Noise-reducing device intended to be inserted into a groove in the tread of a tire and tire comprising a device of this type

Abstract

Noise-reducing device intended to be added to a groove of the tread of a tire comprising an elastic sole preferably extending in a given longitudinal direction, wherein the said sole on one of its faces comprises one or several flexible walls the planes of which run substantially perpendicular to the longitudinal direction of the sole.

Claims

1. A noise-reducing device in a groove of a tread of a tire, the device comprising an elastic sole extending in a longitudinal direction, the sole being substantially flat and disposed in a substantially flat bottom wall of the groove, one or more grooves of depth (h) and of width (w), wherein the sole comprises a face having one or more flexible walls extending therefrom, each flexible wall having a plane that extends substantially perpendicular to the longitudinal direction of the sole, and wherein a plurality of the flexible walls are spaced apart in the longitudinal direction by a length of between 10 mm and 50 mm, and at least one groove comprises at least one noise-reducing device, and the noise-reducing device is bonded to the radially internal wall of the groove of the tire, by only the elastic sole, the sole comprises two longitudinal ends that taper in the thickness direction, wherein the circumference of the sole is less than the circumference of the bottom of the groove of the tire.

2. The noise-reducing device according to claim 1, wherein the flexible walls have a thickness of between 0.5 mm and 2 mm.

3. The noise-reducing device according to claim 1, wherein the material used to make the said device is a rubber-containing elastomer.

4. The noise-reducing device according to claim 3, wherein the walls and the sole are made from the same material.

5. The tire according to claim 1, wherein the flexible walls of the noise-reducing device increased by the thickness (e) of the sole have a height less than or equal to the depth (h) of the groove.

6. The tire according to claim 1, wherein the flexible walls and the sole of the noise-reducing device have a width less than or equal to the width (w) of the groove.

7. The noise-reducing device according to claim 1, wherein the sole comprises a second face, opposing the face from which the walls extend, adapted to contact one or more internal surfaces of a groove of a tire.

8. The noise-reducing device according to claim 1, wherein the longitudinal direction of the sole is substantially parallel to the circumferential direction of a groove of a tire.

9. The tire according to claim 1, wherein the longitudinal direction of the sole is substantially parallel to the circumferential direction of a groove of the tire.

10. The tire according to claim 1, wherein the longitudinal edges taper to a maximum thickness at a point where the at least one of the flexible walls extends therefrom.

11. A noise-reducing device in a groove of a tread of a tire, the device comprising an elastic sole extending in a longitudinal direction, the sole being substantially flat and disposed in a substantially flat bottom wall of the groove, wherein the sole comprises a face having one or more flexible walls extending therefrom, each flexible wall having a plane that extends substantially perpendicular to the longitudinal direction of the sole, and wherein the material used to make the device is a thermoplastic elastomer, and at least one groove comprises at least one noise-reducing device, and the noise-reducing device is bonded to the radially internal wall of the groove of the tire, by only the elastic sole, the sole comprises two longitudinal ends that taper in the thickness direction, wherein the circumference of the sole is less than the circumference of the bottom of the groove of the tire.

12. The noise-reducing device according to claim 11, wherein the walls and the sole are made from the same material.

13. A noise-reducing device in a groove of a tread of a tire, the device comprising an elastic sole extending in a longitudinal direction, the sole being substantially flat and disposed in a substantially flat bottom wall of the groove, wherein the sole comprises a face having one or more flexible walls extending therefrom, each flexible wall having a plane that extends substantially perpendicular to the longitudinal direction of the sole, and wherein the sole comprises two longitudinal ends that taper in the thickness direction, and at least one groove comprises at least one noise-reducing device, and the noise-reducing device is bonded to the radially internal wall of the groove of the tire, by only the elastic sole, the sole comprises two longitudinal ends that taper in the thickness direction, wherein the circumference of the sole is less than the circumference of the bottom of the groove of the tire.

14. A noise-reducing device in a groove of a tread of a tire, the device comprising an elastic sole extending in a longitudinal direction, the sole being substantially flat and disposed in a substantially flat bottom wall of the groove, wherein the sole comprises a face having one or more flexible walls extending therefrom, each flexible wall having a plane that extends substantially perpendicular to the longitudinal direction of the sole, and wherein the sole comprises two longitudinal ends of the sole that butt together so that the sole forms a continuous elastic ring in which the flexible walls are situated radially on the outside of the ring, and at least one groove comprises at least one noise-reducing device, and the noise-reducing device is bonded to the radially internal wall of the groove of the tire, by only the elastic sole, the sole comprises two longitudinal ends that taper in the thickness direction, wherein the circumference of the sole is less than the circumference of the bottom of the groove of the tire.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The description which follows is supported by FIGS. 1 to 7 in which:

(2) FIG. 1 depicts a partial schematic view of a tire comprising flexible walls arranged in the circumferential grooves,

