A tire including a pair of transverse notches for sound dispersion

Abstract

The present invention relates to a tire (10) including transverse notches (80, 90) arranged in axial transverse portions (P1, P2). The transverse notches (80, 90) arranged in each axial transverse portion (P1, P2) include at least one sound dispersion pair of first and second transverse notches (801, 802, 811, 812). Each axial inner portion (861, 862, 871, 872) of each first and second transverse notches (801, 802, 811, 812) of the sound dispersion pair extends in an average direction forming a first non-zero average angle with the axial direction (Y) different from a second non-zero average angle (F1, F2, F11, F12) with the axial direction (Y).

Description

Technical Field

[0001] The present invention relates to a tire for a passenger car. The tire is understood to be a casing intended to form a cavity by cooperating with a support element, such as a rim, which cavity can be pressurized up to a pressure higher than atmospheric pressure. The tire according to the invention has a substantially toroidal structure showing rotational symmetry around the main axis of the tire.

Background Art

[0002] Tires for passenger cars sold within the PRIMACY 4 (registered trademark) series under the MICHELIN (registered trademark) brand name are known from the prior art. Such tires include a tread intended to come into contact with the ground through the tread surface when the tire is in motion.

[0003] The tread has a depth of more than 50% of the tread pattern height and includes main circumferential cuts including first and second axially outer main circumferential cuts on both sides of the meridian plane of the tire. The first and second axially outer main circumferential cuts are the axially outermost main circumferential cuts of the tread.

[0004] The tread includes a first axially transverse portion axially outside the first axially outer main circumferential cut and a second axially transverse portion axially outside the second axially outer main circumferential cut. The tread also includes transverse cuts partially formed in each of the first and second axially transverse portions.

[0005] Due to increasingly strict regulations on the external noise generated by tires, tires of the prior art generate external noise that is reduced as much as possible not only under normal use conditions but also under use conditions far from normal use conditions. The use conditions are understood to mean conditions related not only to the speed, pressure, and load of the tire, but also to the width of the rim on which the tire is mounted.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The object of the present invention is thus to reduce the external noise generated by the tire by reducing the noise generated by the transverse cuts formed in the first and second axial lateral portions under a very wide range of operating conditions.

Means for Solving the Problems

[0007] For this purpose, the present invention relates to a tire for a passenger car including a tread intended to contact the ground through the tread surface when the tire is running, the tread comprising: · first and second axially outer main circumferential cuts which are arranged on both axial sides of the axis of the meridian plane of the tire and are the axially outermost main circumferential cuts of the tread, and which have a depth of 50% or more of the tread pattern height; and · a first axially lateral portion which is arranged axially outside the first axially outer main circumferential cut and extends axially from the first axial edge of the tread surface to the axial outer edge of the first axially outer main circumferential cut; and · a second axially lateral portion which is arranged axially outside the second axially outer main circumferential cut and extends axially from the second axial edge of the tread surface to the axial outer edge of the second axially outer main circumferential cut; and including the tread includes at least a transverse cut partially formed in at least one of the first and second axially lateral portions, at least one of the first and second axially lateral portions has an axial width equal to 50% of the axial width of at least one of the first and second axially lateral portions and includes an axial portion extending axially outward from the axial outer edge of the first or second axially outer main circumferential cut from which at least one of the first and second axially lateral portions extends, each transverse cut includes an axially inner portion extending within the axial portion of at least one of the first and second axially lateral portions, The transverse cut formed in at least one of the first and second axial lateral portions includes at least one sound dispersion pair including the first and second transverse cuts, and each axial inner portion of each of the first and second transverse cuts of the sound dispersion pair is, respectively, · When La1 > 1.5 mm and La2 > 1.5 mm, 1 ≤ La1 / La2 ≤ 2.5, · When La1 > 1.5 mm and La2 ≤ 1.5 mm, 1 ≤ La1 / La2 ≤ 3.0, · When La1 ≤ 1.5 mm, 1 ≤ La1 / La2 ≤ 4.0, having widths La1, La2 such that, each axial inner portion of each of the first and second transverse cuts of the above or each sound dispersion pair extends in an overall direction forming a first and second non-zero average angle with the axial direction, the first average angle of the axial inner portion of the first transverse cut of the above or each sound dispersion pair is different from the second average angle of the axial inner portion of the second transverse cut of the sound dispersion pair.

[0008] The present invention makes it possible to reduce external noise generated by a transverse cut formed in at least one of the first and second axial lateral portions under a very wide range of use conditions. In other words, the tire according to the present invention has a considerable multifunctionality in terms of its performance regarding external noise.

[0009] Specifically, the inventor who carried out the present invention found that the external noise generated by the transverse cut becomes increasingly large when the edge of the transverse cut coincides with the edge of the tire's ground contact surface.

[0010] The shape of the ground contact surface and thus its edges depends on the operating conditions. As a result, under some operating conditions, the circumferential grooves of a given tire coincide to a significant extent with the edges of the tire's ground contact surface and thus may generate relatively high external noise. On the other hand, under other operating conditions, the circumferential grooves of this same tire coincide only slightly or not at all with the edges of the tire's ground contact surface, i.e., they may generate relatively quiet external noise. Providing circumferential grooves with different average angles in the axial direction reduces the occurrence of coincidence between the edge corners of the circumferential grooves and the edges of the tire's ground contact surface and thus the external noise generated by the tire, regardless of the operating conditions.

[0011] This describes circumferential groove pairs and the sound dispersion function associated with each of their parts that make it possible to disperse the noise generated by the circumferential grooves under a very wide range of operating conditions.

[0012] Each of the axially inner parts of the first and second circumferential grooves of the sound dispersion pair respectively has · When La1 > 1.5 mm and La2 > 1.5 mm, 1 ≤ La1 / La2 ≤ 2.5, · When La1 > 1.5 mm and La2 ≤ 1.5 mm, 1 ≤ La1 / La2 ≤ 3.0, · When La1 ≤ 1.5 mm, 1 ≤ La1 / La2 ≤ 4.0, characteristics such that widths La1, La2 having this result enable consideration of circumferential grooves having equal lengths and thus equivalent behavior even if the grooves do not have exactly the same width.

[0013] In the deformation, it may be assumed that the axially inner part does not reach into one of the adjacent first and second axially outer main circumferential cuts. In these deformations, the transverse cut is called a blind. In other deformations, the axially inner part reaches into one of the adjacent first and second axially outer main circumferential cuts. The mobility of the tread pattern is thus promoted compared to the case of a blind transverse cut, thereby improving the flattening of the tire and consequently the rolling resistance.

[0014] Conventionally, the tread surface is axially delimited by the first and second axially edges. The first and second axially edges of the tread surface are determined for a tire mounted on a nominal rim and inflated to the nominal pressure in accordance with the European Tyre and Rim Technical Organization or "ETRTO" standard (2021). The first and second axially edges of the tread surface are arranged on both sides of the meridian plane of the tire and are formed by lines substantially parallel to the circumferential direction of the tire. When there is a clear boundary between the tread surface and the rest of the tire, the first and second axially edges of the tread surface are easily determined. When the tread surface is continuous with the outer surface of the sidewall of the tire, the first and second axially edges can be determined taking into account that each first and second axially edge passes through a point in each meridian section, and at this point, the angle between the tangent of the tread surface and a straight line parallel to the axial direction passing through this point is equal to 30°. When there are several points in the meridian section where this angle is equal to 30° in absolute value, the radially outermost point is used.

[0015] The average angle of a part is determined by taking a straight line extending between two end points of this part, the two end points being located at the ends of each part and being equidistant from the leading and trailing edges of each end of this part.

[0016] Of course, the transverse cuts, in particular the first, second, and optionally third transverse cuts for sound dispersion, are separate from each other. As a result, the transverse cuts, in particular the first, second, and optionally third transverse cuts for sound dispersion, are offset from each other in the circumferential direction. Therefore, there is no direct axial communication between the transverse cuts, in particular the first, second, and optionally third transverse cuts for sound wave dispersion. As a result, there is no communication between the transverse cuts, in particular the first, second, and optionally third transverse cuts for sound dispersion, or if there is communication between them, it is either through a cut that is not a transverse cut, for example, a circumferential cut. The transverse cuts, in particular the first, second, and optionally third transverse cuts for sound dispersion, are not axially continuous with each other, that is.

[0017] The above or each first and second axial transverse portions of the tread can of course also include other transverse cuts that do not have the characteristics of the transverse cuts according to the present invention, in particular the characteristics regarding the width of their axially inner portions, and circumferential cuts having a depth of strictly less than 50% of the tread pattern height.

[0018] The cut or cut portion has two main characteristic dimensions on the tread surface, namely, a width and a curved length such that the curved length is at least equal to twice the width. The cut or cut portion is thus delimited by at least two main transverse surfaces that determine its curved length and are connected by a bottom, and the two main transverse surfaces are separated from each other by a non-zero distance called the width of the cut or cut portion.

