Tire Comprising at Least One Sidewall with a Protective Protuberance

Abstract

A tire (1), intended in particular for a private passenger vehicle and comprising at least one sidewall (3) with a protuberance of the sidewall (3) close to the connection of the tire with its mounting rim (2), and intended to reduce the aerodynamic drag and hence the resistance to forward motion of the wheel, in order to contribute to the reduction in fuel consumption and hence to the reduction in CO2 emissions. According to the invention, when the tire (1) is mounted on the rim (2) and inflated to a pressure as defined by the “ETRTO” standard, the radially inner end I of the protuberance (6) is positioned radially inside the radially outermost point J of the rim flange (21) at a radial distance H1 at most equal to 10 mm, or radially outside the radially outermost point J of the rim flange (21) at a radial distance H1 at most equal to 4 mm.

Claims

1. A tire for a private passenger vehicle, intended to be mounted on a im as defined by the standard of “European Tire and Rim Technical Organisation” or “ETRTO”, comprising: two sidewalls connecting a crown to two respective beads, each intended to come into contact with a rim flange having a radially outermost point J, at least one sidewall comprising a protuberance intended to protect a rim flange and extending radially inward from an axially outer face of the sidewall and circumferentially in a circumferential direction (XX′) of the tire, the protuberance having, in any meridian plane (YZ) containing the rotational axis (YY′) of the tire, a meridian section delimited by a contour having a radially innermost point, called the radially inner end I of the protuberance (6), wherein when the tire is mounted on the rim and inflated to a pressure as defined by the “ETRTO” standard, the radially inner end I of the protuberance is positioned radially inside the radially outermost point J of the rim flange at a radial distance H1 at most equal to 10 mm or radially outside the radially outermost point J of the rim flange at a radial distance H1 equal at most to 4 mm.

2. The tire according to claim 1, wherein the rim flange comprises, in any meridian plane (YZ), a radially outer circular portion linked by an intermediate radial portion to a radially inner, substantially axial portion, and wherein the radially inner end I of the protuberance is positioned axially outside the radial portion of the rim flange at an axial distance B1 at least equal to 5 mm.

3. The tire according to claim 1, wherein the rim flange comprises, in any meridian plane (YZ), a radially outer circular portion linked by an intermediate radial portion to a radially inner, substantially axial portion, and wherein the radially inner end I of the protuberance is positioned axially outside the radial portion of the rim flange at an axial distance B1 at most equal to 21 mm.

4. The tire according to claim 1, wherein the meridian section of the protuberance having a larger dimension in a middle direction D1, and wherein the middle direction D1 of the meridian section of the protuberance forms, with a radial direction (ZZ′), an angle A at least equal to 5°.

5. The tire according to claim 1, wherein the meridian section of the protuberance has a larger dimension in a middle direction D1, and wherein the middle direction D1 of the meridian section of the protuberance forms, with a radial direction (ZZ′), an angle A at most equal to 30°.

6. The tire according to claim 1, wherein the contour of the protuberance comprises an axially inner connection point K of the protuberance to the axially outer face of the sidewall, wherein the straight line tangent to the contour has an axial direction (YY′), positioned radially outside the radially outermost point J of the rim flange at a radial distance H2 at least equal to 3 mm.

7. The tire according to claim 6, wherein the axially inner connection point K of the protuberance to the axially outer face of the sidewall is positioned radially outside the radially outermost point J of the rim flange at a radial distance H2 at most equal to 10 mm.

8. The tire according to claim 6, wherein the axially inner connection point K of the protuberance to the axially outer face of the sidewall is positioned axially outside the radially outermost point J of the rim flange.

9. The tire according to claim 6, wherein the connection radius R, defined as the radius of curvature at the axially inner connection point K of the protuberance to the axially outer face of the sidewall, is at least equal to 2 mm.

10. The tire according to claim 6, wherein the thickness E of the meridian section of the protuberance measured along the axial line D2, radially inside the axially inner connection point K of the protuberance to the axially outer face of the sidewall and positioned at a radial distance H3 therefrom equal to 3 mm, is at least equal to 1.5 mm.

11. The tire according to claim 6, wherein the thickness E of the meridian section of the protuberance measured along the axial line D2, radially inside the axially inner connection point K of the protuberance to the axially outer face of the sidewall and positioned at a radial distance H3 therefrom equal to 3 mm, is at most equal to 8 mm.

