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
  • B60C11/02—Replaceable treads
• • 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
  • B60C11/0041—Tyre tread bands; Tread patterns; Anti-skid inserts comprising different tread rubber layers
  • B60C11/005—Tyre tread bands; Tread patterns; Anti-skid inserts comprising different tread rubber layers with cap and base layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D30/00—Producing pneumatic or solid tyres or parts thereof
  • B29D30/06—Pneumatic tyres or parts thereof (e.g. produced by casting, moulding, compression moulding, injection moulding, centrifugal casting)
  • B29D30/52—Unvulcanised treads, e.g. on used tyres; Retreading
  • B29D30/54—Retreading
• • 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
  • B60C2200/00—Tyres specially adapted for particular applications
  • B60C2200/06—Tyres specially adapted for particular applications for heavy duty vehicles

Definitions

• the present invention relates to a tire with a radial carcass reinforcement and more particularly a tire intended to equip vehicles carrying heavy loads, such as, for example, trucks, tractors, trailers or road buses.
• the triangulation ply may also comprise a layer of wires or metal cables with low extensibility forming an angle of between 45° and 90° with the circumferential direction, this so-called triangulation ply being radially located between the carcass reinforcement and the first ply of so-called working vertex, formed of parallel wires or cables presenting angles at most equal to 45° in absolute value.
• the triangulation ply forms with at least said working ply a triangulated reinforcement, which presents, under the various stresses which it undergoes, few deformations, the triangulation ply having the essential role of taking up the transverse compression forces of which is the object all the reinforcing elements in the crown area of the tire.
• Cables are said to be inextensible when said cables have, under a tensile force equal to 10% of the breaking force, a relative elongation at most equal to 0.2%.
• Cables are said to be elastic when said cables have, under a tensile force equal to the breaking load, a relative elongation at least equal to 3% with a maximum tangent modulus of less than 150 GPa.
• the circumferential direction of the tire, or longitudinal direction is the direction tangent to the periphery of the tire and defined by the rolling direction of the tire.
• the axis of rotation of the tire is the axis around which it rotates in normal use.
• a radial or meridian plane is a plane which contains the axis of rotation of the tire.
• the median circumferential plane, or equatorial plane is a plane perpendicular to the axis of rotation of the tire and which divides the tire into two halves.
• the transverse or axial direction of the tire is parallel to the axis of rotation of the tire. An axial distance is measured along the axial direction.
• the expression “axially interior to, respectively axially exterior to” means “whose axial distance measured from the equatorial plane is less than, respectively greater than”.
• the radial direction is a direction intersecting the axis of rotation of the tire and perpendicular thereto. A radial distance is measured along the radial direction.
• the tread that is to say the part of the tire intended to come into contact with the ground during rolling and to wear out during rolling, with a sculpture formed of 'elements in relief delimited by cutouts such as grooves, whether of circumferential, transverse or oblique orientation.
• the purpose of such a tread pattern is to give the tread good driving performance on dry pavement and on pavement covered with water, particularly in rainy weather.
• a cutout of longitudinal orientation is a cutout whose mean plane of at least part of the walls of said cutout forms an angle with a longitudinal plane of less than 10°. This angle formed with a longitudinal plane can be oriented in one direction or the other with respect to said longitudinal plane. A longitudinally oriented cutout can also be a cutout whose walls undulate or zigzag around a mean plane as just described.
• a cutout of transverse orientation is a cutout whose mean plane of at least part of the walls of said cutout forms an angle with a radial plane of less than 35°. This angle formed with a radial plane can be oriented in one direction or the other with respect to said radial plane.
• a cutout of transverse orientation can also be a cutout whose walls undulate or zigzag around a mean plane as just described.
• a cutout of oblique orientation is a cutout whose mean plane of at least part of the walls of said cutout forms an angle with a radial plane comprised between 35° and 80°. This angle formed with a radial plane can be oriented in one direction or the other with respect to said radial plane.
