TIRE WITH IMPROVED TRACTION

Abstract

The present invention concerns a tire (10) comprising a tread (11) provided with a base surface (14) and with a plurality of ribs (12), each rib (12) being provided with a front wall and a rear wall, wherein, on the front wall of the rib (12), under a top portion (13) of the front wall, a shaped profile (15) is present, with a base in the portion of the tread (11) comprised between the front wall of the rib (12) and the adjacent rib, height equal to a portion of the overall height of the front wall of the rib (12) and a length that extends in the transverse direction with respect to the height of the rib (12), characterised in that said shaped profile (15) has a section that defines at least one flat surface (17) of the shaped profile (15) which is parallel, or inclined at an angle up to 20, with respect to the surface of the head (16) of the rib and which is joint to said top portion (13) of the front wall of the rib (12) by means of a connecting surface (18), at least one sharp angle (19) of the shaped profile (15) and at least one front wall (23) of the shaped profile (15), which is joint to said base surface (14) of the tread (11) by means of a connecting surface (21).

Claims

1-9. (canceled)

10. Agricultural or forestry tire (10) comprising a tread (11) provided with a base surface (14) and with a plurality of ribs (12), each rib (12) being provided with a head (16), a front wall (13) and a rear wall (25), wherein, on the front wall (13) of the rib (12), under a top portion (13) of the front wall (13), a shaped profile (15) is present, with a bottom of the shaped profile (15) in the portion of the tread (11) comprised between the front wall (13) of the rib (12) and the adjacent rib, height equal to a portion of the overall height of the front wall (13) of the rib (12) and a length that extends in the transverse direction with respect to the height of the rib (12), and wherein said shaped profile (15) is not present on the rear wall (25) of the rib (12), wherein said shaped profile (15) has a section that defines at least one flat surface (17) of the shaped profile (15), wherein said flat surface is joined to said top portion (13) of the front wall (13) of the rib (12) by means of a connecting surface (18), and wherein the shaped profile (15) comprises at least one sharp corner (19) and a front wall (23) which is joined to said base surface (14) of the tread (11) by means of another connecting surface (21), characterized in that said flat surface is parallel, or inclined at an angle up to 20, with respect to the surface of the head (16) of the rib (12) and the width of said flat surface (17) of the shaped profile (15) in the middle portion of the rib (12) and the shaped profile (15) is obtained by addition of material to the front wall (23) of the rib (12).

11. The agricultural or forestry tire (10) according to claim 10, characterised in that said top portion (13) of the front wall (13) of the rib (12) is inclined at an angle comprised between 10 and 30 with respect to the radial direction.

12. The agricultural or forestry tire (10) according to claim 10, characterised in that said flat surface (17) of said shaped profile (15) is located at a height comprised between 1 mm and 9/10 of the overall height of the rib (12).

13. The agricultural or forestry tire (10) according to claim 12, characterised in that said flat surface (17) of said shaped profile (15) is located at a height comprised between and of the overall height of the rib (12).

14. The agricultural or forestry tire (10) according to claim 10, characterised in that the width (22) of said shaped profile (15), from the sharp corner (19) to an intersection where the connecting surface and the top portion of the front wall meet, is comprised between 1 mm and 9/10 of the distance between the front wall (13) of the rib (12) and the rear wall (25) of the adjacent rib (12), at the height of said shaped profile (15).

15. The agricultural or forestry tire (10) according to claim 10, characterised in that the width (22) of said shaped profile (15), from the sharp corner (19) to an intersection where the connecting surface and the top portion of the front wall meet, is comprised between and of the width of the head (16) of the rib (12).

16. The agricultural or forestry tire (10) according to claim 10, characterised in that said shaped profile (15) has a section with steps, i.e. defines a plurality of flat surfaces of the shaped profile (15), a corresponding plurality of sharp angles and front walls of the shaped profile, wherein said steps have a height and width equal to or different from each other.

17. The agricultural or forestry tire (10) according to claim 10, characterised in that the surface of said shaped profile (15) has a different color from the rest of the tire.