[0019] For a new tire, the width of the cut or cut portion is the maximum distance between two major transverse planes measured at the radial point that coincides with the tread surface when the cut or cut portion is default and not chamfered, and measured at the outermost radial point of the cut or cut portion and inside the radial of the chamfer portion when the cut or cut portion is default and chamfered. This width is measured substantially perpendicular to the major transverse plane. When a width other than the default width, for example, the width at a specific point is specified, the width is equal to the distance between two major transverse planes at the specific point of the cut or cut portion.

[0020] For a new tire, the depth of the cut or cut portion is the maximum radial distance between the bottom of the cut or cut portion and its projection onto the ground when the tire is in motion. The maximum value for the depth of the cut is called the tread pattern height.

[0021] The cut or cut portion can be in the transverse direction or the circumferential direction.

[0022] A transverse cut is one in which the cut forms an angle with the circumferential direction of the tire that is strictly greater than 30°, preferably 45° or more, i.e., forms an angle with the axial direction of the tire that is 60° or less, preferably strictly less than 45°. The overall direction is the shortest curve that joins the two ends of the cut and is parallel to the tread surface. The transverse cut or portion can be continuous, i.e., not interrupted by a tread pattern block or another cut so that the two major transverse planes that define its length are not interrupted over the length of the transverse cut or portion. The transverse cut can likewise be discontinuous, i.e., interrupted by one or more tread pattern blocks and / or one or more cuts so that the two major transverse planes that define its length are interrupted by one or more tread pattern blocks and / or one or more cuts.

[0023] A circumferential cut is one in which the cut or portion forms an angle of 30° or less, preferably 10° or less, with the circumferential direction of the tire, i.e., forms an angle strictly greater than 60°, preferably strictly greater than 80°, with the axial direction of the tire, and extends in an overall direction. The overall direction is the shortest curve that joins the two ends of the cut and is parallel to the tread surface. In the case of a continuous circumferential cut, the two ends coincide with each other and are joined by a curve that goes around the tire. The circumferential cut can be continuous, i.e., not interrupted by a tread pattern block or another cut so that the two main transverse planes that define its length go around the tire without interruption. The circumferential cut can likewise be discontinuous, i.e., interrupted by one or more tread pattern blocks and / or one or more other cuts so that the two main transverse planes that define its length are interrupted by one or more tread pattern blocks and / or one or more other cuts across the entire circumference of the tire.

[0024] In the case of a transverse cut or a transverse cut portion, the transverse plane is called the front face and the rear face, and each is provided with a leading edge and a trailing edge respectively. The leading edge is the edge that enters the ground contact surface in front of the trailing edge with respect to a given circumferential line.

[0025] In an embodiment for optionally improving braking on a dry ground, the above or each transverse cut is chamfered. The chamfer for the transverse cut can be a corner chamfer or a round chamfer. The corner chamfer is formed by a flat surface inclined with respect to the front face and the rear face continuing far to the leading edge or the trailing edge that circumferentially delimits the transverse cut. The round chamfer is formed by a curved surface tangentially merging into the front face or the rear face continuing. The chamfer of the transverse cut is characterized by a height and a width respectively equal to the radial distance between the points common to the chamfered front face or rear face and the leading edge or the trailing edge that circumferentially delimits the transverse cut, and the distance in the direction perpendicular to the front face or the rear face.

[0026] In some embodiments, to improve braking on arbitrarily wet ground and lateral grip on dry ground, at least one of the main circumferential grooves is chamfered. The chamfering of the circumferential groove can be a chamfer or a round chamfer. The chamfer is formed by a flat surface inclined with respect to the axial inner surface and the outer surface continuously extending far to the axial inner edge or the outer edge that axially delimits the circumferential groove. The round chamfer is formed by a curved surface tangentially merging into the axial inner surface or the outer surface continuously extending. The chamfering of the circumferential groove is characterized by a height and a width respectively equal to the radial distance and the axial distance between the common points of the axially extended inner surface or outer surface with the chamfer and the axial inner edge or outer edge that axially delimits the circumferential groove.

[0027] The tire according to the present invention has a substantially annular shape centered on a turning axis that substantially coincides with the rotation axis of the tire. This turning axis defines the three directions conventionally used by those skilled in the art, namely, the axial direction, the circumferential direction, and the radial direction.

[0028] The expression "axial direction" means a direction substantially parallel to the turning axis of the tire, that is, the rotation axis of the tire.

[0029] The expression "circumferential direction" means a direction substantially perpendicular to both the axial direction and the radius of the tire (in other words, tangent to the circle centered on the rotation axis of the tire).

[0030] The expression "radial direction" means a direction along the radius of the tire, that is, any direction intersecting the rotation axis of the tire and substantially perpendicular to that axis.

[0031] The meridian plane of the tire (denoted by M) is understood to be a plane perpendicular to the rotation axis of the tire located at the axial midpoint between the two beads and passing through the axial center of the crown reinforcement.

[0032] The expression "equatorial circumferential plane of the tire" (denoted by E) means a plane passing through the equator of the tire that is perpendicular to the meridian plane and the radial direction within the meridian cross-section. The equator of the tire is an axis parallel to the rotation axis of the tire within the meridian cross-section (a plane perpendicular to the circumferential direction and parallel to the radial direction and the axial direction), and is an axis located equidistantly between the radially outermost point of the tread intended to contact the ground and the radially innermost point of the tire intended to contact a support, for example, a rim. The distance between these two points is equal to H.

[0033] The expression "meridian plane" means a plane parallel to and containing the rotation axis of the tire and perpendicular to the circumferential direction.

[0034] The expressions "radially inside / towards the inside in the radial direction" and "radially outside / towards the outside in the radial direction" respectively mean "closer to the rotation axis of the tire" and "farther from the rotation axis of the tire". The expressions "axially inside / towards the inside in the axial direction" and "axially outside / towards the outside in the axial direction" respectively mean "closer to the meridian plane of the tire" and "farther from the meridian plane of the tire".

[0035] The bead is understood to be the part of the tire intended to enable the tire to be attached to a support, for example, a wheel having a rim. That is, each bead is intended to contact, in particular, the flange of the rim that enables the tire to be attached.

[0036] Any range of values indicated by the expression "between a and b" represents a range of values extending from greater than a to less than b (i.e., excluding the endpoints a and b), while any range of values indicated by the expression "from a to b" means a range of values extending from a to b (i.e., including the exact endpoints a and b).

[0037] In a preferred embodiment of the present invention, the tire is intended for a passenger car defined in accordance with the European Tyre and Rim Technical Organization, i.e., the "ETRTO" standard (2021). Such a tire has a cross-section in the meridian plane characterized by a section height H and a nominal section width S in the sense of the European Tyre and Rim Technical Organization, i.e., the "ETRTO" standard (2021), where the ratio H / S expressed as a percentage is at most equal to 90, preferably at most equal to 70 and at least equal to 30, the nominal section width S is at least equal to 115 mm, preferably at least equal to 175 mm, and at most equal to 385 mm, preferably at most equal to 315 mm. Further, the flange diameter D defining the diameter of the rim on which the tire is mounted is at least equal to 12 inches, preferably at least equal to 16 inches, and at most equal to 24 inches.

[0038] In a preferred embodiment of the present invention, the tire is a "summer" tire. A summer tire is understood to be a tire that is neither a "4-season" tire nor an "all-season" tire nor a "winter" tire.

[0039] Winter tires are identified in particular by the M+S marking (M+S is an abbreviation for "Mud + Snow") and / or the 3PMSF marking (3PMSF is an abbreviation for "3 Peak Mountain Snow Flake"). 4-season tires or all-season tires also have the M+S and / or 3PMSF marking for snow performance. That is, summer tires have neither the M+S marking nor the 3PMSF marking.

[0040] The tread optimally but optionally includes at least transverse cuts formed in each of the first and second axially lateral portions. Each of the first and second axial-direction transverse portions has an axial-direction width equal to 50% of the axial-direction width of each of the first and second axial-direction transverse portions, respectively, and includes an axial-direction portion extending axially outward from the axial-direction inner edge of each of the first or second axial-direction outer main circumferential-direction cuts. From the axial-direction inner edge, each of the first and second axial-direction transverse portions extends, Each transverse-direction cut includes an axially inner portion extending within the axial-direction portion of the first and second axial-direction transverse portions, The transverse-direction cut formed in the first axial-direction transverse portion includes at least one first sound dispersion pair including the first and second transverse-direction cuts, and the transverse-direction cut formed in the second axial-direction transverse portion includes at least one second sound dispersion pair including the first and second transverse-direction cuts, Each axially inner portion of each of the first and second transverse-direction cuts of each of the first and second sound dispersion pairs is, respectively, · When La1 > 1.5 mm and La2 > 1.5 mm, 1 ≤ La1 / La2 ≤ 2.5, · When La1 > 1.5 mm and La2 ≤ 1.5 mm, 1 ≤ La1 / La2 ≤ 3.0, · When La1 ≤ 1.5 mm, 1 ≤ La1 / La2 ≤ 4.0, and has widths La1, La2 such that, Each axially inner portion of each of the first and second transverse-direction cuts of each of the first and second sound dispersion pairs extends in an overall direction forming a first and second non-zero average angle with the axial direction, The first average angle of the axially inner portion of the first transverse-direction cut of each of the first and second sound dispersion pairs is different from the second average angle of the axially inner portion of the second transverse-direction cut of each of the first and second dispersion pairs.

