Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/03—Tread patterns
  • B60C11/032—Patterns comprising isolated recesses
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/03—Tread patterns
  • B60C11/032—Patterns comprising isolated recesses
  • B60C11/0323—Patterns comprising isolated recesses tread comprising channels under the tread surface, e.g. for draining water
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/03—Tread patterns
  • B60C11/0306—Patterns comprising block rows or discontinuous ribs
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/03—Tread patterns
  • B60C11/0306—Patterns comprising block rows or discontinuous ribs
  • B60C11/0309—Patterns comprising block rows or discontinuous ribs further characterised by the groove cross-section
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/03—Tread patterns
  • B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
  • B60C11/1236—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special arrangements in the tread pattern
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/03—Tread patterns
  • B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
  • B60C11/1259—Depth of the sipe
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/03—Tread patterns
  • B60C2011/0337—Tread patterns characterised by particular design features of the pattern
  • B60C2011/0339—Grooves
  • B60C2011/0341—Circumferential grooves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/03—Tread patterns
  • B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
  • B60C11/1236—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special arrangements in the tread pattern
  • B60C2011/1245—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special arrangements in the tread pattern being arranged in crossing relation, e.g. sipe mesh
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C2200/00—Tyres specially adapted for particular applications
  • B60C2200/06—Tyres specially adapted for particular applications for heavy duty vehicles