(3) FIG. 2 illustrates in a view in section of a noise-reducing device according to the invention,

(4) FIGS. 3 and 4 illustrate perspective views of noise-reducing devices according to the invention,

(5) FIG. 5 illustrates one example of the positioning of a noise-reducing device according to the invention, by bonding it into the bottom of a groove of a tire,

(6) FIGS. 6 and 7 illustrate the positioning of noise-reducing devices according to one particular embodiment of the invention in a groove of a tire.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

(7) The portion of tire T depicted in FIG. 1 comprises a plurality of grooves L.sub.1, L.sub.2, L.sub.3 and L.sub.4 running in the circumferential direction of the tread. By way of example, two of these grooves L.sub.1 and L.sub.3, are equipped with flexible walls P. These walls are securely articulated to the bottom wall of the groove and are alternately angled about this connection in the directions indicated by the double-headed arrow drawn over the top of the flexible wall P of the groove L.sub.3.

(8) FIGS. 3 and 4 illustrate one first embodiment of noise-reducing devices according to the invention, and which comprises a sole S comprising one or more flexible walls P the planes of which are positioned substantially perpendicular to the longitudinal direction of the said sole S.

(9) The two longitudinal ends of the sole S taper in the thickness direction. This contrivance improves the retention of the sole when the noise-reducing device is bonded into the bottom of a groove L.

(10) FIG. 2 depicts, in a view in section, a noise-reducing device according to the invention, arranged in a groove of depth h and of width w. It is then contrived for the width of the sole S and the width of the wall P to be less than or equal to the width w of the groove, and for the height of the wall P, increased by the thickness e of the sole to be less than or equal to the depth h of the groove.

(11) The noise-reducing device may be made from a rubber-based or a thermoplastic-based elastomeric material. The material chosen for making the flexible wall will preferably be a material that has the best properties of flexing, in particular a material the elastic modulus of which allows opening under the action of the pressure of the water and closing when only the pressure of the air is acting on the two faces at the usual running speeds of the vehicle intended to be fitted with the tire equipped with the noise-reducing device thus defined. This parameter may also be adjusted by altering the thickness of the flexible wall, which is advantageously between 0.5 mm and 2 mm.

(12) Likewise, the material of the sole will have the elastic properties that allow it to accompany the movements of the tread while at the same time displaying good compatibility with the bonding means employed to cause the underside face of the sole of the noise-reducing device to adhere to the material of which the tread is made.

(13) For practical reasons associated with the production thereof, and although it is entirely possible to produce noise-reducing devices using different composite materials for the flexible wall and for the sole, these devices will be made of one and the same material, adjusting the dimensional parameters of the flexible wall in order to suit the desired flexural functionalities.

(14) The spacing between two successive flexible walls is also determined by the characteristics of the vehicle on which a tire fitted with devices according to the invention is to be mounted and for which as a general rule it is desirable for several devices to be simultaneously present in the contact patch. For the most commonplace use, this distance is between 10 mm and 50 mm.

(15) The choice of bonding means will be adapted to suit the nature of the materials of which the tread and the sole of the noise-reducing device are made. In particular, care will be taken to ensure that the quality of the bond is compatible with the centrifugal forces generated by high-speed running.

(16) The material of which the sole is made can be made using any type of elastomeric material, provided that the bonding system is suited to bonding the sole to the material used for the tread of the tire.

(17) By way of example, for a tread made of a diene elastomer or of a thermoplastic elastomer, a sole may be chosen that is made from a diene elastomer of the same type or from a material of the thermoplastic elastomer, polyurethane type, a silicone-based material, or even a material formed of an elastomer of the butyl type or EPDM. In these various instances the adhesive used will, depending on the pairs of materials chosen, be an adhesive of the polyurethane-urea type with a surface activator or a poly-urea adhesive with a surface primer. Bonding may be performed in the hot state or at a temperature slightly higher than ambient temperature.

(18) It will be noted at this stage that, when the noise-reducing device is bonded into the bottom of the groove of the tread of a tire, it is of low importance whether this groove is oriented in an essentially circumferential or axial direction. All that is important is that its length be greater than or equal to the length of the sole.

(19) FIGS. 6 and 7 illustrate an alternative form of embodiment which proves to be particularly advantageous when it is desirable to equip tires the tread of which has grooves running essentially in the circumferential direction.

(20) According to this embodiment, the two longitudinal ends of the sole are joined to form a ring. The flexible walls are positioned radially towards the outside of the ring. All that is required therefore is the choice of a continuous elastic ring the free circumference of which is slightly smaller than the circumference of the bottom of the groove of the tire into which this noise-reducing device is to be positioned so that the elastic sole is under tension when the ring is placed in the bottom of the groove of the tread. This tension provides the grip needed to keep the noise-reducing device in the groove of the tread during running.

(21) There is then no longer any need for the sole to be bonded to the bottom of the groove, although such bonding is still recommended.