[0041] In a preferred embodiment, each axially inner portion of each of the first and second transverse-direction cuts of the sound dispersion pair is, respectively, · When La1 > 1.5 mm and La2 > 1.5 mm, 1 ≤ La1 / La2 ≤ 2.1, · When La1 > 1.5 mm and La2 ≤ 1.5 mm, 1 ≤ La1 / La2 ≤ 2.4, ·When La1 ≦ 1.5 mm, 1 ≦ La1 / La2 ≦ 3.2, having widths La1 and La2 such that...

[0042] In an advantageous embodiment, the axially inner portions of the first and second transverse cuts of the above or each sound dispersion pair have a width in the range of 0.2 mm to 2.2 mm, preferably 0.2 mm to 1.0 mm, more preferably 0.2 mm to 0.6 mm, and even more preferably 0.2 mm to 0.5 mm. By limiting the width of the axially extending portion, the noise generated by the sound dispersion cuts can be limited.

[0043] In an advantageous embodiment, the axially inner portions of the first and second transverse cuts of the above or each sound dispersion pair have a depth in the range of 2.0 mm to 5.5 mm, preferably in the range of 3.0 mm to 5.0 mm.

[0044] Optionally and preferably, each main circumferential cut has a depth of 75% or more, more preferably 90% or more of the tread pattern height.

[0045] In embodiments where the main circumferential cuts are relatively deep, each main circumferential cut has a depth in the range of 4.0 mm to the tread pattern height, preferably in the range of 5.0 mm to the tread pattern height, more preferably in the range of 5.5 mm to the tread pattern height.

[0046] In embodiments where the main circumferential cuts are relatively wide main circumferential grooves, each main circumferential cut has an axial width of 1.0 mm or more, preferably 5.0 mm or more, more preferably in the range of 5.0 mm to 20.0 mm.

[0047] In an optional embodiment, it is also conceivable that at least one of the first and second axially extending portions includes at least one additional circumferential cut having a depth of strictly less than 50% of the tread pattern height, preferably 30% or less of the tread pattern height, more preferably in the range of 10% to 30% of the tread pattern height.

[0048] For each first and second non-zero average angles of the axially inner portions of the above or each sound dispersion pair of each first and second transverse cuts, optionally but preferably, they are 50° or less, preferably 40° or less, and more preferably in the range of 5° to 40°.

[0049] When the average angle is excessively small, there is a high risk that the edge corner of the transverse cut for sound dispersion coincides with the edge of the tire's ground contact surface under most usage conditions, and thus the noise generated by the tire increases. Conversely, when the average angle is excessively large, the risk of the tire being pulled increases, that is, the risk of a force being generated in the axial direction of the tire increases.

[0050] In some embodiments, the absolute value difference between the first average angle and the second average angle of the above or each sound dispersion pair is 40° or less, preferably 30° or less. Although the usage conditions of the tire can be significantly different, it is still considered an exceptional case that the usage conditions are so different that an excessive deviation needs to be provided between the angle values.

[0051] In still other embodiments, the absolute value difference between the first average angle and the second average angle of the above or each sound dispersion pair is 5° or more, preferably 10° or more. Conversely, the more the value of the deviation between the angles increases significantly, the more likely the conditions for reducing noise will be different.

[0052] In embodiments where the present invention is applied to a significant number of transverse cuts of the above or each first and second axially transverse portions, and the first and second average angles are equal to values taken from at least a list of first and second different values, · The average angle of at least 25%, preferably at least 50%, more preferably at least 75% of the axially inner portion of the transverse cut of at least one of the first and second axially transverse portions is equal to at least one of the first and second different values, · Each axially inner portion of each transverse cut whose average angle is equal to at least one of the first and second different values is · When Lamax > 1.5 mm and La > 1.5 mm, 1 ≤ Lamax / La ≤ 2.5, preferably 1 ≤ Lamax / La ≤ 2.1, · When Lamax > 1.5 mm and La ≤ 1.5 mm, 1 ≤ Lamax / La ≤ 3.0, preferably 1 ≤ Lamax / La ≤ 2.4, · When Lamax ≤ 1.5 mm, 1 ≤ Lamax / La ≤ 4.0, preferably 1 ≤ Lamax / La ≤ 3.2, having a width La such that, where Lamax is the maximum value of the width of the axial inner portion of at least 25%, preferably at least 50%, more preferably at least 75% of the transverse cuts whose average angle is equal to at least one of the first and second different values.

[0053] That is, by increasing the number of pairs of transverse cuts having different average angles, the dispersion of noise under different usage conditions is promoted.

[0054] In these embodiments, it is advantageous in the following cases: · The average angle of at least 15%, preferably at least 25% of the axial inner portion of the transverse cuts of at least one of the first and second axial transverse portions is equal to the first value, and · The average angle of at least 15%, preferably at least 25% of the axial inner portion of the transverse cuts of at least one of the first and second axial transverse portions is equal to the second value.

[0055] As a result, it is guaranteed that a significant number of transverse cuts have an average angle value equal to one of the first and second values, and that a significant number of transverse cuts reach each of the first and second values with respect to the total number of transverse cuts of the above or each of the first and second axial transverse portions.

[0056] In an optional embodiment for more advantageously dispersing noise, the transverse cuts at least partially formed in at least one of the first and second axial transverse portions include at least one sound dispersion trio including first, second, and third transverse cuts, each of the first, second, and third transverse cuts of the above or each sound dispersion trio includes an axially inner portion extending within an axial portion of at least one of the first and second axial transverse portions, each axially inner portion of each of the first, second, and third transverse cuts of the sound dispersion trio respectively, · when La1>1.5mm and La3>1.5mm, 1≦La1 / La3≦2.5, preferably 1≦La1 / La3≦2.1, · when La1>1.5mm and La3≦1.5mm, 1≦La1 / La3≦3.0, preferably 1≦La1 / La3≦2.4, · when La1≦1.5mm, 1≦La1 / La3≦4.0, preferably 1≦La1 / La3≦3.2, has widths La1≧La2≧La3 such that, each axially inner portion of each of the first, second, and third transverse cuts of the above or each sound dispersion trio respectively extends in an overall direction forming non-zero average angles with the axial direction and the first, second, and third, the first, second, and third average angles of the axially inner portions of the first, second, and third transverse cuts of the above or each sound dispersion trio are different in pair units.

[0057] In other words, the first average angle is different from the second average angle, the second average angle is different from the third average angle, and the first average angle is different from the third average angle.

[0058] By taking three average angle values, more usage conditions for substantially dispersing noise are considered. In the case of a mold including a plurality of different patterns, it is advantageous to select the number of average angles equal to the number of different patterns to limit the complexity of the mold design and make each pattern correspond to only one average angle.

[0059] Similar to what is optionally given to the pair of transverse cuts, each of the first, second, and third non-zero average angles of the axially inner portions of the above or each sound dispersion trio's first, second, and third transverse cuts is 50° or less, preferably 40° or less, and more preferably in the range of 5° to 40°.

[0060] Similar to what is optionally given to the pair of transverse cuts, · the first average angle and the second average angle of the above or each sound dispersion trio, · the second average angle and the third average angle of the above or each sound dispersion trio, · the first average angle and the third average angle of the above or each sound dispersion trio, each difference in absolute value between them is 40° or less, preferably 30° or less, and / or 5° or more, preferably 10° or more.

[0061] Similar to what is optionally given to the pair of transverse cuts, the first, second, and third average angles are equal to values taken from a list of at least the first, second, and third different values in pair units: · the average angle of at least 25%, preferably at least 50%, more preferably at least 75% of the axially inner portion of at least one of the first and second axially transverse portions' transverse cuts is equal to at least one of the first, second, and third different values, · each axially inner portion of each transverse cut whose average angle is equal to at least one of the first, second, and third different values · when Lamax > 1.5 mm and La > 1.5 mm, 1 ≦ Lamax / La ≦ 2.5, preferably 1 ≦ Lamax / La ≦ 2.1, · when Lamax > 1.5 mm and La ≦ 1.5 mm, 1 ≦ Lamax / La ≦ 3.0, preferably 1 ≦ Lamax / La ≦ 2.4, · when Lamax ≦ 1.5 mm, 1 ≦ Lamax / La ≦ 4.0, preferably 1 ≦ Lamax / La ≦ 3.2, having a width La as described, where Lamax is the maximum value of the width of at least 25%, preferably at least 50%, more preferably at least 75% of the axial inner portion of the transverse cuts having an average angle equal to one of at least the first, second, and third values that differ in pair units.