12. The tire according to claim 1, wherein the protuberance is in contact with the rim flange via at least one contact means distributed circumferentially.

13. The tire according to claim 1, wherein each sidewall comprises a protuberance.

14. The tire according to claim 1, the tire having a radially outermost point M in a median plane (XZ), and a theoretical height H in the sense of the “ETRTO” standard, measured between the radially outermost point M of the tire and the radially innermost point of the rim flange, wherein the tire has, on the axially outer face of each sidewall, an axially outermost point N positioned radially, relative to the radially outermost point M, at a radial distance H4 at least equal to H/2+5 mm.

15. A mounted assembly comprising a tire according to claim 1, mounted on its rim.

Description

[0038] The characteristics of the invention are illustrated in schematic FIGS. 1 to 5, and not shown to scale:

[0039] FIG. 1 is a meridian half-section of a tire mounted on a rim in a first embodiment of the invention, with a radially inner end of the protuberance radially inside the rim flange.

[0040] FIG. 2 is a meridian half-section of a tire mounted on a rim in a second embodiment of the invention, with a radially inner end of the protuberance radially outside the rim flange.

[0041] FIG. 3 is a local view of the connection of a tire bead to its rim according to a preferred variant of the first embodiment of the invention.

[0042] FIG. 4 is a local view of the connection of a tire bead to its rim according to a first variant of the first embodiment of the invention.

[0043] FIG. 5 is a meridian half-section of a tire mounted on a rim in a second variant of the first embodiment of the invention, with a radially inner end of the protuberance radially inside the rim flange.

[0044] FIG. 1 shows a meridian half-section in a meridian plane YZ of a tire 1 mounted on its rim 2, according to a first embodiment of the invention, with a radially inner end I of the protuberance 6 radially inside the rim flange 21. The tire 1 for a private passenger vehicle, intended to be mounted on a rim 2 as defined by the standard of the “European Tire and Rim Technical Organisation” or “ETRTO”, comprises two sidewalls 3 linking a crown 4 to two respective beads 5, each intended to come into contact with a rim flange 21 having a radially outermost point J. At least one sidewall 3 comprises a protuberance 6 intended to protect a rim flange 21 and extending radially towards the inside from an axially outer face 31 of the sidewall and circumferentially in a circumferential direction XX′ of the tire. In the meridian plane YZ containing the rotational axis YY′ of the tire, the protuberance 6 has a meridian section delimited by a contour having a radially innermost point, known as the radially inner end I of the protuberance 6. According to the first embodiment of the invention, when the tire 1 is mounted on the rim 2 and inflated to a pressure as defined by the ETRTO standard, the radially inner end I of the protuberance 6 is positioned radially inside the radially outermost point J of the rim flange 21, at a radial distance H1 at most equal to 10 mm.

[0045] FIG. 2 shows a meridian half-section of a tire mounted on a rim according to a second embodiment of the invention, with a radially inner end of the protuberance radially outside the rim flange. According to the second embodiment of the invention, when the tire 1 is mounted on the rim 2 and inflated to a pressure as defined by the ETRTO standard, the radially inner end I of the protuberance 6 is positioned radially outside the radially outermost point J of the rim flange 21, at a radial distance H1 at most equal to 4 mm

[0046] [FIG. 3]