Description

[0025] The present invention will now be described, for illustrative but not limitative purposes, according to its preferred embodiment, with particular reference to the figures of the accompanying drawings, wherein:

[0026] FIG. 1 shows a perspective view of a portion of a tire according to the prior art,

[0027] FIG. 2 shows a perspective view of a portion of a tire according to the present invention,

[0028] FIG. 3 shows a sectional view of a rib of the tire of FIG. 2 superimposed for comparison to a sectional view of a rib of a tire according to the prior art,

[0029] FIG. 4 shows a plan view of a portion of the tire of FIG. 2, and

[0030] FIGS. 4A, 4B, 4C each show a section view of a rib of the tire of FIG. 4, respectively in correspondence of the section line A, B and C of FIG. 4.

[0031] Referring to the figures, a tire 10 comprises a tread 11 on which a plurality of ribs 12 are made. Each rib 12 is provided with a front wall 13 and a rear wall 25, filleted at the respective ends of the so-called head 16 of the rib, the front wall 13 being the one which, during the rolling of the tire, comes first in contact with the ground.

[0032] According to the present invention, the conventional profile of a rib 12 of a tire 10 is modified by adding a shaped profile 15 to the front wall 13 of the rib 12 itself. The section of said shaped profile 15 can be rectangular, trapezoidal, or other shape, with a flat surface 17 substantially parallel, or inclined at an angle up to 20, with respect to the surface of the head 16 of the rib 12, joint to a top portion 13 of the front wall of the rib 12 by means of a curve connecting surface 18; a sharp angle 19 of the shaped profile 15, to carve the ground in a more progressive way and a front wall 23 of the shaped profile 15, coupled with the base surface 14 of the tread 11 by means of a curve connecting surface 21.

[0033] In many cases, the shaped profile 15, or at least its surface, will be made with a material of different color than the rest of the tire or at least compared to the rest of the rib 12.

[0034] The overall height 24 of the shaped profile 15 can be chosen in a range comprised between 1 mm and 9/10 of the height of the rib or lug 12, in consideration of the fact that shaped profiles 15 lower than 1 mm would be irrelevant and that shaped profiles higher than 9/10 of the height of the rib 12 would lead to a simple enlargement of the same. Preferably, in order to obtain better results in terms of traction of the tire, the height of the shaped profile 15 can be chosen between and of the overall height of the rib 12.

[0035] The width 22 of the shaped profile 15 can vary in a range comprised between 1 mm and 9/10 of the distance between the front wall 13 of the rib 12 and the rear wall 25 of the adjacent rib 12, in view of the fact that the shaped profiles 15 thinner than 1 mm would be irrelevant and that shaped profiles larger than 9/10 of the space between two ribs or lugs would close the space dedicated to the discharge of ground. Preferably, in order to obtain the better results in terms of traction of the tire, the width of the shaped profile 15 can be chosen between and of the width of the head 16 of the rib 12.

[0036] With reference in particular to FIGS. 4, 4A, 4B, 4C, the width 22 of the shaped profile 15, and more particularly of the flat surface 17 of the shaped profile 15 is greater in correspondence of the central portion of the rib 12.

[0037] In the case wherein said shaped profile 15 has a section with steps, said steps can have height and width equal to or different from each other, always within the overall limits previously said.

[0038] When the tire is in road configuration, the presence of the shaped profile 15 has the effect of increasing the bending stiffness of the rib 12, reducing the vibration of the rib 12 itself and the effect of brushing on the contact surface, which induces a greater resistance to wear and an increased driving comfort. When the tire occurs to work in field configuration, the pliability of the ground causes the tire to penetrate deep into the soil, allowing the shaped profile 15 of the rib 12 to come in contact with the ground, with the following benefits: [0039] a significant increase of the flat surface of the rib 12, which allows to increase the surface of contact along the direction of the width of the rib 12 itself, assuring greater buoyancy on soft ground, reducing the compaction of the latter; [0040] a possible increase of the front surface of the rib 12, which allows to increase the surface of contact along the direction of the depth of the rib 12; [0041] a significant increase of the edge effect, ie the concentration of efforts on said edge, which on very slippery soils allows the tire 10 better cling to the ground, producing benefits from the point of view of tensile strength and limiting slippage. This is particularly beneficial on tuft in terms of dew; and [0042] a better self-cleaning from soil and mud in the agriculture tread, due to the discontinuity in the front surface of the rib.

[0043] The present invention has been described for illustrative but not limitative purposes, according to its preferred embodiment, but it is to be understood that variations and/or modifications can be made by those skilled in the art without departing from the scope of the claims, as defined by the annexed claims.