[0062] Similar to what is optionally given to the pairs of transverse cuts, · The average angle of at least 15%, preferably at least 25% of the axial inner portion of the transverse cuts of at least one of the first and second axial transverse portions is equal to the first value, · The average angle of at least 15%, preferably at least 25% of the axial inner portion of the transverse cuts of at least one of the first and second axial transverse portions is equal to the second value, · The average angle of at least 15%, preferably at least 25% of the axial inner portion of the transverse cuts of at least one of the first and second axial transverse portions is equal to the third value.

[0063] In some embodiments, the first and second transverse cuts of the above or each sound dispersion pair are adjacent in the circumferential direction.

[0064] This reduces the occurrence of two adjacent transverse cuts in the circumferential direction that generate the same external noise under given use conditions. The dispersion of the noise generated under given use conditions is thus promoted, especially when these given use conditions cause at least a part of the edges of the transverse cuts to coincide with the edges of the tire's contact surface.

[0065] The expression "adjacent in the circumferential direction" means · When La1 > 1.5 mm and La2 > 1.5 mm, 1 ≤ La1 / La2 ≤ 2.5, preferably 1 ≤ La1 / La2 ≤ 2.1, · When La1 > 1.5 mm and La2 ≤ 1.5 mm, 1 ≤ La1 / La2 ≤ 3.0, preferably 1 ≤ La1 / La2 ≤ 2.4, ·When La1 ≤ 1.5 mm, 1 ≤ La1 / La2 ≤ 4.0, preferably 1 ≤ La1 / La2 ≤ 3.2, It means that a transverse cut having an axially inner portion with a width La as such is not circumferentially arranged between the transverse cuts of the sound dispersion pair.

[0066] Similarly, in the case of a trio of circumferentially adjacent transverse cuts, in some embodiments, the first, second, and third transverse cuts of the above or each sound dispersion trio are such that they are circumferentially adjacent.

[0067] The expression "circumferentially adjacent" is the same as for the sound dispersion pair, ·When La1 > 1.5 mm and La2 > 1.5 mm, 1 ≤ La1 / La3 ≤ 2.5, preferably 1 ≤ La1 / La3 ≤ 2.1, ·When La1 > 1.5 mm and La2 ≤ 1.5 mm, 1 ≤ La1 / La3 ≤ 3.0, preferably 1 ≤ La1 / La3 ≤ 2.4, ·When La1 ≤ 1.5 mm, 1 ≤ La1 / La3 ≤ 4.0, preferably 1 ≤ La1 / La3 ≤ 3.2, It means that a transverse cut having an axially inner portion with a width La as such is not circumferentially arranged between the transverse cuts of the sound dispersion trio.

[0068] The absolute value of the difference between the first average angle and the second average angle of the above or each sound dispersion pair of the first and second circumferentially adjacent transverse cuts is optionally but preferably 20° or less.

[0069] This is because when axially oriented portions having overly different average angles belong to circumferentially adjacent transverse cuts for sound dispersion, the difference in stiffness between adjacent blocks of rubber becomes overly large, thereby potentially causing non-uniform wear. In this case, limiting the difference between these average angles reduces the difference in stiffness between adjacent blocks of rubber, thereby promoting uniform wear of the tread.

[0070] The absolute value of the difference between the first and second average angles of the above or each sound dispersion pair of the first and second transverse cuts adjacent in the circumferential direction is optionally but preferably 5° or more, preferably 10° or more.

[0071] By sufficiently differentiating the average angles, the noise generated by adjacent transverse cuts of the tire under sufficiently different usage conditions is reduced.

[0072] Similar to those optionally given to the pair of transverse cuts, the absolute value of the difference between one of the first, second, and third average angles of the above or each sound dispersion trio of the first, second, and third transverse cuts adjacent in the circumferential direction is 20° or less and / or 5° or more, preferably 10° or more.

[0073] In a preferred embodiment, a tread including N circumferentially adjacent transverse cuts forming N pairs of transverse cuts adjacent in the circumferential direction around the tire is used, and the width La of the axially inner portion of each of the N circumferentially adjacent transverse cuts is · When Lamax> 1.5 mm and La> 1.5 mm, 1 ≦ Lamax / La ≦ 2.5, preferably 1 ≦ Lamax / La ≦ 2.1, · When Lamax> 1.5 mm and La ≦ 1.5 mm, 1 ≦ Lamax / La ≦ 3.0, preferably 1 ≦ Lamax / La ≦ 2.4, · When Lamax ≦ 1.5 mm, 1 ≦ Lamax / La ≦ 4.0, preferably 1 ≦ Lamax / La ≦ 3.2, such that, where Lamax is the maximum value of the width of the axially inner portion of the transverse cuts of the N pairs of circumferentially adjacent transverse cuts, and the average angles of the axially inner portions of at least 25%, preferably at least 35% of the N pairs of the N circumferentially adjacent transverse cuts are different.

[0074] In other words, at least 25%, at least 50% of the N pairs of circumferentially adjacent transverse cuts are sound dispersion pairs.

[0075] Similarly, in the case of a trio of circumferentially adjacent transverse cuts, in some embodiments, a tire is used that includes N circumferentially adjacent transverse cuts and N trios of circumferentially adjacent transverse cuts in the circumferential rotation direction around the tire. The width La of the axially inner portion of each of the N circumferentially adjacent transverse cuts is such that · When Lamax > 1.5 mm and Lai > 1.5 mm, 1 ≦ Lamax / La ≦ 2.5, preferably 1 ≦ Lamax / La ≦ 2.1, · When Lamax > 1.5 mm and Lai ≦ 1.5 mm, 1 ≦ Lamax / La ≦ 3.0, preferably 1 ≦ Lamax / La ≦ 2.4, · When Lamax ≦ 1.5 mm, 1 ≦ Lamax / La ≦ 4.0, preferably 1 ≦ Lamax / La ≦ 3.2, where Lamax is the maximum value of the width of the axial portion of the N trios of circumferentially adjacent transverse cuts, and the average angle of the axial portion of at least 15%, preferably at least 20% of the N trios of N circumferentially adjacent transverse cuts is different in pair units.

[0076] In other words, at least 15%, at least 20% of the N pairs of circumferentially adjacent transverse cuts are sound dispersion trios.

[0077] In a preferred embodiment for further improving the uniformity of tread wear, when using a tire that includes a plurality of sound dispersion pairs, each sound dispersion pair including a first and a second transverse cut that are circumferentially adjacent in the circumferential rotation direction around the tire, the absolute value of the difference between the first average angle and the second average angle of at least 25%, preferably at least 50%, more preferably at least 75% of the sound dispersion pairs of the first and second circumferentially adjacent transverse cuts is 20° or less.

[0078] In a preferred variant for further reducing the noise generated by a tire under very different usage conditions, a tire is used which includes a plurality of sound dispersion pairs, each sound dispersion pair including first and second transverse cuts that are circumferentially adjacent in the circumferential rotation direction around the tire, and the absolute value of the difference between the first and second average angles of at least 25%, preferably at least 50%, more preferably at least 75% of the sound dispersion pairs of the first and second transverse cuts that are circumferentially adjacent is 5° or more, preferably 10° or more.

[0079] Similar to what is optionally given to the pairs of transverse cuts, the absolute value of the difference between at least one of the first, second, and third average angles and at least one other of the first, second, and third average angles of at least 25%, preferably at least 50%, more preferably at least 75% of the sound dispersion trios of the first, second, and third transverse cuts that are circumferentially adjacent is 20° or less and / or 5° or more, preferably 10° or more.

[0080] In a preferred but optional embodiment, the axial inner part of each transverse cut of the above or each sound dispersion pair or trio extends along an axial length equal to at least 20%, preferably at least 35% of the axial length of the part formed on at least one of the first and second axial transverse parts of each transverse cut of the acoustic dispersion pair or trio.

[0081] The longer the axial length of the axial part contributing to the dispersion of the noise, the more the noise generated by each transverse cut of each sound dispersion pair or trio is dispersed.

[0082] In some embodiments, the axial inner part does not extend over the entire axial length of at least one of the first and second axial transverse parts. In other embodiments, the axial inner part extends over the entire axial length of at least one of the first and second axial transverse parts.