[0047] FIG. 3 is a local view of the connection of a bead 5 of the tire 1 with its rim 2 according to a preferred variant of the first embodiment of the invention, in which the radially inner end I of the protuberance 6 is radially inside the rim flange 21. More precisely, the radially inner end I of the protuberance 6 is the radially inner end I of the contour 62 of the meridian section 61 of the protuberance 6. As shown in FIG. 1, when the tire 1 is mounted on the rim 2 and inflated to a pressure as defined by the ETRTO standard, the radially inner end I of the protuberance 6 is positioned radially inside the radially outermost point J of the rim flange 21, at a radial distance H1 at most equal to 10 mm. The rim flange 21 comprises, in the meridian plane YZ, a radially outer circular portion 211 connected by an intermediate radial portion 212 to a substantially axial, radially inner portion 213. It also has an axial width B measured between the radial portion 212 and the axially outer end L of the circular portion 211. In this variant of the first embodiment, the radially inner end I of the protuberance 6 is positioned axially outside the radial portion 212 of the rim flange 21, at an axial distance B1 at least equal to 5 mm, preferably at least equal to 8 mm, and at most equal to 21 mm, preferably at most equal to 16 mm. The meridian section 61 of the protuberance 6 having a greatest dimension in a middle direction D1, the middle direction D1 of the meridian section 61 of the protuberance 6 forms, with a radial direction ZZ′, an angle A at least equal to 5°, preferably at least equal to 10°, and at most equal to 30°, preferably at most equal to 20°. Furthermore, the contour 62 of the protuberance 6 comprises an axially inner connection point K of the protuberance 6 to the axially outer face 31 of the sidewall, wherein the straight line tangent to the contour 62 has an axial direction YY′ positioned radially outside the radially outermost point J of the rim flange 21, at a radial distance H2 at least equal to 3 mm and at most equal to 10 mm. In addition, the axially inner connection point K of the protuberance 6 to the axially outer face 31 of the sidewall is positioned axially outside the radially outermost point J of the rim flange 21. The connection radius R at point K is at least equal to 2 mm Finally, thickness E of the meridian section 61 of the protuberance 6 measured along the axial line D2, radially inside the axially inner connection point K of the protuberance 6 to the axially outer face 31 of the sidewall and positioned at a radial distance H3 therefrom equal to 3 mm, is at least equal to 1.5 mm and at most equal to 8 mm

[0048] [FIG. 4]

[0049] FIG. 4 is a local view of the connection of a bead 5 of the tire 1 to its rim 2 according to a first variant of the first embodiment of the invention, with a radially inner end I of the protuberance 6 radially inside the rim flange 21. In the variant shown, the protuberance 6 is in contact with the rim flange 21 via two contact means 63 in relief relative to the protuberance 6 and distributed circumferentially, either continuously or discontinuously.

[0050] FIG. 5 is a meridian half-section of a tire 1 mounted on its rim 2 according to a second variant of the first embodiment of the invention, with a radially inner end I of the protuberance 6 radially inside the rim flange 21. In the variant shown, the tire 1 having a radially outermost point M in a median plane XZ, and a theoretical height H in the sense of the ETRTO standard measured between the radially outermost point M of the tire 1 and the radially innermost point of the rim flange 21, the tire 1 has, on the axially outer face 31 of each sidewall 3, an axially outermost point N radially positioned, relative to the radially outermost point M, at a radial distance H4 at least equal to H/2+5 mm, wherein H/2 is half the sidewall height measured between the radially outermost point M of the tire 1 and the point P halfway up the sidewall 3. This is a typical sidewall geometry of a short sidewall tire, in which the radial height H in the sense of the ETRTO standard preferably lies between 75 mm and 105 mm.

[0051] The inventors have studied this invention more particularly for a tire I1 of dimension 235/60 R 18, intended to carry a recommended load equal to 875 kg, and a tire I2 of dimension 245/35 R 20, intended to carry recommended load equal to 615 kg. For each of these two tires I1 and I2, the geometric dimensions were determined on the tire mounted on the rim and inflated to a pressure equal to 2.5 bar.

[0052] The inventors simulated the mechanical and aerodynamic behaviour of two exemplary embodiments I1 and I2, respectively 235/60 R 18 and 245/35 R 20, using a finite element calculation method, and were able to verify the efficacy of such a design with respect to delaying the detachment of the air flow at the sidewall of the tire.

[0053] The main geometric characteristics of the two examples studied are shown in the table below:

TABLE-US-00001 TABLE 1 I1 I2 Characteristics (235/60 R 18) (245/35 R 20) Axial width B of rim flange 21 (mm) 11.6 mm 12.7 mm Radial distance H1 between points I 7.5 mm 0 mm and J (mm) Axial distance B1 between point I and 12.8 mm 14.3 mm the radial portion 212 of the rim flange 21 (mm) Radial distance H2 between points K 4.8 mm 4 mm and J (mm) Radial distance H3 between point 3 mm 3 mm K and line D2 at which the thickness E is measured (mm) Thickness E (mm) 2.2 mm 2 mm Angle A of middle direction D1 (°) 12° 13°