Tire including a high-contrast texture on the tread surface

Abstract

A tire (1) made of rubber material, comprising a tread (2), said tread having a tread surface (20) intended to come into contact with a road surface when the tire is being driven on, this tread surface having, in cross section, a certain curvature. The tread surface (20) comprises, over at least 80% of its surface, a texture (3) contrasting with the rest of the tire, this texture (3) having a plurality of elements that protrude from or are recessed into the tread surface (20), and each element extends perpendicularly (=90)to the tread surface (20) along the curvature of this tread surface (20).

Claims

1. A tire made of rubber material, comprising: a tread having a tread surface adapted to come into contact with a road surface when the tire is being driven on, the tread surface having, in cross section, a certain curvature, wherein the tread surface comprises, over at least 80% of its surface, a texture contrasting with the rest of the tire, the texture having a plurality of elements that protrude from or are recessed into the tread surface, wherein each element extends perpendicularly (=90)to the tread surface along the curvature of this tread surface, and the texture has a lightness, known as first lightness L*1, of between 6 and 15, and the rest of the tire has a lightness, known as second lightness L*2, greater than or equal to 18 and less than or equal to 30.

2. The tire according to claim 1, wherein at least 30% of the protruding elements of the texture form an angle of greater than 40 with respect to a plane tangent to the tread surface, and wherein at most 25% of the protruding elements of the texture form an angle of less than 20 with respect to the tangent plane.

3. The tire according to claim 1, wherein all or some of the protruding elements are strands distributed through the at a density at least equal to one strand per square millimeter (mm.sup.2), each strand having a mean cross section of between 0.003 mm.sup.2 and 1 mm.sup.2.

4. The tire according to claim 1, wherein all or some of the protruding elements are substantially mutually parallel lamellae, the spacing of the lamellae in the texture being at most equal to 0.5 mm, each lamella having a mean width of between 0.03 mm and 0.25 mm.

5. The tire according to claim 1, wherein all or some of the protruding elements form parallelepipeds having a side length of between 0.05 mm and 0.5 mm and a height (Hp) of between 0.05 mm and 0.5 mm, the distance between two adjacent parallelepipeds in the texture being between 0.05 mm and 0.5 mm.

6. The tire according to claim 1, wherein the protruding elements have variable shapes and distances between protruding elements in the texture.

7. The tire according to claim 1, wherein the recessed elements form openings in the tread surface and the texture comprises a plurality of openings, said openings being distributed through the texture at a density at least equal to one opening per square millimeter (mm.sup.2), these openings having, at the tread surface, equivalent diameters of between 0.03 mm and 1.2 mm.

8. The tire according to claim 1, wherein the texture present on the tread surface extends onto one sidewall of the tire.

9. The tire according to claim 8, wherein the texture on the sidewall of the tire is configured to provide a visual indication of an overload and/or underinflation of this tire.

10. The tire according to claim 1, wherein the texture has a lightness, known as first lightness L*1, of between 8 and 9.

11. A tire made of rubber material, comprising: a tread having a tread surface adapted to come into contact with a road surface when the tire is being driven on, the tread surface having, in cross section, a certain curvature, wherein the tread surface comprises, over at least 80% of its surface, a texture contrasting with the rest of the tire, the texture having a plurality of elements that protrude from or are recessed into the tread surface, each element extends perpendicularly (=90)to the tread surface along the curvature of this tread surface, the texture present on the tread surface extends onto a sidewall of the tire, and the texture on the sidewall of the tire is configured to provide a visual indication of an overload and/or underinflation of this tire.

12. The tire of claim 11, wherein the texture on the sidewall of the tire is in the form of a plurality of textured regions separated by non-textured regions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features and advantages of the invention will become apparent from the following description, given by way of non-limiting example, with reference to the attached drawings in which:

(2) FIG. 1 schematically shows a perspective view of a part of a tire having a tread in accordance with the prior art;

(3) FIG. 2 schematically shows a perspective view of a part of a tire having a particular texture on the surface of the tread, according to the invention;

(4) FIG. 3 shows a part of the texture from FIG. 2, according to a first non-limiting variant embodiment of a first embodiment of said texture, according to which the texture has protruding elements;

(5) FIG. 4 shows a part of the texture from FIG. 2, according to a second non-limiting variant embodiment of a first embodiment of said texture, according to which the texture has protruding elements;

(6) FIG. 5 shows a part of the texture from FIG. 2, according to a third non-limiting variant embodiment of a first embodiment of said texture, according to which the texture has protruding elements;

(7) FIG. 6 shows a part of the texture from FIG. 2, according to a fourth non-limiting variant embodiment of a first embodiment of said texture, according to which the texture has protruding elements;

(8) FIG. 7 shows a part of the texture from FIG. 2, according to a second embodiment of said texture, according to which the texture has recessed elements; and

(9) FIG. 8 shows an enlarged view of a cavity of a recessed element of the texture from FIG. 7.