[0083] Since the tread is intended to contact the ground through the tread surface when the tire is in motion, its curved length is thus determined within the relevant part of the tread and is thus limited to the tread surface and thus to the first and second axial lateral parts.

[0084] The axial length of a transverse cut part or a part of a transverse cut, regardless of whether it belongs to a sound dispersion pair or trio, is the length measured axially along between the two ends of the part of the transverse cut or that part thereof.

[0085] In some deformations, each transverse cut of the above or each sound dispersion pair or trio includes an axially outer part arranged axially outside the axially inner part and communicating with the axially inner part, and the axially outer part is the axially outermost part of each transverse cut of the above or each sound dispersion pair or trio formed in at least one of the first and second axial lateral parts.

[0086] In these deformations, preferably, the axially outer part of each transverse cut of the above or each sound dispersion pair or trio extends in an overall direction forming an average angle with the axial direction that is strictly smaller than the average angle formed by the overall direction of at least one axially inner part of the transverse cut of the above or each sound dispersion pair or trio.

[0087] Specifically, in the part of the tread surface corresponding to the axial part, the ground contact surface is straight. Conversely, in the part of the tread surface corresponding to the axially outer part, the ground contact surface is rounded due to the curvature of the tire. As a result, the leading edge of the axially inner part gradually contacts the ground, that is, over a relatively long period, due to the relatively large angle and straightness of the ground contact surface in the axially inner part, thereby forming a substantially zero average angle with the axial direction, and the noise is limited compared to a cut where the entire leading edge contacts the ground simultaneously. Similarly, due to the small angle and roundness of the ground contact surface in the axially outer part, the leading edge also gradually comes into contact with the ground, which also contributes to the limitation of noise.

[0088] That is, advantageously, in order to reduce as much as possible the noise generated by the outer portions in the axial direction, the average angle formed by the overall direction of the outer portions in the axial direction with the axial direction is arbitrarily strictly less than 25°, preferably 20° or less, more preferably 15° or less.

[0089] It is preferable that the average angle formed by the overall direction of the outer portions in the axial direction with the axial direction is substantially the same for each of the above or each transverse cut of each sound dispersion pair or trio.

[0090] Furthermore, in an optional embodiment, the outer portion in the axial direction has a width that is strictly greater than the width of the axial portion. As a result, the wide outer portion in the axial direction enables substantially discharging water from the contact surface between the tread surface and the ground on which the tire travels.

[0091] The outer portion in the axial direction optionally has a width in the range of 0.7 mm to 5.0 mm, preferably in the range of 1.0 mm to 5.0 mm, preferably in the range of 2.0 mm to 4.5 mm.

[0092] The outer portion in the axial direction optionally has a depth in the range of 2.0 mm to 5.5 mm.

[0093] In yet another embodiment, each of the above or each transverse cut of each sound dispersion pair or trio includes an axial end portion formed outside the axial direction of at least one of the first and second axial transverse portions and communicating with the wide outer portion in the axial direction. This promotes the discharge of water from the contact surface between the tread surface and the ground on which the tire travels.

[0094] The above features relate to the transverse cuts formed in at least one of the first and second axial transverse portions. In some preferred embodiments, they can also be applied to the above or each transverse cut of each sound dispersion pair or trio formed in each of the first and second axial transverse portions.

[0095] In the conventional method, a tire includes a crown, two sidewalls, and two beads, and each sidewall connects each bead to the crown. Also in the conventional method, the crown includes a tread and a crown reinforcement disposed radially inward of the tread. The tire also includes, radially inside the crown reinforcement, a carcass reinforcement fixed to each bead and extending radially within each sidewall and axially within the crown.

[0096] In the conventional method, the crown reinforcement includes at least one crown layer including reinforcing elements. These reinforcing elements are preferably fabric or metallic filamentary elements.

[0097] In an embodiment for obtaining the performance aspects of a tire known as a radial tire, for example, as defined by ETRTO, the carcass reinforcement includes at least one carcass layer, and the above or each carcass layer includes filamentary carcass reinforcing elements, and each filamentary carcass reinforcing element extends in a substantially main direction forming an angle in the range of 80° to 90° with the circumferential direction of the tire in absolute value.

[0098] The present invention will be better understood by reading the following description given merely as a non-limiting example and in relation to the drawings.

Brief Description of the Drawings

[0099]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0100] A coordinate system X, Y, Z corresponding to the normal axial direction (Y), radial direction (Z), and circumferential direction (X) of the tire is shown in the figure related to the tire.

[0101] FIGS. 1 to 3 show a tire denoted by the overall reference numeral 10 according to the present invention. The tire 10 has a substantially annular shape around a turning axis substantially parallel to the axial direction Y. The tire 10 is for a passenger car and has a size of 205 / 55R16. The tire 10 is a summer tire. In various figures, the tire 10 is shown as new, that is, not yet having run.

[0102] Referring to FIG. 2, the tire 10 includes a crown 12, and the crown 12 includes a tread 14 intended to contact the ground when the tire is running, and a crown reinforcement 16 extending in the circumferential direction X within the crown 12. The tire 10 also includes an airtight layer 18 with respect to the inflation gas, and this airtight layer is intended to define an internal cavity closed using the mounting support of the tire 10 in a state where the tire 10 is mounted on a mounting support, for example, a rim.

[0103] The crown reinforcement 16 includes an active reinforcement 20 and a hoop reinforcement 22. The active reinforcement 16 includes at least one active layer, and in this case, two active layers, that is, a radially outer active layer 26 and a radially inner active layer 24 disposed radially inward of the radially outer active layer 26.

[0104] The hoop reinforcement 22 includes at least one, in this case one hooping layer 28.

[0105] The crown reinforcement 16 supports the tread 14 radially. In this case, the hoop reinforcement 22, in this example the hooping layer 28, is arranged radially outside the working reinforcement 20 and is thus inserted radially between the working reinforcement 20 and the tread 14.

[0106] The tire 10 includes two sidewalls 30 that continue radially inwardly of the crown 12. The tire 10 also includes two beads 32 radially inwardly of the sidewalls 30. Each sidewall 30 connects each bead 32 to the crown 12.

[0107] The tire 10 includes a carcass reinforcement 34 wound around a bead wire 33, which in this example is fixed to each bead 32. The carcass reinforcement 34 extends radially within each sidewall 30 and axially within the crown 12 radially inwardly of the crown reinforcement 16. The crown reinforcement 16 is arranged radially between the tread 14 and the carcass reinforcement 34. The carcass reinforcement 34 includes at least one carcass layer 36.

[0108] Referring to FIG. 2, the tire 10 includes a tread layer 110 and a lining layer 112 for the tread layer 110. The lining layer 112 is arranged radially inside the tread layer 110 and has a very low rolling resistance.

[0109] Referring to FIGS. 2 and 3, each working layer 24, 26, the hooping layer 28, and the carcass layer 36 include an elastomeric matrix in which one or more filamentary reinforcing elements of the corresponding layer are embedded.

[0110] The hoop reinforcement 22, in this example the hooping layer 28, includes one or more filamentary hoop reinforcing elements 280, which are wound helically circumferentially in a main direction D0 forming an angle AF with the circumferential direction X of the tire 10 that is 10° or less, preferably 7° or less, more preferably 5° or less in absolute value. In this case, AF = -5°.

[0111] Each radially inner actuating layer 24 and radially outer actuating layer 26 includes filamentary actuating reinforcement elements 240, 260 extending in main directions D1, D2 forming opposite angles AT1 and AT2, respectively, and the main directions D1, D2 are strictly greater than 10° in absolute value with respect to the circumferential direction X of the tire 10, preferably in the range of 15° to 50°, more preferably in the range of 15° to 30°. In this case, AT1 = -26° and AT2 = +26°.

[0112] The carcass layer 36 includes a filamentary carcass reinforcement element extending in a main direction D3 forming an angle AC such that the absolute value with respect to the circumferential direction X of the tire 10 is greater than 60°, preferably in the range of 80° to 90°, and in this case, AC = +90°.

[0113] Each filamentary hoop reinforcement element 280, actuating reinforcement elements 240, 260, and carcass reinforcement element 360 is, for example, the same as those described in International Publication No. WO 2021 / 250331, International Publication No. WO 2022 / 074341, and International Publication No. WO 2022 / 069819.

[0114] Referring to FIGS. 1 and 2, the tread 14 includes a tread surface 38, whereby the tread 14 contacts the ground. The tread surface 38 is intended to contact the ground when the tire 10 travels on the ground. The tread surface 38 is axially delimited by first and second axial edges 41, 42 passing through respective points N disposed on both sides of the meridian plane M, and in that case, the angle between the tangent T to the tread surface 38 passing through this point and the straight line R parallel to the axial direction Y passing through this point is equal to 30°.

