WO2019133009A1 - Pneu à performance de résistance au roulement améliorée - Google Patents

Pneu à performance de résistance au roulement améliorée Download PDF

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Publication number
WO2019133009A1
WO2019133009A1 PCT/US2017/069139 US2017069139W WO2019133009A1 WO 2019133009 A1 WO2019133009 A1 WO 2019133009A1 US 2017069139 W US2017069139 W US 2017069139W WO 2019133009 A1 WO2019133009 A1 WO 2019133009A1
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WO
WIPO (PCT)
Prior art keywords
tread
tire
lateral
elongate
depth
Prior art date
Application number
PCT/US2017/069139
Other languages
English (en)
Inventor
Patrick Jon Buresh
Jason SCHOENMAKER
Robert Dillon
Phillip William Check
William Marshall Thompson
Original Assignee
Compagnie Generale Des Etablissements Michelin
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Compagnie Generale Des Etablissements Michelin filed Critical Compagnie Generale Des Etablissements Michelin
Priority to PCT/US2017/069139 priority Critical patent/WO2019133009A1/fr
Publication of WO2019133009A1 publication Critical patent/WO2019133009A1/fr

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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
    • B60C11/0041—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
    • 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
    • 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
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/0007—Reinforcements made of metallic elements, e.g. cords, yarns, filaments or fibres made from metal
    • 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
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C2009/0071—Reinforcements or ply arrangement of pneumatic tyres characterised by special physical properties of the reinforcements
    • B60C2009/0085—Tensile strength
    • 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
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
    • B60C9/1835—Rubber strips or cushions at the belt edges
    • B60C2009/1857—Rubber strips or cushions at the belt edges radially above the belt plies
    • 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
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/18—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers
    • B60C9/20—Structure or arrangement of belts or breakers, crown-reinforcing or cushioning layers built-up from rubberised plies each having all cords arranged substantially parallel
    • B60C2009/2061—Physical properties or dimensions of the belt coating rubber
    • B60C2009/2064—Modulus; Hardness; Loss modulus or "tangens delta"
    • 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
    • B60C11/0008—Tyre tread bands; Tread patterns; Anti-skid inserts characterised by the tread rubber
    • B60C2011/0016—Physical properties or dimensions
    • B60C2011/0025—Modulus or tan delta
    • 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
    • B60C2011/129—Sipe density, i.e. the distance between the sipes within the pattern
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/80—Technologies aiming to reduce greenhouse gasses emissions common to all road transportation technologies
    • Y02T10/86—Optimisation of rolling resistance, e.g. weight reduction 

Definitions

  • Embodiments of this disclosure relate generally to pneumatic tires.
  • Embodiments of the disclosure include a pneumatic tire.
  • the tire comprises: a pair of annular bead areas spaced apart axially along a rotational axis of the tire; a pair of sidewalls spaced apart axially along the rotational axis of the tire, each sidewall of the pair of sidewalls extending outwardly in a radial direction from one bead area of the pair of bead areas relative to the rotational axis; and, a crown portion arranged widthwise between the pair of sidewalls and extending annularly around the tire.
  • the crown portion includes a tread formed of elastomeric material arranged annularly around the crown portion and forming an outer, ground-engaging side upon which the tire is intended to roll upon, the tread having a thickness extending radially and a width extending axially, the tread forming a wearing portion the tire.
  • the crown portion further includes one or more belt plies each forming a layer of elastomeric material reinforced with a plurality of elongate reinforcements spaced apart in an array, the one or more belt plies being arranged radially inward and below the tread.
  • the crown portion further includes a pair of shoulders, each shoulder forming a portion of the crown arranged adjacent to each sidewall.
  • the crown portion further includes a cap ply arranged radially outward from the one or more belt plies and between the tread and the one or more belt plies, the cap ply extending at least partially across a full width of at least one of the belt plies and being arranged at least partially within each shoulder, the cap ply forming a layer of elastomeric material reinforced with a plurality of elongate reinforcements spaced apart in an array, the cap ply being characterized as having a rupture force greater than 210 N per 15 mm of the cap ply width.
