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CN-116368020-B - Tire with improved grip for heavy civil engineering vehicles

CN116368020BCN 116368020 BCN116368020 BCN 116368020BCN-116368020-B

Abstract

The invention relates to a tyre (1) for heavy civil engineering vehicles, with the aim of improving the performance trade-off between wear life, resistance to attacks and grip. The tread (2) has an axial width L0 and comprises on each side of the equatorial plane (XZ) at least one external longitudinal incision (41) at an axial distance LE equal to at least 0.5 x L0/2 and at least one internal longitudinal incision (42) at an axial distance LI equal to at most 0.4 x L0/2, the at least one external longitudinal incision (41) comprising an external radial portion (411) open to the tread surface (3) and having an average width WE1 equal to at least 0.6 times the height HE1 of said external radial portion (411), and the at least one internal longitudinal incision (42) comprising an internal radial portion (422) not open to the tread surface (3) and having an average width WI2 equal to at least 0.6 times the height HI2 of said internal radial portion (422).

Inventors

  • W. Lichens
  • F Ba Er Bahrain

Assignees

  • 米其林集团总公司

Dates

Publication Date
20260505
Application Date
20210922
Priority Date
20200923

Claims (20)

  1. 1. Tyre (1) for heavy vehicles of the construction field type, comprising, in a new state before running, a tread (2) intended to be in contact with the ground via a tread surface (3): When a tire mounted on a nominal rim is inflated to a nominal pressure Pn and compressed under a nominal load Zn, the tread surface (3) has an axial width L0, The tread (2) comprises incisions (4) separating the raised elements (6) and having a maximum depth D0, The tread (2) comprising, on each side of the equatorial plane (XZ), at least one external longitudinal incision (41) and at least one internal longitudinal incision (42), said external longitudinal incision (41) having a bisector (ME) located at an axial distance LE at least equal to 0.5 x L0/2 with respect to the equatorial plane (XZ) of the tire, said internal longitudinal incision (42) having a bisector (MI) located at an axial distance LI at most equal to 0.4 x L0/2 with respect to the equatorial plane (XZ) of the tire, Characterized in that at least one outer longitudinal incision (41) comprises an outer radial portion opening onto the tread surface (3) and having a height HE1 and an average width WE1, said average width WE1 being at least equal to 0.6 times the height HE1, and at least one inner longitudinal incision (42) comprises an inner radial portion not opening onto the tread surface (3), said inner radial portion extending at least partly radially inside the outer radial portion of the outer longitudinal incision (41) and having a height HI2 and an average width WI2, said average width WI2 being at least equal to 0.6 times the height HI 2.
  2. 2. Tyre (1) according to claim 1, wherein the average width WE1 of the outer radial portion of the at least one outer longitudinal slit (41) is at most equal to 2 times the height HE 1.
  3. 3. Tyre (1) according to any one of claims 1 and 2, wherein an outer radial portion of the at least one outer longitudinal slit (41) extends radially inwards and downwards to a radial depth DE1 at least equal to D0/4.
  4. 4. Tyre (1) according to claim 1, wherein the outer radial portion of the at least one outer longitudinal slit (41) extends radially inwards down to a radial depth DE1 at most equal to 2 x d 0/3.
  5. 5. Tyre (1) according to claim 1, wherein at least one external longitudinal incision (41) comprises an internal radial portion leading to an external radial portion thereof, said internal radial portion having a height HE2 and an average width WE2, said average width WE2 being at most equal to 0.2 times the height HE 2.
  6. 6. Tyre (1) according to claim 1, wherein the average width WI2 of the inner radial portion of the at least one inner longitudinal slit (42) is at most equal to 2 times the height HI 2.
  7. 7. Tyre (1) according to claim 1, wherein an inner radial portion of the at least one inner longitudinal slit (42) extends radially inwards down to a radial depth DI2 at least equal to D0/2.
  8. 8. Tyre (1) according to claim 1, wherein an inner radial portion of the at least one inner longitudinal slit (42) extends radially inwards down to a radial depth DI2 at most equal to D0.
  9. 9. Tyre (1) according to claim 1, wherein at least one internal longitudinal incision (42) comprises an external radial portion leading to the tread surface (3) and to an internal radial portion thereof, said external radial portion having a height HI1 and an average width WI1, said average width WI1 being at most equal to 0.2 times the height HI 1.