• a cutout oblique orientation can also be a cutout whose walls undulate or zigzag around a mean plane as just described.
• Partial wear of a tread means a state of wear corresponding to a thickness of tread at most equal to the total thickness of tread that can be worn before having to change the tire, in particular for regulatory reasons. .
• the grooves generally include wear indicators, small platforms of vulcanized rubber mixture covering the bottom of these grooves over a certain circumferential length, said indicator indicating the minimum tread depth which must legally remain on the tread. in use.
• the treads for heavy goods vehicles are regroovable (operation by which new grooves can be regrooved), and the tires having such treads carry on their sidewalls the English mention "Regroovable” or the symbol "U”. Regrooving makes it possible on the one hand to prolong the grip potential of the truck tire and on the other hand to significantly increase the mileage performance.
• the regrooving of truck tires is a usual operation authorized for safety and the increase in yield that it entails.
• Fadite blade bound to a frame that rests on the tread surface, can be used manually so as to follow the course of the groove on the surface of the tread fairly closely, even in the case of a groove with a non-straight course .
• Regrooving makes it possible to restore sharp edges and is usually intended to restore a tread height corresponding to that of a half-worn truck tire.
• the usual recommendations aim for a height after regrooving of 5 to 6 mm made up of a regrooving of 3 to 4 mm and a remaining height of 2 mm; in practice, regrooving is often carried out earlier with remaining heights of between 4 and 5 mm leading to a height after regrooving of 7 to 9 mm, for tread heights of tires in new condition of between 12 and 20 mm.
• Regrooving a tire has several advantages. First of all, by restoring tread height to the tyre, regrooving extends the life of the tyre.
• the regrooving being carried out when the thickness of the tread is the smallest and therefore when the tire has the lowest rolling resistance, the distance traveled is extended when the rolling resistance is the lowest. .
• the inventors have set themselves the task of being able to provide tires with performance in terms of further improved rolling resistance while maintaining an ever greater rolling distance and good grip properties on wet ground.
• a tire which can be regrooved at least once, comprising a crown reinforcement, itself covered radially by a tread, consisting of at least one elastomeric compound, joined with two beads via two sidewalls, said tread comprising at least one regroovable groove forming at least one tread pattern element constituting the tread pattern of the tire, having a height between the bottom of said at least one groove and the surface of bearing when the tire is new.
• the height of said at least one regrooved groove is greater than or equal to 70% of the groove height of said at least one regroovable groove of the tire when new.
• the groove height is measured in a meridian section of the tire and corresponds to the distance measured between the radially outer surface of the tread, forming the contact surface with the ground and extrapolated for disregarding the cutouts, and the surface of the tread bottoms, said distance being measured along a direction normal to the radially outer surface of the tread.
• the tread bottoms are the radially innermost points of the recessed areas on the tread, disregarding the presence of elements such as wear indicators, regrooving depth indicator wells or any other element whose sum of surfaces is less than 15% of the total surface of the cutout.
• the groove height of said at least one regroovable groove of the tire when new is thus measured on a new tire.
• the height of said at least one regrooved groove can be measured in the same way when the tire is regrooved; the height of said at least one regrooved groove can also be determined as explained previously from the new tire and the regrooving diagram supplied by the manufacturer.
• the height corresponding to the distance between the running surface in new condition and the bottom of the grooves after the last regrooving is greater than or equal to 200% of the height H N between the bottom of the groove and the running surface when the tire is new.
• the height corresponding to the distance between the running surface in new condition and the bottom of the grooves after the last regrooving is greater than or equal to 250% of the height H N between the bottom of the groove and the surface of bearing when the tire is new.
• the inventors have been able to demonstrate that the combination of a tread thickness substantially identical to that of a tire of more usual design with reduced groove heights when new in comparison with those of tires of a more usual design makes it possible to significantly increase performance in terms of rolling resistance.