  • the crown portion further includes an inner layer of elastomeric material free of any elongate reinforcements, the inner layer arranged radially inward from the tread between the tread and the one or more belt plies and cap ply, the inner layer being substantially formed of elastomeric material characterized as having a hysteresis lower than a hysteresis of the elastomeric material forming the tread.
  • Each of the elongate reinforcements of the one or more belt plies is characterized as having a rupture force ranging from 420 to 520 N at 23 °C and the elastomeric material of the one or more belt plies is characterized as having a modulus of elongation of less than 10.5 and loss due to hysteresis (P60) at 60 degrees of less than 26.5.
  • the tread includes a plurality of tread features extending a depth within the tread thickness which includes lateral sipes, lateral grooves, and longitudinal grooves, the longitudinal grooves arranged to form a plurality of ribs, each rib extending annularly around the tread and where adjacent ribs are separated by one of the longitudinal grooves, the plurality of ribs including a pair of shoulder ribs and a plurality of central ribs, each of the shoulder ribs arranged along one of opposing widthwise extents of the outer, ground-engaging side and within one of the shoulders and where the plurality of central ribs are arranged between the pair of shoulder ribs.
  • the plurality of tread features extending into the tread thickness substantially to a depth defining a skid depth of the tread, the skid depth being the thickness of the tread intended to be worn during the intended life of the tire tread.
  • One of the shoulder ribs includes an elongate compliance feature comprising a groove or a sipe, the elongate compliance feature extending primarily in a circumferential direction of the tire and into the tread thickness to a depth equal to or less than 75% of the skid depth of the tread at the location of the elongate compliance feature.
  • the lateral sipes and lateral grooves are arranged to provide an average lateral feature spacing of less than 15 mm. It is appreciated that other variations of the tire may vary by incorporating more or less features as described hereinafter in any combination or by varying the present features as described hereinafter.
  • FIG. 1 is a sectional view of a tire taken along a plane extending in both a radial direction and an axial direction, the plane extending through the rotational axis, in accordance with an exemplary embodiment
  • FIG. 2 is a top view of a portion of the tire tread shown in FIG. 1, in accordance with an exemplary embodiment
  • FIG. 3 is a top view of a portion of a prior art tire tread
  • FIG. 4 is a sectional view of the tire shown in FIG. 1, showing how to measure rolling width
  • FIG. 5A is a top view of a tread block showing how to measure average inclination angles of lateral grooves and spacings between lateral features
  • FIG. 5B is a top view of a tread block also showing how to measure average inclination angles of lateral grooves and spacings between lateral features;
  • FIG. 6 is a top view of the tread shown in FIG. 2 that includes exemplary projected longitudinal lengths for the lateral sipes as used to determine lateral sipe edge density;
  • FIG. 7 is a sectional view of a lateral sipe in FIG. 2;
  • FIG. 8 is a partial sectional view of a tire showing a portion of the tire which includes the shoulder of the tire, in accordance with the exemplary embodiment
  • FIG. 9 is a table comparing the results of rolling resistance and cornering stiffness tests conducted on different tire constructions discussed herein;
  • FIG. 10 is a table comparing the results of rolling resistance and cornering stiffness tests conducted on different tire constructions and showing the benefit of adding a new cap ply to TIRE A in FIG. 9;
  • FIG. 11 is a table comparing the results of rolling resistance and cornering stiffness tests conducted on different tire constructions and showing the benefit of adding a new cap ply to TIRE B in FIG. 9;
  • FIG. 12 is a graph comparing the results of concerning stiffness tests conducted on different tire constructions from FIG. 11.
  • low hysteresis (hysteretic) components in a crown portion of a tire reduces rolling resistance
  • low hysteretic components also reduce the rigidity of the crown portion, resulting in degradation of dry braking and tire handling.
  • the present disclosure provides tires characterized as having improved rolling resistance performance (that is, a reduction in rolling resistance) while maintaining handling and grip performance which has not been achieved previously .
