Patent ID: 12257862

DETAILED DESCRIPTION OF THE FIGURES

In this document, “tread surface” means all of the points of the tread of a tire that are likely to come into contact with the ground when the tire is being driven on.

When using the term “radial”, a distinction should be made between several different uses of the word by a person skilled in the art.

Firstly, the expression refers to a radius of the tire. A “radial direction” is a direction that intersects the axis of rotation of the tire and is perpendicular thereto. It is within this meaning that a point P1is said to be “radially inside” a point P2(or “radially on the inside” of the point P2) if it is closer to the axis of rotation of the tire than the point P2. Conversely, a point P3is said to be “radially outside” a point P4(or “radially on the outside” of the point P4) if it is further away from the axis of rotation of the tire than the point P4. Progress will be said to be “radially inwards (or outwards)” when it is in the direction of the smaller (or larger) radii. This sense of the term also applies when it is a matter of radial distances. In addition, the radius Rx from a point X of the tire is the radial distance between the axis of rotation of said tire and the point X.

Conversely, a thread or a reinforcement is said to be “radial” when the thread or the reinforcing elements of the reinforcement make an angle greater than or equal to 80° and less than or equal to 90° with the circumferential direction. Note that, in this document, the term “thread” should be understood in a very general sense and comprises threads in the form of monofilaments, multifilaments, a cord, a folded yarn or an equivalent assembly, irrespective of the material making up the thread or the surface treatment promoting its bonding with the rubber.

Finally, a “radial cross section” or “radial section” means here a cross section or a section in a plane that contains the axis of rotation of the tire. A “radial or meridian plane” is a plane that contains the axis of rotation of the tire.

An “axial” direction is a direction parallel to the axis of rotation of the tire. A point P5is said to be “axially inside” a point P6(or “axially on the inside” of the point P6) if it is closer to the median plane of the tire than the point P6. Conversely, a point P7is said to be “axially outside” a point P8(or “axially on the outside” of the point P8) if it is further away from the median plane of the tire than the point P8.

The “median plane or equatorial plane” of the tire is the plane that is perpendicular to the axis of rotation of the tire and is equidistant from the annular reinforcing structures of each bead. This plane divides the tire into two substantially equal halves, i.e. passes through the middle of the tread.

A “circumferential direction” is a direction that is perpendicular both to a radius of the tire and to the axial direction. This corresponds to the direction in which the tire runs.

A “circumferential cross section” or “circumferential section” is respectively a cross section or a section in a plane perpendicular to the axis of rotation of the tire. A “circumferential plane” is a plane perpendicular to the axis of rotation of the tire.

The camber angle with the ground is defined on a meridian section through the tire as the angle formed by the equatorial plane of the tire with the direction perpendicular to the ground passing through the point of contact between the tire and the ground. A zero camber angle corresponds to a position in which the tire is perpendicular to the ground, i.e. the perpendicular to the ground is in the equatorial plane of the tire. By extension, the camber angle on the tire is defined on a meridian section through the tire as the angle formed between the equatorial plane of the tire and the direction perpendicular to the direction tangent to the surface of the tire passing through the rolling point of the tire that is intended to be in contact with the ground for a given camber, i.e. the point passing through the rolling line of the tire for a given camber.

In order to make the description of the variants shown in the figures easier to read, the same references are used to denote identical structural elements.

FIG.1is a section through a tire1for a two-wheeled motorized vehicle, of the motorcycle type, comprising a tread2that is connected by two sidewalls3to two beads4.

Each bead4comprises a circumferential reinforcing bead wire5, the beads4being intended to come into contact with a rim on which the tire1is intended to be mounted.

It should be noted that the tire1also generally comprises a carcass structure (not shown), this carcass structure comprising one or more carcass plies that are specifically arranged.

The tire1also comprises, according to the invention, an indicator system6that is made up of a plurality of cavities61formed on the surface of the tread1. As will be seen below, this indicator system (6) can be used to provide information on the camber of the tire and/or on the running-in of the tire.

The cavities61are preferably arranged so as to be distributed over the entire circumference of the tire, and a certain tread width.

More specifically, the cavities61are arranged in a plurality of circumferential sets of cavities (6a;6b;6c) that represent different camber angles of the tire1.