(10) FIG. 9 presents a fifth variant embodiment in which the texture extends onto a sidewall of the tire from FIG. 2;

(11) FIG. 10 presents a sixth variant embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(12) In the following description, elements which are substantially identical or similar will be denoted by identical references.

(13) FIG. 1 shows a part of the tire 1 having a tread 2 according to the prior art. As can be seen, the tread 2 has a tread surface 20 and grooves 21. On account of the laser sintering method used, the entire tread surface 20 has level lines 4.

(14) FIG. 2 shows a part of the tire 1 having a tread 2 according to the invention. The tread 2 has a tread surface 20 and grooves 21. The tread surface 20 has, over at least 80% of its surface, a texture 3 contrasting with the rest of the tire 1, notably the sidewall of the tire 1. In the example illustrated, the texture 3 extends over the entire tread surface 20 and conceals all of the level lines 4.

(15) According to a first non-limiting embodiment of the texture 3, the texture 3 comprises a plurality of elements that protrude from the tread surface 20. The effect of these protruding elements is to trap a large amount of the incident light rays that strike the texture 3. In this first embodiment, the texture 3 (known as velvet) makes it possible to obtain not only a visual appearance of the velvet type since the protruding elements absorb light and thus make the tread surface 20 blacker, but also a touch of the velvet type, said protruding elements providing a tread surface 20 that is pleasant to the touch.

(16) Furthermore, according to one non-limiting variant embodiment, at least 30% of the protruding elements of the texture 3 form an angle of greater than 40 with respect to a plane X tangent to the tread surface, and at most 25% of the protruding elements of the texture form an angle of less than 20 with respect to the tangent plane X. The protruding elements, said tangent plane X and said angle are illustrated schematically in the zoomed-in part of the texture 3 in FIG. 2. It will be noted that the angle is the angle between the tangent plane X and the side of the protruding elements. This variant is applicable to the protruding elements 6 and 7 described below.

(17) FIG. 3 illustrates the texture 3 according to a first non-limiting variant embodiment of the first embodiment. In this variant, all or some of the protruding elements are strands 6 distributed through the texture 3 at a density at least equal to one strand per square millimeter (mm.sup.2), each strand having a mean cross section S of between 0.003 mm.sup.2 and 1 mm.sup.2 It will be noted that the mean cross section of each strand corresponds to the mean of the cross sections S measured at regular intervals from the base of the strand. The strands 6 have a conical overall shape with a cross section that decreases over the height Hb of these strands.

(18) FIG. 4 illustrates the texture 3 according to a second non-limiting variant embodiment of the first embodiment. In this variant, all or some of the protruding elements are substantially mutually parallel lamellae 7, the spacing P of the lamellae in the texture being between 0.1 mm and 0.5 mm, each lamella 7 having a mean width of between 0.03 mm and 0.25 mm. It will be noted that the mean width corresponds to the mean of the widths 1 measured at regular intervals over the height H1 of the lamella, the height of each lamella being between 0.05 and 0.5 mm.

(19) In another variant embodiment, the texture has a combination of strands 6 and lamellae 7.

(20) FIG. 5 illustrates the texture 3 according to a third non-limiting variant embodiment of the first embodiment. In this variant, all or some of the protruding elements form parallelepipeds 8 having a side length C of between 0.05 mm and 0.5 mm and a height Hp of between 0.05 mm and 0.5 mm, the distance Dp between two adjacent parallelepipeds 8 in the texture being between 0.05 mm and 0.5 mm.

(21) In another variant embodiment, the texture has a combination of elements in relief 6, 7 and 8, or 6 and 8, or 7 and 8 described above.

(22) FIG. 6 illustrates the texture 3 according to a fourth non-limiting variant embodiment of the first embodiment. In this variant, the protruding elements 9 have variable shapes and distances between protruding elements in the texture 3. This variant makes it possible to render the elements protruding from the texture 3 less visible.

(23) According to a second non-limiting embodiment of the texture 3, the texture 3 comprises a plurality of elements 10 (also known as holes) that are recessed into the tread surface 20. The recessed elements 10 are made up of openings 11 in the tread surface 20, and of associated cavities 12 extending into the depth of the tread surface 20.

(24) Thus, the texture 3 comprises a plurality of openings 11 in the tread surface 20, said openings 11 being distributed through the texture 3 at a density at least equal to one opening per square millimeter (mm.sup.2) and having, at the tread surface, equivalent diameters Dt of between 0.03 mm and 1.2 mm.

(25) In one non-limiting embodiment, the openings 11 occupy at least 30% of the texture 3.

(26) According to other non-limiting embodiments, the openings 11 occupy at least 50% of the texture 3, or even more than 70%. It will be noted that the greater the rate of occupation of the texture by the openings, the better the concealment of the level lines brought about by the moulding method is, and the better this texture contrasts with the rest of the tread.

(27) The openings 11 continue into the depth of the tread surface 20 to form cavities 12.