  • “Axial direction” or the letter“A d ” in the figures refers to a direction parallel to the axis of rotation A of the tire or tire carcass, and its components, such as the outer band and inner hub, when rolling along a ground surface.
  • “Lateral direction” or“widthwise direction” or the letter LAT is synonymous with axial direction A -
  • “Radial direction” or the letter“R d ” in the figures refers to a direction that is orthogonal to the axial direction and extends in the same direction as any radius that extends orthogonally from the axial direction. “Radially inward” means in the radial direction R d towards rotational axis A. “Radially inward” means in the radial direction R d away from rotational axis A.
  • the circumferential direction is the direction of the tire along which it rolls or rotates and that is perpendicular to the axis of rotation of the tire.
  • the circumferential direction is also referred to as a longitudinal direction LONG d -
  • A“groove” is any elongate void or channel arranged within the tread having a pair of opposing sidewalls extending depthwise into the tread and that which are spaced apart greater than 1.6 mm or, in other variations, by at least 2.0 mm or otherwise by an average distance as measured between the sidewalls for the entire depth of the groove that is greater than 1.6 mm or by 2.0 mm or more.
  • a groove is designed to have a width, based upon the depth of the groove, to remain open as the tread rolls into, through, and out of a contact patch.
  • A“lateral groove” is a groove that extends in a direction oblique to the longitudinal direction (the circumferential direction).
  • A“longitudinal groove” is a groove that extends substantially in the longitudinal direction.
  • A“circumferential groove” is synonymous with a longitudinal groove, each of which extends annularly around the tire.
  • A“sipe” is any elongate void or incision arranged within the tread having a pair of opposing sidewalls extending depthwise into the tread and that which are spaced apart by less than 2.0 mm or 1.6 mm or less in other variations or otherwise by an average distance as measured between the sidewalls for the entire depth of the groove that is less than 2.0 mm or 1.6 mm or less. Sidewalls of the sipe come into contact from time to time as the tread rolls into and out of the contact patch of the tire as the tire rolls on the ground.
  • lateral sipe it is meant a sipe that extends in a direction that is oblique to the longitudinal direction.
  • A“tread element” is portion of the tread defined by one or more grooves and/or sipes arranged along the outer, ground-engaging side of the tread. Examples of tread elements include tread blocks and ribs.
  • A“rib” is a tread element that runs substantially in the longitudinal direction L d of the tire and that is bounded by a pair of longitudinal grooves or by a longitudinal groove and any of the pair of lateral sides defining a width of the tread.
  • a rib may include any lateral features, which includes any lateral grooves and lateral sipes, as well as any arrangement of tread blocks.
  • A“tread block” is a tread element having a perimeter that is defined by one or more grooves with or without a lateral side of the tread, thereby creating an isolated structure in the tread.
  • a sipe does not define any portion of a tread block perimeter.
  • A“contact patch” is the total area contained within a perimeter defining an area of contact, the area of the contact patch including the area of contact contained within the perimeter and any void arranged within the area of contact.
  • “Elastic material” or“elastomer” as used herein refers to a polymer exhibiting rubber-like elasticity, such as a material comprising rubber, whether natural, synthetic, or a blend of both natural and synthetic rubbers.
  • “Elastomeric” as used herein refers to a material comprising an elastic material or elastomer, such as a material comprising rubber.
  • Modulus of elongation was measured at 10% strain (MA10), at 100% strain (MA100), or at 300% strain (MA300) at a temperature of 23 °C based on ASTM Standard D412 on dumb bell test pieces. The measurements were taken in the second elongation; i.e., after an accommodation cycle. These measurements are secant moduli in MPa, based on the original cross section of the test piece.
  • Hysteresis or hysteretic loss is denoted as P60 and is measured as a percentage rebound at the sixth rebound at 60° C, in accordance with the following equation:
  • P60 is obtained through a P8 test that employs a pendulum that is permitted to repeatedly strike and rebound from a test sample.
  • “Resilient” as used herein means configured to bend and flex elastically without plastic or permanent deformation under intended operating conditions.