A circumferential set of cavities (6a;6b;6c) comprises a plurality of cavities61that are arranged in a circular arc, preferably in a circle corresponding to a circumferential direction of the tire, in which two adjacent cavities are spaced apart along the circular arc by a circumferential pitch (Pc), this circumferential pitch (Pc) being non-zero.

The circumferential pitch (Pc) is for example between 1 mm and 10 mm, preferably between 1 mm and 8 mm, more preferably between 4 mm and 6 mm. The circumferential pitch (Pc) is for example of the order of 5 mm.

Furthermore, according to the proposed indicator system6, the various circumferential sets of cavities (6a;6b;6c) are arranged in a specific radial pattern, the radial pattern being defined by a radial pitch (Pr) that corresponds to the spacing in the radial direction between the circular arcs of two adjacent circumferential sets of cavities, the radial pitch (Pr) being for example between 1 mm and 10 mm.

More preferably, the radial pitch (Pr) is between 1 mm and 5 mm, and preferentially between 2 mm and 3 mm. The radial pitch (Pr) is for example of the order of 2.5 mm.

The fact of having circumferential sets of cavities (6a;6b;6c) arranged in a specific radial pattern makes it possible to give valuable information to the driver on the use of the tread of the tire used. In particular, the wear of the cavities61enables the driver to know whether or not a particular rolling line, which is at a particular tire camber angle, is sufficiently run in. This also naturally provides information on the use of the tire at a particular camber angle.

The radial pattern can for example be provided so that two adjacent circumferential sets of cavities (6a;6b;6c) are separated radially by an angular camber sector of 1°. Thus, this makes it possible to precisely mark the camber angles on the tire and to give the driver information that is easy to integrate.

The fact that the cavities61are distributed circumferentially allows the driver to obtain information on the camber angle, and therefore on the use of the tire along the corresponding rolling line, regardless of the positioning of the tire with respect to the vehicle.

The fact of providing real cavities61for forming the proposed indicator system6has the advantage of increasing the grip of the tire, in particular when the cavities61are positioned in the running direction. Specifically, the cavities61make it possible to increase the edge ratio, and this in fact increases the grip of the tire.

Each cavity61therefore has minimum dimensions, for example an average width and a depth of at least 0.1 mm, respectively. The average width and the depth are preferably at least 0.2 mm, respectively.

Each cavity61preferably has a maximum average width of less than 3 mm and more preferentially less than 1 mm.

Each cavity61also preferably has a maximum depth of less than 1 mm.

Even more preferably, each cavity61has an average width and/or a maximum depth of between 0.1 mm and 1 mm, and preferably between 0.2 mm and 0.5 mm.

The cavities61of the various circumferential sets of cavities (6a;6b;6c) may have an identical shape and identical dimensions.

However, according to another possible embodiment, the cavities61of two adjacent circumferential sets of cavities (6a;6b;6c) have different depths.

The depth and/or the average width of the cavities61of the circumferential sets of cavities (6a;6b;6c) can for example increase with the corresponding positioning of the tire camber angle. Such an arrangement is particularly advantageous since it makes it possible to vary the edge ratio, and therefore the grip, depending on the camber angle. In particular, it may be appropriate to have a greater edge ratio depending on whether the camber angle is high, since it is in particular in these situations of high camber angle that the driver needs to be reassured about the grip of his or her tire during the running-in phase.

According to a specific example, the depth and/or the average width of the cavities61of the circumferential sets of cavities (6a;6b;6c) increase with the corresponding positioning of the tire camber angle, from a value of 0.2 mm to a value of 1 mm, and preferably from a value of 0.2 mm to a value of 0.5 mm.

Each cavity61is a blind hole having a section with a shape chosen, for example, from among a circular section, a polygonal section, a star-shaped section, and an oval section. This section can vary or be constant depending on the depth of the cavity61.

The exemplary cavity61illustrated inFIG.2corresponds to a cavity61of partially spherical shape, close to a hemisphere.

The radial pattern of the circumferential sets of cavities (6a;6b;6c) forming the indicator system6can be varied.

The circumferential sets of cavities (6a;6b;6c) of the indicator system (6) can be distributed over the tread2of the tire1on either side of the equatorial plane of the tire1in an angular camber region over an angular camber sector of at least 10°, preferably over an angular camber sector of at least 15°, and more preferably over an angular camber sector of at least 20°.

