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CN-122029058-A - Tire for heavy civil engineering vehicle with improved wear and durability properties

CN122029058ACN 122029058 ACN122029058 ACN 122029058ACN-122029058-A

Abstract

The present invention relates to a tyre (1) for a heavy civil engineering vehicle, said tyre (1) being able to improve the performance tradeoff between its wear life and its thermal endurance in the case of a tread having a modified tread pattern. According to the invention, the lateral portions (21) of the tread comprise an alternation of at least one first transverse incision (321) and at least one second transverse incision (322), both said first transverse incision (321) and second transverse incision (322) changing during wear, the outer groove (321E) of any first transverse incision (321) extending radially inwards through an inner cavity (321I) having an open surface, the maximum dimension (W1I) of the closed profile of which is at least equal to 10% of the width (L21) of the lateral portion (21), and extending radially inwards up to the maximum depth (D0) of the incision.

Inventors

  • O. Spencer

Assignees

  • 米其林集团总公司

Dates

Publication Date
20260512
Application Date
20241010
Priority Date
20231019

Claims (9)

  1. 1. Tyre (1) for a heavy construction site vehicle, said tyre (1) comprising a tread (2), said tread (2) comprising an arrangement of incisions (3), said incisions (3) separating raised elements (4), -The slits (3) are longitudinal slits (31) or transverse slits (32), the average line of the longitudinal slits (31) forming an angle with the circumferential direction (XX ') of at most equal to 45 °, the average line of the transverse slits (32) forming an angle with the circumferential direction (XX') of more than 45 °, When the tire is completely new, the tread (2) has a width (L0) measured along an axial direction (YY ') parallel to the axis of rotation of the tire and has a maximum depth of cut (D0) measured along a radial direction (ZZ') perpendicular to the tread surface (20), -Said tread (2) comprising, on both sides of the equatorial plane (XZ), external longitudinal incisions (311), the axial distance (LE) of the average line of said external longitudinal incisions (311) from the equatorial plane (XZ) being at least equal to 25% of the width (L0) and defining axially outwards a lateral tread portion (21), -Said lateral tread portion (21) comprises an alternation of at least one first transversal incision (321) and at least one second transversal incision (322), Each first transverse incision (321) comprising an outer groove (321E) leading to the tread surface (20), the width (W1E) of said outer groove (321E) being at least equal to 30% of its height (H1E), Each second transverse incision (322) comprising an outer sipe (322E) opening onto the tread surface, said outer sipe (322E) having a width (W2E) at most equal to 20% of its height (H2E) and continuing radially inwards by an inner groove (322I), the width (W2I) of said inner groove (322I) being at least equal to 30% of its height (H2I), Characterized in that the outer groove (321E) of each first transverse incision (321) continues radially inwards by an inner cavity (321I) with an open surface, the maximum dimension (W1I) of the closed contour of which is at least equal to 10% of the width (LL) of the side portion (21), and extends radially inwards up to a maximum incision depth (D0).
  2. 2. Tyre (1) according to claim 1, wherein the maximum dimension (W1I) of the closed profile of the open surface of the inner cavity (321I) continuing the outer groove (321E) of each first transversal incision (321) is at most equal to 30% of the width (L21) of the side portion (21).
  3. 3. Tyre (1) according to any one of claims 1 and 2, wherein the inner cavity (321I) of the outer groove (321E) continuing each first transverse incision (321) extends radially inwards up to at least 60% of the maximum incision depth (D0), preferably up to at least 70% of the maximum incision depth (D0).
  4. 4. A tyre (1) according to any one of claims 1 to 3, wherein the width (W1E) of the outer groove (321E) of each first transversal cut (321) is at least equal to 40% of its height (H1E), preferably at least equal to 50% of its height (H1E).
  5. 5. Tyre (1) according to any one of claims 1 to 4, wherein the outer groove (321E) of each first transverse incision (321) extends radially inwards up to at most 50% of the maximum incision depth (D0).
  6. 6. Tyre (1) according to any one of claims 1 to 5, wherein the width (W2E) of the external sipe (322E) of each second transverse incision (322) is at most equal to 10% of its height (H2E).
  7. 7. Tyre (1) according to any one of claims 1 to 6, wherein the external sipe (322E) of each second transverse incision (322) extends radially inwards up to at most 50% of the maximum incision depth (D0).
  8. 8. Tyre (1) according to any one of claims 1 to 7, wherein the width (W2I) of the inner groove (322I) of each second transverse incision (322) is at least equal to 40% of its height (H2I), preferably at least equal to 50% of its height (H2I).
  9. 9. Tyre (1) according to any one of claims 1 and 8, wherein the inner groove (322I) of each second transverse incision (322) extends radially inwards up to 70% of the maximum incision depth (D0), preferably up to 100% of the maximum incision depth (D0).