  10. 10. Tyre (1) according to claim 1, when inflated to a nominal pressure Pn and compressed under a nominal load Zn, the tyre having an outer diameter D measured in the equatorial plane (YZ) and a load contact surface area of circumferential length C0, wherein at least one external longitudinal incision (41) is connected to at least NE external transverse incisions (51), said external transverse incisions (51) opening out at the axial end (21) of the tread (2), NE being at least equal to n x D/C0, such that the load contact surface area comprises at least one external transverse incision (51).
  11. 11. Tyre (1) according to claim 10, wherein the outer radial portion of the at least one outer longitudinal slit (41) extends radially inwards down to a radial depth DE1, wherein each outer transverse slit (51) comprises an outer radial portion having a height HTE1 at least equal to HE1, an average width WTE1 at least equal to 0.6 x HTE1 and a depth DTE1 at least equal to DE 1.
  12. 12. Tyre (1) according to claim 1, when inflated to a nominal pressure Pn and compressed under a load approximately equal to 0.25 x zn, mounted on a nominal rim, having an outer diameter D measured in the equatorial plane (YZ) and an empty contact surface area of circumferential length C1, wherein at least one internal longitudinal incision (42) is connected to at least NI internal transverse incisions (52), said internal transverse incisions (52) opening to the outside at the axial end (21) of the tread (2), NI being at least equal to n x D/C1, such that the empty contact surface area comprises at least one internal transverse incision (52).
  13. 13. Tyre (1) according to claim 12, wherein the inner radial portion of at least one inner longitudinal slit (42) extends radially inwards down to a radial depth DI2, wherein each inner transverse slit (52) comprises an inner radial portion having a height HTI2 at least equal to HI2, an average width WTI2 at least equal to 0.6 x HTI2 and a depth DTI2 at least equal to DI 2.
  14. 14. Tyre (1) according to claim 1, wherein at least one external longitudinal incision (41) has a bisector (ME) located at an axial distance LE at most equal to 0.8 x l0/2 with respect to the equatorial plane (XZ) of the tyre.
  15. 15. Tyre (1) according to claim 1, wherein at least one internal longitudinal incision (42) has a bisector (MI) located at an axial distance LI at least equal to 0.15 x l0/2 with respect to the equatorial plane (XZ) of the tyre.
  16. 16. Tyre (1) according to claim 15, wherein the difference between the axial distance LE and the axial distance LI is at least equal to 0.2 x l0/2.
  17. 17. Tyre (1) according to claim 1, the tread (2) having a volumetric void ratio TEV equal to the ratio between the total volume VD of incisions, measured on an unused tyre, i.e. on an uninstalled and uninstalled tyre, and the sum of the total volume VD of incisions and the total volume VR of raised elements delimited by these incisions, wherein, at any wear level between a brand-new condition corresponding to a maximum depth of incisions D0 and a worn condition corresponding to a maximum depth of incisions DR, the volumetric void ratio TEV being at least equal to 12%, wherein the maximum depth of incisions DR is at least equal to D0/10 and at most equal to D0/3.
  18. 18. Tyre (1) according to claim 1, the volumetric void ratio TEV of the tread (2) being equal to the ratio between the total volume VD of the incisions, measured on an unused tyre, i.e. on an uninstalled and uninstalled tyre, and the sum of the total volume VD of the incisions and the total volume VR of the raised elements delimited by these incisions, wherein, at any wear level between a brand-new condition corresponding to a maximum depth of incisions D0 and a worn condition corresponding to a maximum depth of incisions DR, the volumetric void ratio TEV is at most equal to 20%, wherein the maximum depth of incisions DR is at least equal to D0/10 and at most equal to D0/3.
  19. 19. Tyre (1) according to claim 1, the tread (2) having a surface area void fraction TES equal to the ratio between the total surface area SD of the incisions and the sum of the total surface area SD of the incisions and the total surface area SR of the raised elements defined by these incisions, the surface areas SD and SR being determined in the contact surface area, wherein the surface area void fraction TES is at least equal to 10% at any wear level between a as-new state corresponding to a maximum incision depth D0 and a worn state corresponding to a maximum incision depth DR, wherein said maximum incision depth DR is at least equal to D0/10 and at most equal to D0/3.
  20. 20. Tyre (1) according to claim 1, the tread (2) having a surface area void fraction TES equal to the ratio between the total surface area SD of the incisions and the sum of the total surface area SD of the incisions and the total surface area SR of the raised elements defined by these incisions, the surface areas SD and SR being determined in the contact surface area, wherein the surface area void fraction TES is at most equal to 24% between a as-new condition corresponding to a maximum depth D0 of the incisions and a worn condition corresponding to a maximum depth DR of the incisions, wherein said maximum depth DR of the incisions is at least equal to D0/10 and at most equal to D0/3.