[0115] The tread 14 includes an axially central portion P0 and first and second axially transverse portions P1, P2 disposed axially outside the axially central portion P0 on both axial sides of the axially central portion P0 with respect to the meridian plane M of the tire 10. Each of the first and second axially transverse portions P1, P2 has an axial width L1, L2 such that L1 = 30.3 mm and L2 = 25.4 mm.

[0116] The tread 14 includes main circumferential cuts where N > 1, in this case N main circumferential grooves, including first, second, third, and fourth main circumferential cuts respectively denoted by reference numerals 52, 54, 56, and 58. The first and second main circumferential cuts 52, 54 are disposed on both axial sides of the axis of the meridian plane M of the tire 10 and are the outermost main circumferential cuts in the axial direction of the tread 14.

[0117] The first axial transverse portion P1 and the second axial transverse portion P2 are respectively disposed axially outside the first axially outer main circumferential cut 52 and the second axially outer main circumferential cut 54. The first axial transverse portion P1 extends axially from the first axial edge 41 of the tread surface 38 to the axial outer edge 43 of the first main circumferential cut 52. The second axial transverse portion P2 extends axially from the second axial edge 42 of the tread surface 38 to the axial outer edge 44 of the second main circumferential cut 54.

[0118] Each main circumferential cut 52 - 58 has a depth Hr in the range from 4.00 mm to the tread pattern height Hs, preferably in the range from 5.00 mm to the tread pattern height Hs, more preferably in the range from 5.50 mm to the tread pattern height Hs. Each depth Hr is 50% or more of the tread pattern height Hs. In this case, for the first and second axially outer main circumferential cuts 52, 54 of the axially central portion P0, Hs = 6.5 mm and Hr1 = 6.3 mm, and for each main circumferential cut 56, 58, Hr2 = 6.5 mm. That is, each main circumferential cut 52, 54, 56, 58 advantageously has a depth such that Hr1 / Hs ≧ 75%, Hr2 / Hs ≧ 75%, more preferably Hr1 / Hs ≧ 90%, Hr2 / Hs ≧ 90%.

[0119] Each main circumferential cut 52 - 58 has an axial width Lr1, Lr2, Lr3, Lr4 in the range of 1.0 mm or more, preferably 5.0 mm or more, more preferably in the range from 5.0 mm to 20.0 mm. In this case, Lr1 = 6.6 mm, Lr2 = 11.7 mm, Lr3 = 8.8 mm, and Lr4 = 10.0 mm.

[0120] The axially central portion P0 includes a central rib, and in this case, includes first, second, and third central ribs denoted by reference numerals 62, 64, and 66, respectively. Each of the central ribs 62, 64, 66 is axially disposed between two adjacent main circumferential cuts 52 to 58.

[0121] Each of the central ribs 62, 64, 66 includes transverse cuts 74, 75, 76 having a width equal to 0.4 mm and a depth equal to 3.0 mm.

[0122] Each of the first and second axially transverse portions P1, P2 includes first and second transverse ribs denoted by reference numerals 68, 70, respectively, and in this case, each includes the first and second transverse ribs 68, 70, respectively. Each of the first and second axially transverse portions P1, P2 includes axially extending portions P11, P21 having an axial width equal to 50% of the axial widths L1, L2 of the first and second axially transverse portions P1, P2, respectively. Each of the axially extending portions P11, P21 extends axially outward from the respective axially outer edges 43, 44, from which the first and second axially outer main circumferential cuts 52, 54 extend.

[0123] The tread 14 is partially formed in at least one of the first and second axially transverse portions P1, P2, and in this case, includes N transverse cuts 80, 90 that are each partially formed in the first and second axially transverse portions P1, P2, respectively. In this case, N = 87. As a result, the N transverse cuts 80, 90 form N pairs of circumferentially adjacent transverse cuts 80 in the circumferential rotation direction around the tire 10. Similarly, the tread 14 includes N, in this case N = 87, trios of circumferentially adjacent transverse cuts 80 in the circumferential rotation direction S around the tire 10. FIG. 2 shows the bottom of the cut 80 as a dashed line.

[0124] Each of the transverse cuts 80, 90 includes a narrow-width portion 82, 92 and a wide-width portion 84, 94, respectively.

[0125] Each narrow-width portion 82, 92 includes axially inner portions 86, 96 that extend within the axial portions P11, P21 of the respective first and second axially transverse portions P1, P2. Each narrow-width portion 82, 92 also includes additional portions 88, 98 that are disposed outside the axial portions P11, P21 of the respective first and second axially transverse portions P1, P2.

[0126] Each wide-width portion 84, 94 includes axially outer portions, which in this case are constituted by axially outer portions 84, 94 that are disposed outside the axial portions P11, P21 of the respective first and second axially transverse portions P1, P2. Each axially outer portion 84, 94 communicates with each axially inner portion 86, 96 respectively and is disposed axially outside each axially inner portion 86, 96.

[0127] Each axially inner portion 86, 96 is the axially innermost portion of each transverse cut 80, 90. Each axially inner portion 86, 96 reaches into each of the adjacent main circumferential cuts 52, 54 respectively.

[0128] Each axially outer portion 84, 94 is the axially outermost portion of each transverse cut 80, 90.

[0129] Each transverse cut 80, 90 extends along the axial lengths Lot1, Lot2 of this component formed in the respective first and second axially transverse portions P1, P2 among each transverse cut 80, 90. In this case, Lot1 = L1 = 30.3 mm and Lot2 = L2 = 25.4 mm. Each axially inner portion 86, 96 of each transverse cut 80, 90 extends along axial lengths Li1, Li2 that are equal to at least 20%, preferably at least 35%, and in this case 50% of the axial lengths Lot1, Lot2 of this component formed in the respective first and second axially transverse portions of each transverse cut 80, 90. In this case, Li1 = 15.2 mm and Li2 = 12.7 mm.

[0130] The inner portions 86 and 96 in each axial direction have a width La in the range of 0.2 mm to 2.2 mm, preferably 0.2 mm to 1.0 mm, more preferably 0.2 mm to 0.6 mm, and even more preferably 0.2 mm to 0.5 mm. In this case, La = 0.4 mm. The inner portions 86 and 96 in each axial direction have a depth in the range of 2.0 mm to 5.5 mm, preferably 3.0 mm to 5.0 mm, and in this example, it is equal to 4.5 mm.

[0131] The outer portions 84 and 94 in each axial direction have a width Lb that is strictly larger than the width of the inner portions 86 and 96 in each axial direction, respectively. Each width Lb is in the range of 0.7 mm to 5.0 mm, preferably 1.0 mm to 5.0 mm, more preferably 2.0 mm to 4.5 mm. In this case, depending on the pattern described later to which the notch belongs, it is equal to 2.3 mm, 2.8 mm, or 3.3 mm. The outer portions 84 and 94 in each axial direction have a depth in the range of 2.0 mm to 5.5 mm, and in this case, it is equal to 5.1 mm.

[0132] The tire 10 is obtained by molding a green tire with a mold including a plurality of different patterns. In FIG. 1, the joint J between two adjacent patterns in the circumferential direction is shown by a continuous line. In the case of the present invention, the mold includes three different patterns randomly distributed for molding the tread 14. That is, the tread 14 includes three different patterns A, B, and C distributed in the circumferential rotation direction S around the tire as follows: AABACBBCCABCBABAAABBCBAABCCCBAAAABBCBCBAAA BCCCBAAAAAABCBCCCBAAAABCCBABCCCBAAAAAABCBABAB.

[0133] Here, only the transverse notch 80 formed at least partially in the first axial transverse portion P1 will be described. The characteristics of the transverse notch 90 formed at least partially in the second axial transverse portion P2 can be inferred by making necessary modifications thereto.

[0134] The inner axial portions 86 of each transverse cut 80 of each pattern A, B, C extend in an overall direction forming a non-zero average angle with the axial direction Y. In the illustrated embodiment, the average angle of at least 25%, preferably at least 50%, more preferably at least 75%, and in this case 100% of the inner axial portions 86 of the transverse cut 80 is equal to a value taken from the list of the first, second, and third values FA, FB, FC. The values of the angles FA, FB, FC are different in pair units. The outer axial portions 84 of each transverse cut 80 extend in an overall direction forming a non-zero average angle FG with the axial direction Y. The non-zero average angle FG is substantially the same for each transverse cut 80.

[0135] More specifically, the average angle of at least 15%, preferably at least 25%, and in this case 41% of the inner axial portions 86 of the transverse cut 80 is equal to the first value FA, the average angle of at least 15%, preferably at least 25%, and in this case 32% of the inner axial portions 86 of the transverse cut 80 is equal to the second value FB, and the average angle of at least 15%, preferably at least 25%, and in this case 27% of the inner axial portions 86 of the transverse cut 80 is equal to the third value FC.

