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CA-3262441-C - VEHICLE WHEEL TYRE

CA3262441CCA 3262441 CCA3262441 CCA 3262441CCA-3262441-C

Abstract

A tyre (1) comprises a plurality of blocks (5, 6) which are defined on a tread band (2) and at least one first sipe (10; 20) which is formed on each block. The first sipe (10; 20) extends in a first longitudinal direction (A) and comprises a first linear portion (11) which substantially extends along the first longitudinal direction (A), a single-wave portion (12) which extends in continuation of the first linear portion (11), and a second linear portion (13) which extends in continuation of the single-wave portion (12). The single-wave portion (12) comprises a first segment (14) which is inclined and which extends from the first linear portion (11) as far as a first peak (15), a second segment (16) which is inclined and which extends from the first peak (15) as far as an opposite second peak (17) and a third segment (18) which is inclined and which extends from the second peak (17) as far as the second linear portion (13). The second segment (16) of the single-wave portion (12) is inclined with respect to the first longitudinal direction (A) at an angle greater than the first segment (14) and the third segment (18).

Inventors

  • Giovanni Casarotto
  • Riccardo GUERRA
  • Diego Ettore Speziari

Assignees

  • PIRELLI TYRE S.P.A.

Dates

Publication Date
20260505
Application Date
20230627
Priority Date
20220727

Claims (20)