Description

Tire with improved grip for heavy civil engineering vehicles Technical Field The present invention relates to a tyre for heavy vehicles of the construction field type, intended to carry heavy loads and to travel on uneven, multi-stone floors, such as the floors of mines. The invention relates in particular to a tread for such a tire, the grip of which is improved throughout the use of the tire. The invention relates more particularly to a tyre intended to be fitted to a heavy vehicle of the construction site type, such as a dump truck intended for transporting materials mined from quarries or from strip mines. Dump trucks are subjected to particularly severe driving conditions of high load, long lasting speeds, inclined and winding routes, uneven and stony ground. For example, at sites where materials such as ore or coal are mined, the use of dump truck type vehicles includes alternating load-out and idle-return cycles in a simplified form. In the load-out cycle, the load vehicle transports mined material primarily upwardly from a loading zone at the bottom of the mine or pit to an unloading zone, requiring tires with good grip under traction. In the empty return cycle, the empty vehicle returns mainly downwards to the loading zone at the bottom of the mine, so that good tire grip under braking is required. Often the inclined path is also serpentine, thus requiring good lateral grip of the tire. Furthermore, the paths travelled by the vehicles are made of materials typically taken from mines (e.g. crushed and compacted stones) to ensure the integrity of the wearing layers of the paths as the vehicles pass, the stones often being wetted, which means that they are often covered by dirt and water. Thus, on the one hand, it is necessary to make the tread effective in removing this mixture of mud and water to ensure satisfactory grip on muddy ground, and on the other hand, it is also necessary to have a good resistance to abrasion and attack caused by stones present on the ground. Background As described above, the specific use of the dump truck requires special management of the tire mounted thereon. In the new state, the tyre is usually fitted to the front axle or steering shaft of the vehicle. In this front position, the load applied to the tyre is generally estimated to be between 80% and 100% of its nominal load capacity, depending on whether the vehicle is running in an unloaded or loaded state, as defined for example by standard ISO 4250 and the "tyre and rim association" or TRA standard. When the tire reaches about one third of wear (meaning that the initial height of the tread in the new state is reduced by one third), the tire is detached from the front axle and fitted to the rear axle or driven axle of the vehicle. In this rear position, the load applied to the tyre is generally estimated to be between 25% and 100% of its nominal load capacity, depending on whether the vehicle is running in an unloaded or loaded state. Finally, according to current practice, the tyre is permanently removed from the driven shaft when the tread of the tyre reaches a residual height corresponding to the state of complete wear. The tire tread intended to constitute the outer peripheral portion of the tire includes at least one rubber-based material, and is intended to wear upon contact with the ground via the tread surface. The following definitions apply hereinafter: radial direction-a direction perpendicular to the axis of rotation of the tyre, An axial or transverse direction parallel to the axis of rotation of the tyre, A circumferential or longitudinal direction, a direction tangential to the outer circumference of the tyre and perpendicular to the radial and axial directions respectively, An equatorial or intermediate circumferential plane, a plane containing the radial and circumferential directions, which is perpendicular to the rotation axis of the tyre and divides the tyre into two equal parts. The geometry of the tread integrated into the tire is generally characterized by an axial width L along the axial direction and a radial thickness E along the radial direction. The axial width L is defined as the axial width of the tread surface portion in contact with a flat ground, on which the tire is mounted on a recommended rim and subjected to given pressure and load conditions. Conventionally, the radial thickness E is defined as the maximum depth Dmax measured in the incision. In the case of tyres in the new state for vehicles of the construction field type, the axial width L is for example at least equal to 600mm, the maximum depth Dmax is at least equal to 60mm, or even 70mm. However, these characteristics of the axial width L and the maximum depth Dmax depend on the wear state of the tire. In particular, the maximum depth Dmax varies between an initial depth D0 in the new state of the tire and a remaining depth DR in the worn state of the tire (at which value the tire is removed from the vehicle according to cu