• the regrooving provided for tires of more usual design leads to groove heights less than half the height of the grooves when new.
• the regrooving of the tread must therefore probably be carried out more quickly, that is to say for less wear of the tread than in the case of a tire of more usual design.
• the tires according to the invention can be provided with a tread in new condition having a greater thickness than that of conventional tires and lead to performance in terms of rolling resistance that is substantially identical to those of said usual tires associated with a much greater mileage, the tire according to the invention moreover maintaining satisfactory performance in terms of grip on wet ground until the tire is completely worn.
• the thicker tread offers more material to wear and therefore a greater potential mileage.
• the design of the tire according to the invention limits the deformations of the tread and allows to obtain performance in terms of rolling resistance substantially equivalent to that of said tires of more usual design.
• said at least one regroovable groove is circumferential.
• said at least one regroovable groove is transverse.
• said at least one regroovable groove is oblique.
• the invention advantageously provides that all the grooves of the tire are regrooved according to the invention during the same step.
• the height of said at least one regrooved groove is greater than or equal to 85% of the height of said at least one regroovable groove of the tire when new and of preferably even greater than 95% of the tread height of the tire when new.
• at least one groove can be regrooved at least twice. According to this embodiment, it may still be possible to increase rolling resistance performance by providing further reduced groove depths when new while satisfying wet grip performance.
• the invention advantageously provides that all the grooves of the tire are regrooved simultaneously during each regrooving.
• the elastomeric mixture regrooved during the first regrooving is different from the elastomeric mixture regrooved during the second regrooving.
• the radially innermost elastomeric blend contains no black-like filler to display color contrast when it appears on first regroove.
• the tread comprises depth indicators, for example in the form of wells or incisions of small non-zero width placed at the bottom of the groove either parallel to the direction of said groove, either perpendicular to said direction, or both simultaneously, the means indicating the minimum and maximum depths then being the geometric shape of the bottom of the depth indicating incision.
• the regroovable elastomeric mixture is different from at least part of the elastomeric mixture constituting the strip of rolling.
• Such an embodiment can be obtained by co-extrusion of the mixtures during the preparation of the semi-finished product or products intended to constitute at least part of the tread.
• One or other of the embodiments of the invention presented above can also be associated with the production of a complex tread, for example consisting of at least two layers of radially superimposed elastomeric compounds.
• the crown reinforcement of the tire is formed of at least two working crown layers of inextensible reinforcing elements, crossed from one layer to the other by making with the circumferential direction of the angles between 10° and 45°.
• the crown reinforcement also comprises at least one layer of circumferential reinforcement elements.
• An embodiment of the invention further provides that the crown reinforcement is completed radially on the outside by at least one additional layer, called protection, of so-called elastic reinforcing elements, oriented with respect to the circumferential direction. with an angle between 10° and 45° and in the same direction as the angle formed by the inextensible elements of the working layer which is radially adjacent to it.
• the crown reinforcement can still be completed, radially inside between the carcass reinforcement and the nearest radially inner working layer. of the said carcass reinforcement, by a triangulation layer of inextensible metallic reinforcement elements in steel forming, with the circumferential direction, an angle greater than 60° and in the same direction as that of the angle formed by the reinforcement elements of the layer radially closest to the carcass reinforcement.
• a triangulation layer of inextensible metallic reinforcement elements in steel forming, with the circumferential direction, an angle greater than 60° and in the same direction as that of the angle formed by the reinforcement elements of the layer radially closest to the carcass reinforcement.
• FIG. 3 a schematic representation of the rolling resistance during wear of a reference tire and two tires according to the invention.
• Figures 1 and 2 are not shown to scale to simplify understanding.
• Figures 1 and 2 represent only a half-view of a tire which extends symmetrically with respect to the axis XX' which represents the median circumferential plane, or equatorial plane, of a tire.