  • Cords are said to be inextensible when the said cords under a tensile force equal to 10% of the rupture force, exhibit a strain of at most 0.2%.
  • Cords are said to be elastic when the said cords are under a tensile force equal to the rupture load exhibit a strain of at least 3% with a maximum tangent modulus of less than 150 GPa (gigapascals).
  • the“rupture force” maximum load in N (Newtons)
  • rupture strength in MPa (megapascals)
  • elongation at break total elongation in %) measurements are taken under tensile load in accordance with standard ISO 6892, 1984 at a temperature of 23 °C.
  • “Rolling width,” with reference to FIG. 4, refers to a width W RW of the tread 20 that defines a width of the outer, ground-engaging side 22 of the tread 20.
  • This width W RW is defined in accordance with FIG. 4, whereby a distance W R is measured along the radially outermost belt ply 40 2 to the center of the last elongate reinforcement 44 in said ply 40 2 at each widthwise extent of said outermost belt ply 40 2 . In this instance, 1 ⁇ 2 of W R is shown.
  • “Skid depth” or SD 2 o is defined as the thickness of the tread extending from the outer, ground-engaging side of the tread to the deepest tread feature (that is, any longitudinal or lateral groove or sipe) extending into the tread. Any thickness of the tread extending radially inward from the skid depth is referred to as the undertread thickness. In particular instances, with reference to FIG.
  • the skid depth SD20 extends along a curvilinear path laterally across the tread and between adjacent longitudinal grooves 24, intersecting each longitudinal groove bottom 26 and extending further along an arcuate path into each shoulder rib 32si, 32s 2 at the depth of the deepest lateral groove or sipe, where the skid depth SD20 may or may not be arranged substantially the same distance from the radially outermost cap ply 50 or, if no cap ply is present, the radially outermost belt ply 40 for distance W 8 .
  • the skid depth SD20 defines the useful thickness of the tread intended to be worn during the life of the tire.
  • “Projected longitudinal length” is the length of a longitudinal groove, lateral groove, lateral sipe, or elongate compliance feature projected perpendicular to the direction of rotation, that is, the longitudinal component of the length, which by nature extends entirely in a longitudinal direction of the tire/tread.
  • each projected longitudinal length PL forms the X component (which forms the vector component extending in the longitudinal direction) of the lateral sipe length, the projected longitudinal length extending in the longitudinal direction LONG d , where the lateral sipe length is separated into vectors extending separately in the longitudinal direction LONG d and in the lateral direction LAT d .
  • FIG. 6 shows the projected longitudinal lengths for sipes 30, projected longitudinal lengths for each of the longitudinal grooves 24, lateral grooves 28, and elongate compliance features 34 are determined in the same manner.
  • each projected longitudinal length may be based upon the length of the widthwise centerline of each corresponding groove or sipe, or, instead, upon any edge extending along any side forming the width of each groove or sipe.
  • “Longitudinal non-lateral sipe edge density” is the sum of all projected longitudinal lengths of all longitudinal grooves, lateral grooves, and compliance grooves and sipes as described herein, which extend substantially in the longitudinal direction of the tire, divided by the total surface area of the tread as defined by the rolling width.
  • “Longitudinal lateral sipe edge density” is the sum of all projected longitudinal lengths of the lateral sipes in a tire divided by the total surface area of the tread as defined by the rolling width.
  • Dynamic properties“Tg” and“G*” for the rubber compositions were measured on a Metravib Model VA400 ViscoAnalyzer Test System in accordance with ASTM D5992-96.
  • the response of a sample of vulcanized material (double shear geometry with each of the two 10 mm diameter cylindrical samples being 2 mm thick) was recorded as it was being subjected to an alternating single sinusoidal shearing stress of a constant 0.7 MPa and at a frequency of 10 Hz over a temperature sweep from - 60° C to 100° C. with the temperature increasing at a rate of 1.5° C/min.
  • the dynamic shear modulus G* at 60° C. was captured and the temperature at which the max tan delta occurred was recorded as the glass transition temperature, Tg.
