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
  • B60C11/0306—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
  • B60C11/0306—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
  • B60C11/032—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
  • B60C11/12—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
  • B60C11/125—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special arrangements in the tread pattern arranged at the groove bottom
• • 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
  • B60C11/1272—Width of the sipe
  • B60C11/1281—Width of the sipe different within the same sipe, i.e. enlarged width portion at sipe bottom or along its length
• • 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
  • B60C2011/0337—Tread patterns characterised by particular design features of the pattern
  • B60C2011/0339—Grooves
  • B60C2011/0341—Circumferential grooves
  • B60C2011/0346—Circumferential grooves with zigzag shape
• • 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
  • B60C2011/0355—Circumferential grooves characterised by depth
• • 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
  • B60C2011/0358—Lateral grooves, i.e. having an angle of 45 to 90 degees to the equatorial plane
• • 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
  • B60C2011/0374—Slant grooves, i.e. having an angle of about 5 to 35 degrees to the equatorial plane
• • 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
  • B60C2011/0374—Slant grooves, i.e. having an angle of about 5 to 35 degrees to the equatorial plane
  • B60C2011/0379—Slant grooves, i.e. having an angle of about 5 to 35 degrees to the equatorial plane characterised by depth
• • 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
  • B60C11/1204—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe
  • B60C2011/1213—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe sinusoidal or zigzag at the tread surface
• • 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 for a heavy vehicle for urban use, such as an urban bus, and relates more particularly to its tread.
• a tread consisting of at least one rubber-based material, is the wearing and adherent part of the tire, positioned at its periphery and intended to be worn when it comes into contact with the ground via of a rolling surface and to guarantee the grip of the tire in its contact with the ground which may be dry or wet.
• the tread generally comprises a sculpture which is a combination of cutouts, or hollows, and elements in relief, of the block type or of the rib type.
• the proportion of cutouts in a tread is usually quantified by a volume indentation rate, defined as the ratio between the volume of cutouts and the total volume of the tread assumed without cutouts, corresponding to the volume geometry bounded by the running surface and a surface tangent to the deepest cutout and parallel to the running surface.
• the volume indentation rate of the tread can reach a low value, typically less than 10%.
• Such a level of volume indentation is possible because, given the low speed of an urban bus, the evacuation of water, possibly present on the ground, by the cutouts of the tread does not require a volume high cutouts.
• the cutouts can be of two types: grooves and incisions.
• the grooves are wide cutouts, essentially allowing the storage and evacuation of any water present on the floor.
• a cutout is said to be wide when it has a thickness such that the walls of material facing it delimiting it do not come into contact with each other, during the passage of the tread in the surface. contact, the tire being subject to recommended inflation and load conditions as defined, for example, by the European standards of the "European Tire and Rim Technical Organization” or “ETRTO” in its “Standards Manual 2020 - Commercial Vehicle Tyres”.
• the incisions are narrow cutouts whose intersections with the running surface or ridges contribute to grip on wet ground, thanks to a ridge effect in contact with the ground which makes it possible to break the film of water present on the floor.
• a cutout is said to be narrow when it has a thickness such that the walls of material facing it delimiting it come into contact at least partially with each other, when the tread passes through the contact surface.
• the cutouts can have different directions and are usually classified as longitudinal, transverse or oblique cutouts.
• a cutout is said to be longitudinal if its average line forms, with the longitudinal direction of the tire, tangent to the running surface in the direction of rotation of the tire, an average angle at most equal to 10°.
• a cutout is said to be transverse if its average line forms, with the transverse direction of the tire, parallel to the axis of rotation of the tire, an average angle at most equal to 10°.
• a cutout is said to be oblique if it is neither longitudinal nor transverse, i.e. if it forms, with the longitudinal direction, an average angle greater than 10° and less than 80°.