The various circumferential sets of cavities (6a;6b;6c) of the indicator system (6) can be distributed over the tread2on either side of the equatorial plane of the tire1in an angular camber region between a camber angle on the tire of 0° and a camber angle on the tire of at least 40°.

As shown inFIG.3, the circumferential sets of cavities (6a;6b;6c) can are preferably distributed over the entire tread2of the tire1. This makes it possible to have a precise indication of the camber adopted by the tire over the whole tread.

The running-in of a tire is, however, relatively quick and not very risky in terms of grip with regard to the central region of the tread that is positioned on either side of the equatorial plane of the tire. This is less true for the regions of the tread in the shoulder region, i.e. close to the join with the sidewall of the tire. This is because these regions correspond to these high camber angles and therefore regions of the tire that are much less highly stressed. In addition, they correspond to regions in which the risk of loss of grip is increased and in which the tire absolutely has to play its role in order to ensure the required grip.

Thus, it could be provided to distribute the circumferential sets of cavities (6a;6b;6c) over the tread2of the tire1only in the shoulder regions, for example an angular camber region between a camber angle on the tire of 30° and a camber angle on the tire of 60°.

Preferably, the circumferential sets of cavities (6a;6b;6c) are distributed over an angular camber region between a camber angle on the tire of 40° and a camber angle on the tire of 58°, and more preferably between a camber angle on the tire of 48° and a camber angle on the tire of 58°.

FIGS.4to6illustrate such an arrangement in the shoulder region according to a first specific exemplary embodiment in which the cavities61are distributed between a camber angle on the tire (α1) of approximately 40° and a camber angle on the tire (α2) of approximately 58°.

The indicator system6according to this first exemplary embodiment comprises17circumferential sets of cavities, in which two adjacent circumferential sets of cavities are spaced apart by a camber angle of approximately 1°. The corresponding radial pitch (Pr) is of the order of 2.5 mm.

According to this first exemplary embodiment, the cavities61have a shape corresponding to a portion of a sphere, with a maximum width of approximately 1.5 mm at the surface of the tread (i.e. a radius of 0.75 mm) and a variable depth between the two extreme positions of the shoulder region, of between 0.2 mm on the side of the centre of the tire and 0.5 mm on the side of the sidewall. The circumferential pitch (Pc) between two cavities61of a single circumferential set of cavities is, according to this example, of the order of 5 mm.

As is apparent inFIG.5, the adjacent cavities61of two adjacent circumferential sets of cavities (6a;6b;6c) are offset, not aligned in one and the same radial direction.

It could however be provided that the indicator system6is formed such that the adjacent cavities61of two adjacent circumferential sets of cavities (6a;6b;6c) are aligned in one and the same radial direction.

FIGS.7and8illustrate an arrangement in the shoulder region according to a second specific exemplary embodiment in which the cavities61are distributed between a camber angle on the tire (β1) of approximately 48° and a camber angle on the tire (β2) of approximately 58°.

The indicator system6according to this second exemplary embodiment comprises 10 circumferential sets of cavities, in which two adjacent circumferential sets of cavities are spaced apart by a camber angle of approximately 1°. The corresponding radial pitch (Pr) is of the order of 1.2 mm.

According to this second exemplary embodiment, the cavities61also have a substantially hemispherical shape, with a width of approximately 1.5 mm (i.e. a circular section at the surface of the tread having a radius of 0.75 mm) and a variable depth between the two ends of the positioning shoulder region, of between 0.2 mm and 0.5 mm on the side of the sidewall. The circumferential pitch (Pc) between two cavities61of a single circumferential set of cavities is, according to this example, also of the order of 2.5 mm.

The tire presented here can advantageously have a tread2further comprising a plurality of substantially longitudinal notches71positioned on either side of the equatorial plane of the tire1. These notches can have a role of evacuating water throughout the duration of the use of the tire and therefore well beyond the running-in phase.

Such an arrangement of longitudinal notches71complementing the proposed indicator system is particularly advantageous when the cavities61of the indicator system6are only positioned on the shoulder regions of the tire, since these notches71improve the grip of the tire in the equatorial region during the running-in phase.

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.