• the tire 1, of dimension 315/70R22.5 comprises a radial carcass reinforcement 2 anchored in two beads, around bead wires, not shown.
• the carcass reinforcement 2 is formed from a single layer of metal cables.
• the carcass reinforcement 2 is shrunk by a crown reinforcement 5, itself topped with a tread 6.
• the tread has three grooves 3 forming four ribs 4 and the two ribs axially in the center are cut out by through oblique grooves not shown in Figures 1 and 2.
• the crown reinforcement 5 is formed radially from the inside to the outside: - of a first working layer 51 formed of inextensible metal cables, continuous over the entire width of the tablecloth, oriented at an angle al, a layer of circumferential reinforcement elements 53 formed of metal cables in elastic steel 21.23, with a pitch of 2 mm, and a second working layer 52 formed of inextensible metal cables, continuous over the entire width of the ply, oriented at an angle a2 and crossed to the metal cables of the first working layer.
• a first working layer 51 formed of inextensible metal cables, continuous over the entire width of the tablecloth, oriented at an angle al
• a layer of circumferential reinforcement elements 53 formed of metal cables in elastic steel 21.23, with a pitch of 2 mm
• a second working layer 52 formed of inextensible metal cables, continuous over the entire width of the ply, oriented at an angle a2 and crossed to the metal cables of the first working layer.
• the axial width L 51 of the first working layer 51 is equal to 246 mm.
• the axial width L 52 of the second working layer 52 is equal to 228 mm.
• the grooves 3 are regroovable type. As illustrated in Figure 1, the grooves 3 consist of a single layer A forming the bottom of the grooves when new and corresponding to a single regrooving.
• the height on a new tire H N 3 of the grooves 3 is equal to 7.5 mm.
• the height H R of the grooves 3 after regrooving is equal to 9.5 mm and therefore represents 127% of H N 3.
• This height H R corresponds to a regrooving of 7.5 mm when there remains a height of the initial groove of 2 mm, a value close to the generally authorized legal limit corresponding to the minimum height and corresponding to the wear indicators. This limit is symbolized by line 7 in Figure 1.
• the non-measurable height before this regrooving and corresponding to the distance between the running surface in new condition and the bottom of a groove 3 after regrooving is thus equal to 15 mm.
• the ratio of this non-measurable height equal to 15 mm to the height H N 3 is equal to 2 and therefore much greater than or equal to 200%.
• the height HR, measured after regrooving, and the non-measurable height before regrooving and corresponding to the distance between the running surface in new condition and the bottom of a groove 3 after regrooving can also be determined on a new tire from the regrooving diagrams provided by the manufacturer as explained above.
• Figure 2 illustrates a tire whose grooves 23 can be regrooved twice.
• the grooves 23 are made up when new of two layers B and C forming the bottom of the grooves when new and corresponding to these two regroovings.
• the height on a new tire H N 23 of the grooves 23 is equal to 6 mm.
• the height H RI of the grooves 23 after the first regrooving is equal to 7 mm and therefore represents 117% of H N 23. [0070]
• This height H RI corresponds to a regrooving of 5 mm when there remains a height of the initial groove of 2 mm, a value close to the generally authorized legal limit corresponding to the minimum height and corresponding to the wear indicators. This limit is symbolized by line 71 in Figure 2.
• the non-measurable height before a first regrooving and corresponding to the distance between the running surface when new and the bottom of the groove after the first regrooving is thus equal to 11 mm.
• the height H RI measured after the first regrooving, and the non-measurable height before a first regrooving and corresponding to the distance between the running surface in new condition and the bottom of the groove after the first regrooving can also be determined on a new tire from the regrooving diagram provided by the manufacturer, as explained above.
• the height H R 2 of the grooves 23 after the second regrooving is equal to 6 mm and therefore represents 100% of H N 23. And the height H R 2 of the grooves 23 after the second regrooving represents 86% of H RI .