[0136] The average angles of at least 25%, preferably at least 35%, and in this case 61% of the inner axial portions 86 of N pairs of N circumferentially adjacent transverse cuts 80 are different.

[0137] The average angles of at least 15%, preferably at least 20%, and in this case 21% of the inner axial portions 86 of N trios of N circumferentially adjacent transverse cuts 80 are different in pair units.

[0138] The non-zero average angle of each inner axial portion 86, 96 is 50° or less. In this case, FA = 5°, FB = 25°, FC = 45°. The average angle FG is strictly less than 25°, preferably 20° or less, more preferably 15° or less, and in this case is equal to 10° regardless of patterns A, B, C.

[0139] For each of the N transverse cuts 80, the width La of each axially inner portion 86 is, in this case, such that 1 ≦ Lamax / La ≦ 4.0, preferably 1 ≦ Lamax / La ≦ 3.2, where Lamax is the maximum value of the width of the axially inner portion 86 of the transverse cut 80. In this case, Lamax = La = 0.4 mm.

[0140] The transverse cuts 80 formed in the first axially transverse portion P1 include a plurality of sound dispersion pairs and a plurality of sound dispersion trios, which will be described in more detail below.

[0141] In FIG. 1 showing the arrangement of the pattern AABACBBCCA, a plurality of sound dispersion pairs and trios can be determined. There are sound dispersion pairs and trios having transverse cuts 80 that are not circumferentially adjacent in the rotational direction S, and there are also sound dispersion pairs and trios having transverse cuts 80 that are circumferentially adjacent in the rotational direction S.

[0142] Referring to FIG. 1, first, with respect to the sound dispersion pair having two transverse cuts 80 exemplified by the first and second transverse cuts 801, 802 that are not circumferentially adjacent in the rotational direction S and also with respect to the sound dispersion pair having transverse cuts 811, 812 that are circumferentially adjacent in the rotational direction S and exemplified by the first and second transverse cuts 811, 812, the same description will be given.

[0143] Each of the first and second transverse cuts 801, 802 includes axially inner portions 861, 862 that extend in the overall direction forming a first non-zero average angle F1 and a second non-zero average angle F2 with the axial direction Y, respectively. The first average angle F1 is different from the second average angle F2. Similarly, each of the first and second transverse cuts 811, 812 includes axially inner portions 871, 872 that extend in the overall direction forming a first non-zero average angle F11 and a second non-zero average angle F12 with the axial direction Y, respectively. The first average angle F11 is different from the second average angle F12.

[0144] The first and second average angles F1, F2 and F11, F12 are equal to values taken from at least a list of first and second different values, in this case from a list of first, second, and third different values in pairs, the list being composed of the values FA, FB, FC.

[0145] For the illustrated pair, F1 = FA, F2 = FC, F11 = FC, F12 = FB.

[0146] The difference in absolute value between the first average angle and the second average angle of each sound dispersion pair is 40° or less and 5° or more, preferably 10° or more. In this case, |F1 - F2| = 40°, |F11 - F12| = 20°.

[0147] Regarding a sound dispersion pair including first and second transverse cuts adjacent circumferentially in the rotational direction S, the difference in absolute value between the first average angle and the second average angle of at least 25%, preferably at least 50%, in this case 57% of the sound dispersion pairs of the first and second transverse cuts adjacent circumferentially is 20° or less and 5° or more, preferably 10° or more. This 57% of the sound dispersion pairs includes the sound dispersion pairs including the first and second transverse cuts 811, 812. Specifically, |F11 - F12| = 20°.

[0148] Here, still referring to FIG. 1, an explanation of a sound dispersion trio including three transverse cuts 80 exemplified by the first, second, and third transverse cuts 801, 812, 802 that are not adjacent circumferentially in the rotational direction S is given, and an explanation of a sound dispersion trio including three transverse cuts 80 exemplified by the first, second, and third transverse cuts 801, 811, 812 that are adjacent circumferentially in the rotational direction S is also provided.

[0149] In the case of a sound dispersion trio including first, second, and third transverse cuts 801, 812, 802 that are not adjacent in the circumferential direction, the first, second, and third average angles F1, F12, F2 are different in pair units. Similarly, in the case of a sound dispersion trio including first, second, and third transverse cuts 801, 811, 812 that are adjacent in the circumferential direction, the first, second, and third average angles F1, F11, F12 are different in pair units.

[0150] The first, second, and third average angles F1, F12, F2 and F1, F11, F12 are equal to values taken from at least a list of different values for the first, second, and third, and in this case, a list of different values for the first, second, and third in pair units, and this list is composed of values FA, FB, FC.

[0151] The absolute value differences between the first and second average angles of each sound dispersion trio, between the second and third average angles of each sound dispersion trio, and between the first and third average angles of each sound dispersion trio are 40° or less and 5° or more, preferably 10° or more. Here, in the case of a sound dispersion trio including first, second, and third transverse cuts 801, 812, 802 that are not adjacent in the circumferential direction, |F1 - F12| = 20°, |F12 - F2| = 20°, |F1 - F2| = 40°. In the case of a sound dispersion trio including first, second, and third transverse cuts 801, 811, 812 that are adjacent in the circumferential direction, |F1 - F11| = 40°, |F11 - F12| = 20°, |F1 - F12| = 20°.

[0152] Regarding a sound dispersion trio including first, second, and third transverse cuts that are adjacent in the circumferential direction in the rotational direction S, at least 25%, preferably at least 50%, more preferably at least 75%, and in this case 100% of the absolute value differences between one of the first, second, and third average angles and at least one of the other first, second, and third average angles are 20° or less and 5° or more, preferably 10° or more.

[0153] The non-zero average angle FG of the axial outer portions 84, 94 of the transverse cuts 80, 90 of each sound dispersion pair or trio is strictly smaller than the average angle formed by the overall direction of the axial inner portion of at least one of the transverse cuts of each sound dispersion pair or trio, and in this case, it is smaller than the angles F2, F11, and F12.

[0154] Comparative test

[0155] The above-described tire 10 was compared with a reference tire shown in FIG. 4 and denoted by the reference symbol T. The reference tire T is identical to the tire 10 except that the transverse cuts 80, 90 are all identical to the cuts 812 of the tire 10.

[0156] By mounting the tire 10 and the reference tire T on the same vehicle running under the same conditions, the external noises generated by them were measured in turn. The vehicle was run on a track certified by UTAC in accordance with the ISO 10844 standard. The segmented measurement zones on the track were equipped with vibration-acoustic acquisition materials manufactured by Muller-BBM. The noise measured on site was corrected as a function of the ground temperature as shown in UN Regulation R117.

[0157] In the first test, the noises generated by each tire were measured at different steady speeds of 40 km / h, 50 km / h, 60 km / h, 70 km / h, 80 km / h, and 90 km / h. FIG. 5 shows the external noise B generated by the tire 10 and represented in dB shown by the curve 10 and the external noise B generated by the tire T and represented in dB shown by the curve T with respect to different steady speeds V expressed in km / h.

[0158] At 50 km / h and 80 km / h, which are the conventional speeds for evaluating the noise performance of tires for passenger cars representing the usage conditions in urban areas and around urban areas, the tire 10 generates at least 1 dB less noise than the reference tire T, and it will be observed that there is a significant improvement under these two usage conditions.

[0159] A second test was used to measure the noise generated by each tire when reaching a speed of 50 km / h at different accelerations. When this speed of 50 km / h was reached, the acceleration of the vehicle was also measured. FIG. 6 shows, for different accelerations A expressed in m / s 2 units, the external noise B expressed in dB units generated by tire 10 and shown by curve 10, and the external noise B expressed in dB units generated by tire T and shown by curve T.

[0160] Here again, regardless of the acceleration used, it will be observed that tire 10 generates at least 1 dB less noise than the reference tire T and shows a significant improvement regardless of the acceleration conditions.

[0161] The present invention is not limited to the above-described embodiments.

[0162] Specifically, it is possible to assume an embodiment in which not all of the transverse cuts formed in the first and second axial direction transverse portions or one of them belong to a sound dispersion pair or trio. That is, in a modification of the previous embodiment, in addition to the transverse cuts 80, 90, transverse cuts that are all the same and have a width La1 equal to, for example, 3.0 mm may be possible. These transverse cuts do not satisfy the relationship of 1 ≦ La1 / La2 ≦ 3.0 (in this case, La2 = 0.5 mm and La1 > 1.5 mm), and thus do not belong to a sound dispersion pair or trio.

[0163] In other embodiments, each of the first, second, and third non-zero average angles of the axially inner portions of the first, second, and third transverse cuts of each sound dispersion pair or trio is 50° or less, preferably 40° or less, and more preferably in the range of 5° to 40°. For example, FA = 8°, FB = 27°, and FC = 35° may be assumed.

[0164] In still other embodiments, it is considered possible to assume that the tread has no sound dispersion trios and has only sound dispersion pairs.