• the average line of a cutout is the intersection of the running surface with an average surface of the cutout, perpendicular to the running surface and equidistant from the walls of material delimiting the cutout: it is therefore the trace of the average area of the cutout on the tread surface of the tire.
• the inventors have also set themselves the objective, for a tire for a heavy vehicle for urban use, such as an urban bus, comprising a tread having in particular a low volumetric indentation rate, to further improve grip of the tire on dry and wet surfaces, in order to guarantee the required level of safety.
• This objective has been achieved by a tire for a heavy vehicle for urban use comprising a tread intended to come into contact with the ground via a running surface,
• the tread having a transverse width, measured between two transverse ends of the tread surface, in a transverse direction parallel to an axis of revolution of the tire, and comprising cutouts delimiting elements in relief,
• any cutout being delimited by two walls intersecting the running surface along two edges
• any cut-out having a thickness, measured on the tread surface between the two edges, perpendicular to the two edges, and a depth, measured between the tread surface and a bottom of the cut-out, perpendicular to the tread surface, - each wall forming , in any plane perpendicular to said wall and with the straight line, passing through the edge, intersection of said wall with the running surface, and perpendicular to the running surface, a clearance angle,
• the tread comprising at least two wide cutouts, called grooves, in zigzag and parallel to each other,
• each zigzag groove consisting of an alternation of longitudinal portions, parallel to a longitudinal direction of the tire, and oblique portions, each forming, with the longitudinal direction, the same angle at least equal to 15°, -the depth of each zigzag groove being at least equal to 7 mm
• each wall delimiting each zigzag groove being at least equal to 10°.
• the essential principle of the invention is to provide a tread with a system of cutouts, at least of which are wide and have an oblique general orientation with good efficiency vis-à-vis transverse grip and longitudinal grip.
• wide cutout we mean a cutout whose material walls delimiting it are sufficiently distant from each other so as not to come into contact with each other when rolling, when the cutout passes in contact with the ground: such a wide cutout is usually referred to as a groove. Furthermore, this groove must be sufficiently deep, with a minimum depth equal to 7 mm, to guarantee a volume of storage and evacuation of water potentially present on the ground in the event of rain, and therefore sufficient grip on wet ground.
• the walls delimiting such a groove must be sufficiently inclined, with a so-called draft angle at least equal to 10°, this draft angle being measured in a plane perpendicular to the axis of revolution of the tire and with the straight line, passing through the corresponding edge and perpendicular to the running surface.
• a sufficiently high clearance angle makes it possible to obtain a rigidity of the elements in relief, delimiting the cutout, making it possible to guarantee satisfactory resistance to wear of the tread.
• the two facing walls do not necessarily have the same draft angle value.
• Oblique general orientation means an average direction of the wide groove forming, with the longitudinal direction of the tire, an angle typically greater than 10° and less than 80°.
• the groove has a zigzag shape, consisting of alternating longitudinal portions and oblique portions oscillating around an oblique mean straight line, the oblique portions forming, with the longitudinal direction, an angle at least equal to 10°.
• the longitudinal portions, having longitudinal ridges, are effective with respect to transverse grip.
• the oblique portions have edges having an effective longitudinal component with respect to transverse grip, and an effective transverse component with respect to longitudinal grip.
• a network of such wide oblique grooves is as effective as a network of longitudinal and transverse grooves, with respect to adhesion, with a lower volume of cutouts, therefore a higher volume of material to be worn. It is therefore a particularly interesting system of cut-outs to guarantee good grip of a tread with a low volumetric indentation rate.
• each wall delimiting each zigzag groove is advantageous from the point of view of the assembly of the cooking mold elements, intended for the production of the sculpture, because these can be easily connected to each other at the levels of said portions. longitudinal with great precision.
• the draft angle of each wall delimiting each zigzag groove is at most equal to 25°, because, beyond this angle value, the groove volume becomes too small to guarantee a efficient storage and evacuation of any water present in contact with the ground.