• This height H R 2 corresponds to a regrooving of 4 mm when there remains a height of the groove of 2 mm, a value close to the generally authorized legal limit. corresponding to the minimum height. This limit is symbolized by line 72 in Figure 2.
• the non-measurable height before the two regroovings and corresponding to the distance between the running surface when new and the bottom of the grooves 23 after the second regrooving is thus equal to 15 mm.
• the ratio of this non-measurable height equal to 15 mm to the height H N 23 is equal to 2.5 and therefore much greater than or equal to 200%.
• the height H R 2 measured after the second regrooving, and the non-measurable height before the two regroovings and corresponding to the distance between the running surface when new and the bottom of the grooves after the second regrooving can also be determined on a new tire from the regrooving diagram provided by the manufacturer, as explained above.
• the tire thus shown in FIG. 2 provides two regroovings at different stages of tire wear.
• the grooves are regrooved simultaneously at each regrooving step.
• the regrooving of the various grooves of a tire can be provided to be done staggered over time.
• the tire may comprise a part of these grooves which can be regrooved once and other grooves which can be regrooved several times.
• a tire could thus comprise a combination of grooves such as those illustrated in FIG. 1 and of grooves such as those illustrated in FIG. 2.
• Tires have been produced on the basis of the elastomeric mixture described below as the mixture constituting the tread.
• the height, measured after a first regrooving, and the non-measurable height before regrooving and corresponding to the distance between the running surface in new condition and the bottom of the grooves after the can also be determined on a new tire from the regrooving diagrams provided by the manufacturer.
• Tires T1 and T2 are produced in accordance with the invention.
• the tire T1 conforms to the representation in FIG. 1.
• the tire T2 conforms to the representation in FIG. 2.
• Rolling resistance measurements were also carried out on each of the tires under identical running conditions according to Regulation No. 117 of the Economic Commission for Europe of the United Nations (UNECE). The results of the measurements are presented in the following table, a value of 100 being assigned to tire R in new condition. A value of 90 means that the rolling resistance coefficient is reduced by 10% and corresponds to a higher rolling resistance performance. Measurements are taken on a new tire and on a planed tire to bring it to the level of the usual wear limit of approximately 2 mm on each of the tires R, T1 and T2.
• a measurement is again taken after regrooving on each of the tires R, T1 and T2 and another on each of the tires R, T1 and T2 again planed to be brought to the level of the usual wear limit of approximately 2 mm.
• Tire T2 is still measured after the second regrooving and a final measurement is carried out on this tire T2 after planing to bring it to the level of the usual wear limit of approximately 2 mm.
• FIG. 3 schematically illustrates a representation of the evolution of the rolling resistance of each of the tires R, T1 and T2 from their new state until their end of life, that is to say during the 13 mm d tread wear.
• FIG. 3 represents, on the ordinate, the measured or estimated value of the rolling resistance of the tire as a function of the height of tread worn, on the abscissa, this height starting from 0 and ending at 13 mm.
• the 13 mm correspond to the 15 mm of the tread provided for each of the tires R, T1 and T2, taking into account the 2 mm retained at the end of the life of the tires, a value close to the generally authorized legal limit.
• the three lines appearing in this figure 3 correspond to each of the tires R, T1 and T2.
• the calculation of the surfaces defined by these three lines makes it possible to estimate the average rolling resistance during use of each of these tyres.
• the results showed that tire T1 allows a gain of 7% compared to tire R and that tire T2 allows a gain of 14% compared to tire R.

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

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• 2021
  • 2021-02-25 FR FR2101845A patent/FR3120011B1/fr active Active
• 2022
  • 2022-02-17 EP EP22710423.9A patent/EP4297983A1/de active Pending
  • 2022-02-17 US US18/277,789 patent/US20240227452A9/en active Pending
  • 2022-02-17 WO PCT/FR2022/050287 patent/WO2022180325A1/fr active Application Filing

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