Description of Symbols

[0165] 10 Tire 38 Tread Surface 82, 92 Narrow Portion 84, 94 Wide Portion Meridian Plane of M Tire

Claims

1. The tire (10) includes a tread (14) intended to contact the ground through the tread surface (38) when the tire (10) is running, - Main circumferential cuts (52, 54, 56, 58) having a depth (Hr1, Hr2) of 50% or more of the tread pattern height (Hs), and including first and second axially outer main circumferential cuts (52, 54) arranged on both sides in the axial direction of the meridional plane (M) of the tire (10), wherein the first and second axially outer main circumferential cuts (52, 54) are the outermost main circumferential cuts in the axial direction of the tread (14), - A first axial transverse portion (P1) is positioned axially outward of the first axially outward main circumferential cut (52) and extends axially from the first axial edge (41) of the tread surface (38) to the axial outer edge (43) of the first axially outward main circumferential cut (52), - A second axial lateral portion (P2) is positioned axially outward of the second axially outward main circumferential cut (54) and extends axially from the second axial edge (42) of the tread surface (38) to the axial outer edge (44) of the second axially outward main circumferential cut (54), Includes, At least one of the first and second axial transverse portions (P1, P2) has an axial width (Li1, Li2) equal to 50% of the axial width (L1, L2) of at least one of the first and second axial transverse portions (P1, P2), and at least one of the first and second axial transverse portions (P1, P2) includes an axial portion (P11, P21) extending axially outward from the axial outer edge (43, 44) of the first or second axially outward main circumferential cut (52, 54) extending therefrom, A tire (10) for a passenger car, The tread (14) includes at least transverse cuts (80, 90) formed at least partially in at least one of the first and second axial transverse portions (P1, P2), Each transverse cut (80, 90) includes an axial inner portion (86, 96) extending within at least one of the axial portions (P11, P21) of the first and second axial transverse portions (P1, P2), The transverse cut (80, 90) formed in at least one of the first and second axial transverse portions (P1, P2) includes at least one sound dispersion pair comprising the first and second transverse cuts (801, 802, 811, 812), and each axial inner portion (861, 862, 871, 872) of each first and second transverse cut (801, 802, 811, 812) of the sound dispersion pair is, - If La1 > 1.5 mm and La2 > 1.5 mm, then 1 ≤ La1 / La2 ≤ 2.

5. - If La1 > 1.5 mm and La2 ≤ 1.5 mm, then 1 ≤ La1 / La2 ≤ 3.

0. - When La1 ≤ 1.5 mm, then 1 ≤ La1 / La2 ≤ 4.0, Having widths La1 and La2 such that, Each of the first and second transverse notches (801, 802, 811, 812) of the aforementioned or each of the sound dispersion pairs has an axial inner portion (861, 862, 871, 872) that extends in the overall direction, forming first and second non-zero mean angles (F1, F2, F11, F12) with respect to the axial direction (Y), The first average angles (F1, F11) of the axially inner portions (861, 871) of the first transverse cuts (801, 811) of the aforementioned or each sound dispersion pair are different from the second average angles (F2, F12) of the axially inner portions (862, 872) of the second transverse cuts (802, 812) of the sound dispersion pair. A tire (10) characterized by the following features.

2. The tire (10) according to claim 1, wherein the first and second non-zero mean angles (F1, F2, F11, F12) of the axially inner portions (861, 862, 871, 872) of the first and second transverse cuts (801, 802, 811, 812) of each of the first and second transverse cuts (801, 802, 811, 812) of each of the sound dispersion pairs are 50° or less.

3. The tire (10) according to claim 1, wherein the absolute difference between the first average angle (F1, F11) and the second average angle (F2, F12) of the aforementioned or each sound dispersion pair is 40° or less.

4. The tire (10) according to claim 1, wherein the absolute difference between the first average angle (F1, F11) and the second average angle (F2, F12) of the aforementioned or each sound dispersion pair is 5° or more.

5. If the average angles of the first and second (F1, F2, F11, F12) are equal to a value taken from at least the first and second different lists of values ​​(FA, FB, FC), - The average angle of the axially inward portion (86, 96) of at least 25% of the transverse cut (80, 90) of at least one of the first and second axially lateral portions (P1, P2) is equal to one of the at least first and second different values ​​(FA, FB, FC), - Each axial inner portion (86, 96) of each transverse cut (80, 90) whose average angle is equal to one of the first and second different values ​​(FA, FB, FC) is, - When Lamax > 1.5 mm and La > 1.5 mm, then 1 ≤ Lamax / La ≤ 2.

5. - When Lamax > 1.5 mm and La ≤ 1.5 mm, then 1 ≤ Lamax / La ≤ 3.0, - When Lamax ≤ 1.5 mm, then 1 ≤ Lamax / La ≤ 4.

0. Having a width La such that, where Lamax is the maximum width of the axial inner portion (86, 96) of the transverse cut (80, 90) which has an average angle equal to one of the first and second distinct values ​​(FA, FB, FC), The tire (10) according to claim 1.

6. The transverse cuts (80, 90) formed at least partially in at least one of the first and second axial transverse portions (P1, P2) include at least one tonal dispersion trio comprising first, second, and third transverse cuts (801, 802, 811, 812), The above or each first, second, and third transverse cut (801, 802, 811, 812) of each tonal dispersion trio includes an axially inward portion (861, 862, 871, 872) extending within the axial portion of at least one of the first and second axially transverse portions (P1, P2), Each of the axial inner portions (861, 862, 871, 872) of the first, second, and third transverse cuts (801, 802, 811, 812) of the aforementioned sound dispersion trio, - If La1 > 1.5 mm and La3 > 1.5 mm, then 1 ≤ La1 / La3 ≤ 2.

5. - If La1 > 1.5 mm and La3 ≤ 1.5 mm, then 1 ≤ La1 / La3 ≤ 3.

0. - When La1 ≤ 1.5 mm, then 1 ≤ La1 / La3 ≤ 4.0, It has widths La1 ≥ La2 ≥ La3 such that The axial inner portions (861, 862, 871, 872) of the first, second, and third transverse cuts (801, 802, 811, 812) of the aforementioned or each tonal dispersion trio extend in the overall direction, forming the first, second, and third non-zero mean angles (F1, F2, F11, F12) with respect to the axial direction (Y), The average angles (F1, F2, F11, F12) of the first, second, and third transverse cuts (801, 802, 811, 812) of the axial inner portions (861, 862, 871, 872) of the first, second, and third transverse cuts (801, 802, 811, 812) of the aforementioned or each tonal arpeggio trio differ on a pair basis. The tire (10) according to claim 1.

7. The tire (10) according to claim 1, wherein the first and second transverse cuts (801, 811, 812) of the first or each sound dispersion pair are adjacent in the circumferential direction, and the absolute difference between the first average angle (F1, F11, F12) and the second average angle (F1, F11, F12) of the first and second transverse cuts (801, 811, 812) of the first or each sound dispersion pair that are adjacent in the circumferential direction is 20° or less.

8. The tire (10) according to claim 1, wherein the first and second transverse cuts (801, 811, 812) of the first or each sound dispersion pair are adjacent in the circumferential direction, and the absolute difference between the first average angle (F1, F11, F12) and the second average angle (F1, F11, F12) of the first and second transverse cuts (801, 811, 812) of the first or each sound dispersion pair that are adjacent in the circumferential direction is 5° or more.

9. When the tread (14) includes N circumferentially adjacent transverse cuts (80, 90) that form N pairs of circumferentially adjacent transverse cuts (80, 90) in the circumferentially adjacent transverse direction (S) around the tire, the width La of each axially adjacent inner portion (86, 96) of the N circumferentially adjacent transverse cuts (80, 90) is - When Lamax > 1.5 mm and La > 1.5 mm, then 1 ≤ Lamax / La ≤ 2.

5. - When Lamax > 1.5 mm and La ≤ 1.5 mm, then 1 ≤ Lamax / La ≤ 3.0, - When Lamax ≤ 1.5 mm, then 1 ≤ Lamax / La ≤ 4.

0. This is the case where Lamax is the maximum width of the axially inner portion (86, 96) of the transverse cuts (80, 90) adjacent to the circumferential direction of the N pairs of transverse cuts (80, 90), The average angles of the axially inward portions of at least 25% of the N pairs of circumferentially adjacent transverse cuts (80, 90) are different. The tire (10) according to claim 1.

10. The system includes multiple sound dispersion pairs, each containing first and second transverse notches (80, 90) adjacent in the circumferential direction of rotation (S) around the tire, The absolute difference between the first average angle and the second average angle for at least 25% of the sound dispersion pairs of circumferentially adjacent first and second transverse notches (80, 90) is 5° or more and 20° or less. The tire (10) according to claim 1.

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