• each oblique portion of each zigzag groove forms, with the longitudinal direction of the tire, an angle at least equal to 30° and at most equal to 45°, preferably at most equal to 40°.
• the transverse component of the oblique portion edges is of limited size and therefore less effective with respect to longitudinal grip. Beyond 45°, the oblique portion has an inclination that does not allow it to emerge at the entry and exit of the contact area, and therefore to channel any water present on the ground, resulting in poorer performance. grip on wet ground.
• each longitudinal portion of each zigzag groove has a longitudinal length, measured on the running surface, in the longitudinal direction of the tire, at least equal to 0.5 * 7r * /120 and at most equal to 2 * n * D/120.
• any first zigzag groove are offset longitudinally with respect to the longitudinal portions of any second zigzag groove, such that any two longitudinal portions respectively of said first zigzag groove and of said second zigzag groove do not simultaneously come into contact with the ground when rolling the tire.
• any transverse straight line passing through a first end of a longitudinal portion of a given first zigzag groove does not pass by no other first end of a longitudinal portion of a second zigzag groove. This implies that the respective longitudinal portions of two zigzag grooves do not come into contact simultaneously. This results in a reduction of the rolling noise generated by the circulation of air in said zigzag grooves.
• no zigzag groove opens at a transverse end of the running surface.
• the most transversely outer longitudinal portions of the zigzag grooves are positioned, with respect to a median circumferential plane of the tire, at a distance at most equal to 40% of the transverse width of the tread.
• each continuous rib at the edge of the tread therefore has a sufficient width to resist tearing, resulting, for example, from impacts of the tire against the pavements, which are frequent in urban use.
• At least one of the zigzag grooves is extended radially inwards, from its cutout bottom, by an incision.
• Such a zigzag groove, extended radially inwards by an incision, is said to be stepped.
• an incision is a thinner cutout a groove and the walls of which are intended to come into contact at least partially with each other, when rolling.
• the incision therefore appears on the running surface after a certain level of wear of the tread.
• a stepped groove due to the presence of an incision extending it into the thickness of the tread, allows greater mobility of the elements of material in relief that it delimits, and therefore contributes to easier flattening of the unwinding belt, which limits slippage in the contact and therefore slows down wear. Easier flattening of the tread is also favorable to a reduction in rolling resistance.
• a stepped groove guarantees the presence of two facing edges during wear - first that of the radially outer groove, then those of the radially inner incision -, hence a durability of grip over the life of the tyre.
• This incision because of its thinness, has little impact on the volume of cutouts, and therefore the volume notching rate: consequently, it has no significant impact on the wear life.
• the tread comprises at least one incision opening onto the running surface and parallel to the at least two zigzag grooves.
• said at least one incision is extended radially inwards by a groove.
• Such a zigzag incision, extended radially inwards by a groove, is said to be stepped.
• a groove is a cutout of greater thickness than an incision and whose walls are intended not to come into contact with each other when driving.
• the groove therefore appears on the running surface after a certain level of wear of the tread.
• a stepped incision, due to the presence of a groove extending it in the thickness of the tread, makes it possible to increase the volume of cutouts on the surface, after a certain level of wear, allowing to find a capacity of storage and evacuation of water. It thus makes it possible to compensate for the loss of storage capacity of a stepped groove which becomes an incision during wear.
• such a groove radially interior to an incision emerging at the surface has walls having a minimum clearance angle of 10° and a minimum width at the bottom of the groove of 2 mm.
• the tread having a volume indentation rate, defined as the ratio between the volume of cutouts and the total volume of the tread assumed to be without cutouts, corresponding to the geometric volume delimited by the tread surface and a surface tangent to the deepest cutout and parallel to the tread surface, the volume indentation rate is at most equal to 10%, to satisfy the targeted lifetime performance.