  • each tire is ran at a constant speed of 80 km/h on an appropriate automatic machine (machine of the“flat track” rolling road type marketed by the company MTS), by varying the load denoted“Z”, which is a vertical or radial load under a drift angle of 1 degree, and the drift thrust was measured continuously to identify the drift thrust or cornering stiffness denoted“D” (corrected for the drift thrust at zero drift angle), by using sensors to record the transverse load on the wheel as a function of this load “Z”, this then gives the drift thrust or cornering stiffness.
  • machine machine of the“flat track” rolling road type marketed by the company MTS
  • a pneumatic tire 10 is shown to generally comprise a pair of annular bead areas 12 spaced apart axially (that is, in axial direction A d ) along a rotational axis A of the tire 10, a pair of sidewalls 14 spaced apart axially along the rotational axis A of the tire 10, and a crown portion 16 arranged widthwise between the pair of sidewalls 14 and extending annularly around the tire 10.
  • Each sidewall 14 extends outwardly in a radial direction R d from one bead area 12 of the pair of bead areas 12 relative to the rotational axis A.
  • the crown portion 16 In extending widthwise between the pair of sidewalls 14, it is a width Wi 6 of the crown portion 16 extending between the sidewalls. Rolling width W RW of the tread 20 and outer, ground-engaging side 22 is also shown. Shoulder area is generally designated as 18, and includes shoulder ribs 32si, 32s 2 - [0048] With continued reference to FIG. 1, the crown portion 16 includes a tread 20 arranged annularly around the crown portion 16 and forming an outer, ground-engaging side 22 upon which the tire 10 is intended to roll upon. The tread 20 has a thickness t2o extending in a direction perpendicular to the outer, ground-engaging side 22 and in a direction toward the rotational axis A of the tire.
  • the tread thickness t 2 o extends from the outer, ground-engaging side 22 to a skid depth SD 2 o of the tread to define a thickness of the tread intended to be worn during the lifetime of the tire (that is, a wearing depth or thickness of the tire tread).
  • the skid depth SD 2 O is commonly, but not necessarily, arranged at a depth corresponding to the bottom 26 of the deepest longitudinal groove 24. While not necessary, it is commonly the case, such as is shown, where the bottom 26 of all circumferential (longitudinal) grooves 24 is arranged at the skid depth SD 2 o.
  • each circumferential (longitudinal) groove depth D 24 may or may not be of the same depth D 24
  • all circumferential grooves 24 are of equal depth D 24 and extend to and terminate at the skid depth SD 2 O.
  • the average depth D 24 for all circumferential grooves 24 is 8.5 mm. This average is calculated over the full circumference of the tire 10.
  • the skid depth SD 2 o is measured at a widthwise (axial) centerline CLA of the tread 10, the centerline CLA extending along an equatorial plane PCL, where at this location the skid depth SD 2 o is 8.5 mm, but may remain the same or vary across the width of the tread.
  • the skid depth SD 20 remains generally constant until reaching each shoulder 18, while in FIG. 8 the skid depth SD 2 o gradually decreases as the tread extends laterally along its width.
  • tread thickness t 2 o may extend radially inward deeper to the tread beyond the skid depth SD 2 o, such as is generally shown in FIG. 1.
  • Tread 20 is a wearing layer configured and intended to engage a ground surface by way of the outer, ground- engaging side 22 throughout the intended worn life of the tread 20, and may be formed of a single elastomeric material formulation or may comprise a plurality of sub layers formed of different elastomeric material formulations.
  • an inner layer 21 is arranged below tread 20, where tread 20 extends to the skid depth SD 2 o and optionally beyond radially inward.
  • Inner layer 21 is arranged radially inward (in direction R d ) of the skid depth SD 2 o (starting at or below skid depth SD 2 o) and is configured and intended to be a non-wearing layer of the tire, such that it is not intended to form a portion of the outer, ground-engaging side 22 during the intended worn life of the tread 20.