Definitions

• the subject of the present invention is a tire tread for a heavy-duty vehicle intended to run on paved roads.
• a tread located at the periphery of the tire and intended to be worn when it comes into contact with the ground via a tread surface, is made up of at least one rubber-based material. . It also includes a tread pattern which is a combination of cutouts, or hollows, and elements in relief, intended to ensure satisfactory grip performance, more particularly on wet road surfaces.
• a tread can be defined geometrically by three dimensions: a smaller dimension in a radial direction, or thickness, an intermediate dimension in a transverse direction, or width, and a larger dimension in a longitudinal direction, or length.
• the thickness is the distance, measured in a radial direction, between the running surface and a bottom surface, defined as a surface parallel to the running surface and tangent to the deepest cutout.
• the width is the distance between the transverse ends of the running surface.
• the length is equal to the outer circumference of the tire.
• a tread is often characterized by a volume indentation rate, defined as the ratio between the void volume and the total volume of the tread, this total volume being measured between the running surface and the surface. background without taking into account the dips.
• the rate of indentation by volume is generally between 10% and 25%, for a tire in new condition, before running.
• the inventors have also set themselves the objective of improving the resistance to tearing of oblique incisions opening out into the outer cavities of the tread of a tire for heavy goods vehicles, in particular in those with complex cutouts.
• each external cavity being connected to two substantially longitudinal incisions, extending along the average trace of the substantially longitudinal cutout and cutting the outline at two connection points,
• each oblique incision forming an angle strictly greater than 90°, with at least two straight lines tangent to the contour respectively at two points of the contour, positioned on either side of the average trace of the oblique incision and at a curvilinear distance from the connection point at most equal to 2 mm.
• the average trace of each oblique incision forms an angle strictly greater than 90°, with any straight line tangent to the contour at any point of the contour positioned at a curvilinear distance from the connection point at most equal to 2 mm.
• no tangent to the contour at a point in the vicinity of the connection point can form an acute angle, which implies that the inventors aim, in this embodiment, a total absence of tearing of the tread, even very localized and of small size.
• the width of the emerging section of each external cavity is at least equal to 4 mm. Consequently, the length of the emerging section of each external cavity is also at least equal to 4 mm. Below 4 mm, the water storage capacity of the external cavity, when driving on wet ground, is insufficient to guarantee sufficient grip of the tire.
• the width of the emerging section of each external cavity is at most equal to 17 mm. Above 17 mm, the probability of appearance of irregular wear patterns on the contour of the external cavity becomes high.
• each external cavity has a depth, measured between the running surface and a bottom of the cavity, at least equal to 0.25 times the thickness of the tread.
• the depth of the external cavity is the distance measured between the through section and the bottom of the external cavity, more precisely between the deepest point of the external cavity and its orthogonal projection on the running surface.
• Tread thickness is the distance measured from the running surface to the bottom surface, parallel to the running surface and tangent to the bottom of the deepest cutout, specifically between the point of tangency of the surface bottom with the bottom of the deepest cutout and its projection on the running surface.
• the depth of the external cavity is insufficient to guarantee the water storage capacity of the external cavity, in the event of rolling on wet ground, sufficient vis-à-vis vis of suitable grip of the tyre.
• each external cavity has a depth, measured between the tread surface and a cavity bottom, at most equal to the thickness of the tire tread. rolling. Above this value, the depth of the external cavity leads to a reduction in the thickness of the rubber-based layer, interposed between the bottom surface and the crown reinforcement of the tire, and increases the risk of damage. mechanical aggression of the crown reinforcement by external objects.
• each oblique incision has a thickness, measured between the two walls which delimit it, at least equal to 0.2 mm.
• This minimum value corresponds to a technological minimum linked to the manufacturing technology of the incision by molding using a generally metallic mold strip.
• each oblique incision has a thickness, measured between the two walls which delimit it, at most equal to 1.2 mm. Above this value, the coming into contact of the portions of material on either side of the incision is no longer guaranteed, resulting in local deformations on either side of the incision resulting in increased rate of tread wear.
• each oblique incision has a depth, measured between the running surface and an incision bottom, at least equal to 2 mm. Below 2 mm, the edge effect provided by the incision is insufficient to guarantee good grip, an edge being the intersection of a wall delimiting the incision with the running surface.
• each oblique incision has a depth, measured between the tread surface and an incision bottom, at most equal to the depth of the external cavity. Above this value, the portions of material delimited by the incision become too flexible, which can increase the risk of local tearing.
• the first straight line, along which the length of the emerging section of each external cavity is measured is parallel to a longitudinal direction of the tread and the second straight line, along which the width of the the open section of each external cavity is parallel to a transverse direction of the tread.
• the longitudinal direction is the preferential direction of alignment of the external cavities, according to their largest dimension, because it corresponds to the direction of rolling and therefore of preferential flow of the water.
• the tread comprises at least two substantially longitudinal cutouts, at least one of which is a complex cutout comprising an alternation of external cavities, open to the tread surface, and of internal cavities, hidden in the thickness of the tread in its new state and connected to the tread surface by a substantially longitudinal incision, said respectively external and internal cavities being interconnected so as to form a continuous channel.
• complex cutouts provide a number of technical advantages as described, for example, in documents WO 2011039194, WO 2011101495 and WO 2012130735.
• Another subject of the invention is a tire for a heavy-duty vehicle comprising a tread according to any one of the embodiments described above.
• - Figure 6 Top view of a tread according to a third embodiment of the invention, comprising a complex longitudinal cutout
• - Figure 7 Cross-sectional view, at the level of an internal cavity, of a tread according to a third embodiment of the invention, comprising a complex longitudinal cutout.
• Figure 1 is a top view of a tread according to a first embodiment of the invention.
• the tread intended to come into contact with the ground via a rolling surface 2, comprises cutouts 3 and elements in relief 4.
• the cutouts 3 there are five longitudinal cutouts, extending in a longitudinal direction XX', and oblique cutouts with respect to the longitudinal direction XX'.
• the longitudinal cutouts we distinguish:
• the mean trace M2 of each oblique incision 92 forms an angle (Al, A2) strictly greater than 90°, with at least at least two straight lines (T1, T2) tangent to the contour 8 respectively at two points (II, 12) of the contour 8, positioned on either side of the average trace M2 of the oblique incision 92 and at a curvilinear distance (dl , d2) of connection point I at most equal to 2 mm.
• Figure 3 is a partial sectional view of a tread according to the first embodiment of the invention, shown in Figure 1.
• the partial section C-C is made along the mean plane of the oblique incision 92 as shown in Figure 2.
• the distance between the running surface 2 and the bottom surface 5 defines the thickness E of the tread.
• bottom surface 5 is a surface parallel to running surface 2 and tangent to the bottom of the deepest cutout (not shown).
• the bottom surface delimits the maximum thickness of material to be worn.
• the external cavity 6 open on the rolling surface 2 along the emerging section 7 has a depth P.
• the oblique incision 92 has a depth PI less than the depth P of the external cavity, itself less than the thickness E of the tread.
• FIG. 4 is a top view of a tread according to a second embodiment of the invention.
• FIG. 4 essentially differs from FIG. 1 by the shape of the external cavities 6, which have curvilinear contours 7, and by the distribution of the oblique incisions 92 in the tread 1.
• the lateral parts and the central part of the tread contain oblique incisions that do not open into the external cavities 6.
• Figure 8 is a cross-sectional view, at the level of an external cavity, of a tread according to the third embodiment of the invention, shown in Figure 6.
• the cross-section is carried out according to the transverse plane II-II, perpendicular to the longitudinal direction XX', of FIG. 6.
• This section shows in particular an external cavity 61, open on the rolling surface 2 and positioned in the median plane of the tread, between the two longitudinal grooves 3 separating the elements 4 in relief with respect to the bottom surface 5.
• the invention was tested for a tire in the size 355/50 R 22.5, intended to carry a load equal to 4000 kg, for an inflation pressure equal to 9 bars, according to the "Standards Manual 2020" of the ETRTO standard.
• the inventors observed tearing suffered by a tread comprising both a first family of emerging oblique incisions, in accordance with the invention with angles obtuse, and a second family of emerging oblique incisions, not in accordance with the invention with acute angles. They found that the initiation of cracks at the junction zones of the oblique incisions with the external cavities essentially concerned the second family of emerging oblique incisions, not in accordance with the invention, but not the first family of emerging oblique incisions, in accordance with the invention. Consequently, they were able to conclude that the resistance to tearing of oblique incisions opening into external cavities was improved, thanks to the choice of an optimized orientation of these incisions.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Tires In General (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=73793497

Family Applications (1)

Country Status (6)

Family Cites Families (8)

• 2020
  • 2020-10-26 FR FR2010963A patent/FR3115497A1/fr active Pending
• 2021
  • 2021-10-22 EP EP21810402.4A patent/EP4232303A1/de active Pending
  • 2021-10-22 BR BR112023006140A patent/BR112023006140A2/pt unknown
  • 2021-10-22 US US18/033,751 patent/US20230398815A1/en active Pending
  • 2021-10-22 WO PCT/FR2021/051853 patent/WO2022090651A1/fr active Application Filing
  • 2021-10-22 CN CN202180071938.0A patent/CN116490384A/zh active Pending

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