• the tire according to one of the preceding embodiments of the invention comprising a crown reinforcement comprising at least two working layers consisting of reinforcements coated in a rubber mixture and crossed from one working layer to the next. , the reinforcements of each of the at least two working layers form, with the longitudinal direction of the tire, an angle at least equal to 15° and at most equal to 35°.
• the crown reinforcement comprises at least one hooping layer consisting of reinforcements coated in a rubber compound, parallel to the longitudinal direction of the tire, and radially interposed between two layers of work.
• - Figure 2 Sectional view of a tread of a tire for an urban bus according to the invention, according to a section plane CC' perpendicular to the axis of rotation of the tire,
• Figure 1 is a top view of a tread 2 of a tire 1 for a city bus according to the invention.
• the tread 2 intended to come into contact with the ground via a tread surface 3, has a transverse width W, measured between two transverse ends 21 of the tread surface 3, in a transverse direction YY 'Parallel to an axis of revolution of the tire.
• the tread 2 comprises cutouts 4 delimiting elements in relief 5. Any cutout 4 is delimited by two walls intersecting the rolling surface 3 along two edges 7, and has a thickness E, measured on the rolling surface 3 between the two edges 7, perpendicular to the two edges 7.
• the tread 2 comprises at least two wide cutouts, called grooves, zigzag 41 and parallel to each other.
• Each zigzag groove 41 oscillating around a straight line T'T', consists of alternating longitudinal portions 411, having a circumferential length L, parallel to a longitudinal direction XX' of the tire, and oblique portions 412, forming each, with the longitudinal direction XX', the same angle A at least equal to 15°.
• no zigzag groove 41 opens at the level of a transverse end 21 of the running surface 3.
• the tread comprises an incision 43 opening on the running surface 3, interposed between two consecutive zigzag grooves 41, and parallel to said zigzag grooves 41. 'cutting all the zigzag cutouts (41, 42) of the tread, as shown in Figure 1.
• the tire comprises a crown reinforcement 9 comprising at least ns two working layers (91, 92) consisting of reinforcements coated in a rubber mixture and crossed from one working layer to the next.
• the crown reinforcement 9 also comprises a hooping layer 93 consisting of reinforcements coated in a rubber compound, parallel to the longitudinal direction of the tire, and radially interposed between the two working layers (91, 92).
• Figure 3 is a sectional view of a zigzag groove 41, perpendicular to said zigzag groove 41 and extended radially inwards by an incision 43.
• the zigzag groove 41 is delimited by two walls 6 cutting the rolling surface 3 along two edges 7. It has a thickness E, measured on the rolling surface 3 between the two edges 7, perpendicular to the two edges 7, and a depth P, measured between the rolling surface 3 and a bottom of cut-out 8, perpendicular to running surface 3.
• Each wall 6 forms, in any plane perpendicular to said wall 6 and with line NN', passing through edge 7, the intersection of said wall 6 with running surface 3 , and perpendicular to the running surface 3, a draft angle (DI, D2).
• the depth P of each zigzag groove 41 is at least equal to 7 mm and the draft angle (DI, D2) of each wall 6 delimiting each zigzag groove 41 is at least equal to 10°.
• FIG. 4 is a sectional view of a zigzag incision 42, perpendicular to said zigzag incision 42 and extended radially inwards by a groove 44.
• FIG. 5 is a diagram of the respective orientations of the zigzag grooves 41 and of the reinforcements of the respectively working (91, 92) and hooping (93) layers of the crown reinforcement 9 of a tire according to the invention, as represented in FIG. 2.
• the reinforcements (910, 920) of each of the two working layers (91, 92) form, with the longitudinal direction (XX') of the tire, an angle (B1, B2) at least equal to 15° and at most equal to 35°, the reinforcements 930 of the hooping layer 93 being, by definition, parallel to the longitudinal direction XX'.
• the invention has been more particularly studied for a tire of size 275/70R22.5 X Incity Michelin, intended to equip an urban bus.
• the recommended inflation pressure is equal to 9 bars
• the recommended static load is equal to 3550 kg
• the maximum recommended speed is equal to 100 km/h.

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

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (5)

Citations (3)

Family Cites Families (8)

• 2021
  • 2021-09-10 FR FR2109489A patent/FR3126923B1/fr active Active
• 2022
  • 2022-09-05 WO PCT/FR2022/051665 patent/WO2023037064A1/fr not_active Ceased
  • 2022-09-05 CN CN202280060371.1A patent/CN117916105A/zh active Pending
  • 2022-09-05 US US18/688,214 patent/US20250001809A1/en active Pending
  • 2022-09-05 EP EP22783362.1A patent/EP4399104A1/de active Pending

Patent Citations (3)

Non-Patent Citations (1)

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