  1. 27 Claims: 1. A tyre (1) comprising a tread band (2), a tread surface (3) which is radially external with respect to said tread band, a 5 plurality of blocks (5, 6) which are defined on said tread band (2) and at least one first sipe (10; 20) which is formed on each block of said plurality of blocks (5, 6), said first sipe (10; 20) being open at said tread surface (3) so as to define a first longitudinal development direction (A) of said first sipe (10), 10 wherein said first sipe comprises: - a first linear portion (11) which substantially extends along said first longitudinal direction (A), - a single-wave portion (12) which extends in continuation of said first linear portion (11), and 15 - a second linear portion (13) which extends in continuation of said single-wave portion (12), wherein said first linear portion (11) and said second linear portion (13) are rectilinear or curvilinear with a minimum radius of curvature not less than 20 mm, 20 wherein said single-wave portion (12) comprises: - a first segment (14) which is inclined with respect to said first longitudinal direction (A) and which extends from said first linear portion (11) as far as a first peak (15), - a second segment (16) which is inclined with respect to said 25 first longitudinal direction (A) and which extends from said first peak (15) as far as a second peak (17) which is defined at the opposite side to said first peak (15) with respect to said first longitudinal direction (A) and - a third segment (18) which is inclined with respect to said first 30 longitudinal direction (A) and which extends from said second peak (17) as far as said second linear portion (13), wherein said second segment (16) is inclined with respect to said first longitudinal direction (A) at an angle greater than said first segment (14) and said third segment (18), 28 and wherein said second linear portion (13) has a length greater by at least 50% with respect to said first linear portion (11).
  2. 2. The tyre (1) according to claim 1, wherein said first segment 5 (14) and said third segment (18) of said single-wave portion (12) are inclined with respect to said first longitudinal direction (A) at an angle between 20° and 45° and wherein said second segment (16) of said single-wave portion (12) is inclined with respect to said first longitudinal direction (A) at an angle between 60° and 10 90°.
  3. 3. The tyre (1) according to any one of claims 1 and 2, wherein said second segment (16) of said single-wave portion (12) is inclined in a discordant manner with respect to said first segment 15 (14) and said third segment (18) of said single-wave portion (12).
  4. 4. The tyre (1) according to any one of claims 1 to 3, wherein said first segment (14) and said third segment (18) of said singlewave portion (12) are substantially parallel.
  5. 5. The tyre (1) according to any one of claims 1 to 4, wherein said first segment (14) of said single-wave portion (12) has a length substantially identical to said third segment (18) of said single-wave portion (12).
  6. 6. The tyre (1) according to any one of claims 1 to 5, wherein the distance of said first peak (15) from said first longitudinal direction (A) is substantially identical to the distance of said second peak (17) from said first longitudinal direction (A).
  7. 7. The tyre (1) according to any one of claims 1 to 6, wherein said second linear portion (13) has a length greater by at least 100% with respect to said first linear portion (11). 29
  8. 8. The tyre (1) according to claim 7, wherein said second linear portion (13) has a length greater by at least 200% with respect to said first linear portion (11). 5
  9. 9. The tyre (1) according to any one of claims 1 to 8, wherein said first longitudinal development direction (A) of the first sipe (10) intersects with a first edge (8) and a second edge (9) of said block, said first linear portion (11) extending towards said first edge (8) and said second linear portion (13) extending 10 towards said second edge (9), and wherein the distance of said single-wave portion (12) from said first edge (8) measured along said first longitudinal direction (A) is between 5% and 40% of the distance between said first edge (8) and said second edge (9) measured along said first longitudinal direction (A).
  10. 10. The tyre (1) according to claim 9, wherein the distance of said single-wave portion (12) from said second edge (9) measured along said first longitudinal direction (A) is at least double the distance of said single-wave portion (12) from said first edge (8) 20 measured along said first longitudinal direction (A).
  11. 11. The tyre (1) according to any one of claims 9 and 10, wherein said first linear portion (11) is open at said first edge (8) of said block (5).
  12. 12. The tyre (1) according to any one of claims 1 to 11, wherein said first linear portion (11) has a length between 2 and 5 mm.
  13. 13. The tyre (1) according to any one of claims 1 to 12, wherein 30 said first sipe (10) in the region of said first linear portion (11) has a depth less than the depth of said first sipe (10) in the region of said single-wave portion (12).
  14. 14. The tyre (1) according to any one of claims 9 to 11, wherein said second linear portion (13) is open at said second edge (9) of said block (5).
  15. 15. The tyre (1) according to any one of claims 9 to 14, wherein 5 said second linear portion (13) has a length between 4 and 25 mm.
  16. 16. The tyre (1) according to any one of claims 1 to 15, wherein said second linear portion (13) is substantially aligned with said first linear portion (11) along said first longitudinal direction 10 (A).
  17. 17. The tyre (1) according to any one of claims 1 to 16, wherein said first sipe (10) comprises only one of said single-wave portion (12).
  18. 18. The tyre (1) according to any one of claims 1 to 17, wherein there is further formed on said block (5) a second sipe (10a) which extends in a second longitudinal direction (B), said second sipe being consecutive to said first sipe (10) and having: 20 - a first linear portion (11) which substantially extends along said second longitudinal direction (B), - a single-wave portion (12) which extends in continuation of said first linear portion (11), and - a second linear portion (13) which extends in continuation of 25 said single-wave portion (12), wherein said first linear portion (11) and said second linear portion (13) are rectilinear or curvilinear with a minimum radius of curvature not less than 20 mm. 30
  19. 19. The tyre (1) according to claim 18, wherein said first sipe and said second sipe each have only one of said single-wave portion (12).
  20. 20. The tyre (1) according to claim 19, wherein said first 31 longitudinal direction (A) of said first sipe (10) and said second longitudinal direction (B) of said second sipe (10a) intersect with the first edge (8) and the second edge (9) of said block (5), and wherein: 5 - the first linear portion (11) of said first sipe (10) is open at said first edge (8) of said block, - the single-wave portion (12) of said first sipe (10) has a distance from said first edge (8), measured along said first longitudinal direction (A) of said first sipe, between 5% and 40% 10 of the distance between said first edge (8) and said second edge (9) measured along said first longitudinal direction of said first sipe (10), - the first linear portion (11) of said second sipe (10a) is open at said second edge (9) of said block (5), and 15 - the single-wave portion (12) of said second sipe (10a) has a distance from said second edge (9) measured along said second longitudinal direction (B) of said second sipe (10a) between 5% and 40% of the distance between said second edge (9) and said first edge (8) measured along said second longitudinal direction (B) of 20 said second sipe (10a).