(28) The effect of these cavities 12 is to trap a large amount of the incident light rays that strike the texture 3, but also to make the texture 3 more durable. Specifically, since the cavities 12 are recessed into the tread surface 20, the impact of mechanical attack on the texture, such as rubbing by a road surface, is lower than for protrusions. In this second embodiment, the texture 3 (known as velvet) makes it possible to obtain a visual appearance of the velvet type since the cavities absorb light and thus make the tread surface 20 blacker.

(29) In one non-limiting embodiment, all or some of the cavities 12 have a depth at least equal to 0.1 mm. In one non-limiting variant embodiment, all or some of the cavities 12 have a depth of between 0.2 mm and 0.6 mm. This ensures that a large amount of incident light rays that strike the texture 3 are trapped by said texture and, since the depth of the cavities is limited, also prevents the mechanical strength of the tread surface 20 from deteriorating excessively.

(30) FIG. 7 illustrates the texture 3 according to a first non-limiting variant of this second embodiment. In this variant, all or some of the cavities 12 are in the form of cones which extend into the depth of the tread surface 20 and lead onto the tread surface, forming circular openings 11. The cavities 12 thus have a cross section which decreases with depth into the tread surface 20. This improves the contrast of the texture 3 and thus of the tread surface 20 with respect to the rest of the tread 2. It will be noted that in this variant, the openings 11 of the cavities 12 are not in contact. The openings 11 are separated by intermediate regions 13. Moreover, the openings 11 are distributed regularly over all or some of the tread surface 20 such that the distance d between each opening in the texture is similar overall.

(31) FIG. 8 is a zoomed-in view of a cavity 12 of a recessed element 10 of the texture from FIG. 7. In one non-limiting embodiment, all or some of the cavities have at least one wall 14 which, in cross section, forms an angle of between 10 and 60 with respect to a direction Z perpendicular to the texture 3.

(32) Each time a light ray strikes a wall 14 of the cavity 12, this ray is reflected by said wall 14. The direction of reflection of the light ray depends on the initial direction of this light ray and on the inclination angle of the wall 14. Thus, depending on this initial direction and on this inclination angle, the light ray can be sent towards another wall 14 of the cavity. By contrast, the light ray can be sent to the outside of the cavity, for example directly towards an observer. In the first case, the light ray is lost in the cavity and will no longer be perceptible to an observer. In the second case, the observer can perceive the light ray and the texture can then appear to be lighter and thus to contrast less with the rest of the tread. Choosing a cavity 12 having at least one wall 14 which forms an angle of between 10 and 60 ensures that a large part of the light rays entering the cavity 12 will be absorbed by this cavity under the effect of multiple reflections inside the cavity. This improves the contrast of the texture 3 (and thus of the tread surface 20) with respect to the rest of the tire 1 (notably with respect to the sidewall), while preserving the same rate of occupation of the texture by the cavities. Moreover, with this wall inclination, the strength of the texture is improved overall, notably in the event of repeated rubbing against the road surface.

(33) The invention is not limited to the examples described and shown and various modifications can be made thereto without departing from its scope.

(34) Thus, according to another non-limiting variant embodiment, the lamellae 7 from FIG. 4 can be discontinuous. They have a flat part between one another. They can also have cross-sectional differences between one another. In addition, the lamellae can have curves or angles, notably along their length. They can also have a variable length.

(35) Thus, according to another non-limiting variant embodiment, the openings 11 can have a circular, square or polygonal (for example hexagonal) shape and the corresponding cavities 12 can have a cylindrical, parallelepipedal or polygonal shape. With these two latter structures (square or polygonal), it is possible to more easily organize the openings 11 with respect to one another so as to limit the area of the intermediate regions 13 between these openings. With such opening shapes, it is easier to achieve consistent rates of occupation of the openings.

(36) FIGS. 9 and 10 present variant embodiments in which the texture 3 continues onto a part of the sidewall 22 of the tire. In FIG. 10, the texture 3 continues so as to form textured regions 23 interrupted by non-textured regions 24, so as to form means for indicating overload and/or underinflation. The textured regions 23 of the sidewall can have a particular geometric shape so as to make it easier to see these means for indicating overload and/or underinflation.

(37) Thus, the invention described has notably the following advantages: The texture 3 makes it possible to conceal the level lines on the tread surface; The texture 3 (regardless of whether it has protruding elements and/or recessed elements) makes it possible at the same time to absorb light and thus to give the tread surface 20 a blacker appearance compared with the rest of the tread 2. This improves the contrast of the tread surface 20 with respect to the rest of the tread; and The texture 3 makes it possible to obtain an appearance of the tread surface 20 and/or a touch that is pleasant at the tread surface 20, of the velvet type.

(38) The scope of protection of the invention is not limited to the examples given hereinabove. The invention is embodied in each novel characteristic and each combination of characteristics, which includes every combination of any features which are stated in the claims, even if this feature or combination of features is not explicitly stated in the examples.