Description

Tire for heavy civil engineering vehicle with improved wear and durability properties Technical Field The present invention relates to a tire for a heavy construction site vehicle intended to carry heavy loads and to travel on uneven and stony ground (such as the ground of a mine). The invention relates more particularly to a tread for such a tire, wherein the performance tradeoff in terms of wear and durability at the tread edges is improved. Background The invention relates more particularly to a tyre intended to be mounted to a heavy construction site vehicle, such as a dump truck intended for transporting material collected from a quarry or surface mine. Dump trucks can experience particularly severe driving conditions of high load, sustained speed, inclined and winding routes, uneven and stony ground. As an example, at the site of mining material (e.g., ore or coal), the use of dump truck type vehicles involves an alternation of full-load outbound cycles and empty-load return cycles in a simplified form. In a full-load off-station cycle, a full-load vehicle transports mined material from a loading area at the bottom of a mine or pit primarily uphill to an unloading area, requiring tires with good traction grip. In the empty return cycle, the empty vehicle returns mainly downhill into the loading area at the bottom of the mine, requiring good tire braking grip. The road, which is often inclined, also often includes curves, requiring good lateral grip of the tire. Furthermore, the roads on which the vehicles travel are composed of materials (e.g. crushed stone and tight rock) usually from mines, in order to ensure the integrity of the road wear layers as the vehicles pass, the rocks are regularly made moist, which means that they are usually covered with sludge and water. Thus, on the one hand, there is a need for a tread that is able to effectively remove this mixture of sludge and water, ensuring a satisfactory grip on muddy ground, and on the other hand, that is able to have good wear resistance and resistance to attacks by stones present on the ground. The special use of the dump truck as described above requires special management of the tires mounted thereon. When new, tires are typically mounted on the front axle or steering axle of the vehicle. In this front position, the load applied to the tyre is generally estimated to be between 60% and 100% of its nominal load-bearing capacity, depending on whether the vehicle is running in an empty or in a full state, as defined for example by standard ISO 4250 and the standard of "tyre and rim organization" or TRA. In this load range, the tire is in contact with the ground over the entire width of the tire tread, and the tire is subjected to limited or low longitudinal forces, but to high lateral forces due to the steering of the tire. When the tire wears up to about one third (i.e., when the tread thickness is reduced by one third as compared to the original thickness when new), the tire is removed from the front axle and mounted to the rear axle or drive axle to wear the remaining two-thirds of the tread. In this rear position, the load applied to the tyre is generally estimated to be between 30% and 100% of its nominal load-bearing capacity, depending on whether the vehicle is running in an empty or in a full state. In this lower load range (corresponding to running in an unloaded state), the tire is in contact with the ground over only a portion of the tread width. In this rear position, the tire is subjected to high longitudinal (driving and braking) forces (including when only the central or intermediate portion of the tread surface is in contact with the ground in an unloaded condition) and low lateral forces. Finally, according to current practice, the tire is permanently removed from the drive shaft when the tire tread reaches a residual thickness corresponding to a fully worn condition. Tire treads (intended to constitute the peripheral portion of the tire) generally comprise at least one rubber-based material and are intended to wear upon contact with the ground through the tread surface. Typically: Radial direction representing a direction perpendicular to the rotation axis of the tyre, An axial direction or transverse direction representing a direction parallel to the rotation axis of the tyre, A circumferential direction or longitudinal direction, representing a direction tangential to the outer circumference of the tyre and perpendicular to the radial direction and to the axial direction respectively, The equatorial plane or median circumferential plane, means the plane containing the radial and circumferential directions, perpendicular to the rotation axis of the tyre and dividing the latter into two equal parts. For any state of wear of the tire, the tread geometry is characterized by an axial width measured along the axial direction (width for short) and a radial thickness measured along the radial direction (thickness for short). Convent