Description

1 VEHICLE WHEEL TYRE DESCRIPTION The present invention relates to a tyre for vehicle wheels, in particular a winter tyre. A tyre generally comprises a carcass structure which is toroidally shaped about a rotation axis, and which comprises at least one carcass ply which has end edges which are engaged in respective annular anchoring structures, called bead cores. In a radially external position with respect to the carcass structure, there is provided a belt structure comprising, in the case of tyres for cars, at least two radially overlapping strips of rubberized fabric which is provided with reinforcement cords, which are usually made of metal, and which are arranged in each strip parallel with each other but crosswise with respect to the cords of the adjacent strip, preferably symmetrically with respect to the equatorial plane of the tyre. Preferably, the belt structure also further comprises, in a radially outer position at least on the ends of the underlying belt strips, a third layer of textile or metal cords, arranged circumferentially (at 0 degrees). In tyres of the tubeless-type, there is further present a radially inner layer known as a "liner" and which has characteristics of impermeability in order to obtain the air-tightness in the tyre itself. In a radially external position with respect to the belt structure, there is applied a tread band which is made of elastomer material and on which a tread surface which is intended for contact with the road surface is defined. In order also to obtain adequate road grip on a wet road surface, the tyres have a tread band which is provided with grooves with5 2 various shapes and geometries and the main object of which is to allow the evacuate the water present between the surface of the tyre and the road surface during the mutual contact. The grooves generally define on the tread band a plurality of blocks, each of which comprises a radially outer surface intended to contact with the road surface, and which therefore forms a portion of the tread surface of the tyre. Each block is further bounded at least partially by one or more walls which are defined by the grooves which surround it. In some cases, a wall of a block, or a portion thereof, is connected to the tread surface of the block by means of a chamfer, which is typically formed by a plane, suitably slanted with respect to the wall and the tread surface, and which defines an edge of the block. In the case of winter tyres, there are generally formed on the blocks of the tread band small recesses, called "sipes", which extend from the tread surface of the tyre towards the inside of the block. The function of the sipes is to provide additional gripping elements in the case of travel on snowy surfaces and to retain a certain quantity of snow, thereby improving the grip with respect to the road surface. The sipes can have very varied and different configurations from each other, for example, they can have a rectilinear or curvilinear or undulating progression. The term "circumferential" direction means a direction which is generally directed in the rotation direction of the tyre or, in any case, slightly slanted (at most by about 5°) with respect to the rotation direction of the tyre. The term "axial" direction means a direction which is substantially parallel with the rotation axis of the tyre or, at most, slightly slanted (at most by about 5°) with respect to this rotation axis5 3 of the tyre. The axial direction is generally perpendicular to the circumferential direction. The term "radial" direction means a direction perpendicularly intersecting the rotation axis of the tyre or at most which is slightly slanted (for example, at most by about 5°) with respect to the direction perpendicular to the rotation axis of the tyre. The term "equatorial plane" of the tyre means an axial centre-line plane which is perpendicular to the rotation axis of the tyre. The term "groove" means a recess portion, and which extends in a which has a width greater than or groove has a depth of at least 3 which is formed in a tread band main longitudinal direction and equal to 1.5 mm. Preferably, the mm. The term "sipe" means a recess which is formed in a tread band portion, and which extends in a main longitudinal direction, and which has a width less than 1.5 mm. The "longitudinal development direction" of the sipe is defined by the linear progression of the sipe in the region of the radially external surface of the block. The term "block" means a tread band portion which is intended for contact with the road surface, and which is delimited over the entire periphery thereof by one or more grooves and where applicable by an axial end of the tread band. Therefore, a block is considered to be both a tread band portion with a closed contour which is delimited by three or more grooves and a circumferential rib which is delimited by a pair of grooves which develop circumferentially around the tread band.5 A "central block" is defined a