fabric filling the cavity combined with the main grooves 8 forms a resonator capable of reducing noise generated between the tread and the ground.

[0063] With such an arrangement, there is a attenuation of the acoustic emission of the order of 2.2 dB at 70 kph according to ECE R117 (Directive 2005/11/EC) compared to the same tire devoid of any anti rolling noise resonator.

[0064] In the first embodiment, the material filling the cavity 11 is sufficiently distant from the rolling surface (contact face) of the tread 7 so as not to interfere with the conditions of contact of the tire on a ground even after partial wear.

[0065] FIG. 3 is an exploded view showing a tire according to a second embodiment of the present invention. FIG. 4 shows a meridian section of the summit portion of the tire shown in FIG. 3.

[0066] A tire according to the second embodiment has the substantially the same structure as that shown in FIG. 1 except that a cap ply is not provided and that four cavities 111, 112, 113, 114 acting as Helmholtz resonator are provided separately from each other in a transverse direction.

[0067] In the second embodiment, each cavity 111, 112, 113, 114 is formed to be located radially inwardly of the main grooves 8, respectively. Each cavity is filled with a fibrous or a filamentary material and has an appropriate volume so as to act as a Helmholtz resonator.

[0068] In the bottom of the main groove 28, a plurality of wells (through necks) 13 is provided. A radially inward end of the well 13 is connected to the cavity 111, 112, 113, 114 and a radially outward end of the well 13 is open to the main groove 8 so that the cavity 111, 112, 113, 114 opens to the main groove 8 through the well 13.

[0069] Each cavity 111, 112, 113, 114 has a uniform rectangular cross section in circumferential direction and continuously extends in the circumferential direction so as to form cylindrical space in the summit 2.

[0070] Alternatively, the main groove may be obliquely oriented with respect to a circumferential direction by an average angle from zero and less than 90. In this case, the cavities are oriented in the same manner as the main groove. Preferably, the average angle of the groove is with respect to the circumferential direction between 15 and 50. In this case, each main groove may extend from one edge to the other of the tread of the tire or from around axially the center of the tread to one edge of the tread of the tire, and each cavity may extend also from one edge to the other of the summit of the tire or from around axially the center of the summit to one edge of the summit of the tire. The cavities may be oriented in different direction toward the direction which the grooves are oriented.

[0071] FIG. 5 is a plan view of a summit surface of the tire according to a third embodiment of the present invention.

[0072] In this embodiment, a plurality of cavities 116 is circumferentially arranged in a radially inward position of the main grooves 8. As shown in FIG. 5, each of cavities 116 has an elongated shape and extends in a transverse direction so as to perpendicularly traverse the main grooves 8. That is, the plurality of cavities 116 is uniformly arranged in a circumferential direction.

[0073] The cavity 116 is filled with a fibrous or a filamentary material. Each cavity 116 is in connection to three main grooves 8 through a neck which circumferentially opens. The cavities 16 are not connected to each other in the circumferential direction and extend in the whole transverse width of the summit reinforcement (in the direction YY parallel to the tire rotation direction).

[0074] Advantageously, this arrangement does not change bending flexibility too much in the flattening of the tread in the region of contact with the ground. Alternatively, the cavities can be oriented obliquely to a non-zero angle with the direction YY.

[0075] FIG. 6 is a partially cut-way perspective view showing a tire summit according to a fourth embodiment of the present invention. In this embodiment, a tread comprises a plurality of blocks 10 separated from each other or delimited by circumferential main grooves 8 and transverse grooves 9. A cavity 115 is independently formed in each block 10. In a contact face 100 of each block 10, is provided a through neck 14 radially oriented and connecting the cavity 115 and the outside space of the tire. The cavities are uniformly arranged in a circumferential direction. The cavity 115 is filled with a fibrous or a filamentary material and acts as a resonator.

[0076] According to this arrangement, the cavity 115 can be directly connected to a space formed between the ground and the contact face via the through neck 14.

[0077] Advantageously, the cavity 115 is formed at a radially inner position with respect to the legal wear limit of the tread so that the filling material does not interfere with the ground during rolling. In the fourth embodiment, a wear limit indicator 15 showing legal wear limit is provided at the bottom of the main groove 8. Since the filling material in each cavity is positioned at a radially inner position than the wear limit indicator 15, the filling material does not come into contact with the ground during the legally permitted use.