  • Inner layer 21 is arranged radially outward (in direction R ) from belt plies 40 and cap ply 50.
  • Inner layer 21 does not include any elongate reinforcements. In particular embodiments, inner layer 21 may form 15% to 35% of the total volume of elastomeric material forming tread 20.
  • inner layer 21 may have a thickness t 2i as thin as 1 to 2 mm, and which may be greater as desired up to SD 2 o ⁇
  • the inner layer thickness t 2l may extend up to 4 mm or otherwise to maximize the volume between the skid depth SD 2O and the radially outermost reinforced ply, such as any cap ply 50 or belt ply 40, to achieve the desired improvements in rolling resistance. Accordingly, other inner layer thicknesses may be employed in other variations.
  • Inner layer 21 does not form any gum layer or adhesive that may be used to attach a tread to a tire, but rather forms a sub layer to tread 20 having a volume as desired to achieve the material properties desirous to form a tire that achieves the intended tire performance parameters (rolling resistance performance). It is appreciated that inner layer 21 may be formed separate from tread 20 or may be formed therewith, such as when coextruding both tread 20 and inner layer 21 together.
  • inner layer 21 is to provide elastomeric material characterized as having a hysteresis (P60) lower than the elastomeric material forming tread 20, which assists in reducing rolling resistance and controlling tire operating temperatures (so that the tires run cooler).
  • the inner layer 21 is characterized as having a dynamic shear modulus (G*) ranging from 58% to 68% of the dynamic shear modulus (G*) of the tread 20, a modulus of elongation (MA10) ranging from 40% to 60% or substantially 50% of the modulus of elongation (MA10) of the tread 20, and for a maximum tan delta from 60% to 75% of the maximum tan delta of the tread 20.
  • tire treads are commonly formed of elastomeric material formulated for elevated traction (grip) performance. Such traction formulations, however, increase rolling resistance and thereby reduce rolling resistance performance.
  • traction formulations increase rolling resistance and thereby reduce rolling resistance performance.
  • the tread herein includes an inner layer 21 having improved hysteretic properties (lower) relative to the elastomeric material(s) forming the skid depth SD 2O of the tread 20.
  • the inner layer 21 provides improved rolling resistance performance while maintaining traction benefits associated with tread 20.
  • the tread 20 is formed of an elastomeric material, such as any natural or synthetic rubber, or any blend thereof.
  • the tread is substantially formed of an elastomeric material to provide elevated traction (grip) and which is characterized as having a glass transition temperature (Tg) of -25 °C to -10 °C, a maximum tan delta of 0.4 to 0.6, a dynamic shear modulus (G*) of 1.0 to 1.4 MPa, a Mooney viscosity of 80 to 120, and a modulus of elongation (MA10) of 5.75 to 9.5.
  • Tg glass transition temperature
  • G* dynamic shear modulus
  • MA10 modulus of elongation
  • the so characterized elastomeric material is a mixture including an elastomer, a filler, and a plasticizer.
  • the elastomer ranges from an SBR/BR blend containing at least 70% SBR to 100% SBR, or in other variations a 70/30 or 85/15 blend of SBR and BR, respectively.
  • SBR means styrene-butadiene rubber while “BR” means butadiene rubber.
  • SBR is a functionalized elastomer.
  • the filler in this formation comprises silica and carbon black, silica forming 23.5% to 25.9% and the carbon black forming 1 % of the total elastomeric material mixture.
  • the plasticizer in this formation forms 25% to 30% of the total elastomeric material mixture and comprising high Tg resin that forms 12% to 23% of the total elastomeric material mixture and highly oleic sunflower oil that forms the balance of the plasticizer (2% to 18%). It is appreciated that other formations may be employed to achieve the desired characteristics and properties.
  • the elastomers useful for forming the elastomeric material compositions disclosed herein, such as for the tread 20, may have any microstructure, such microstructure being a function of the polymerization conditions used, in particular of the presence or absence of a modifying and/or randomizing agent and the quantities of modifying and/or randomizing agent used.
  • the elastomers may, for example, be block, random, sequential or micro- sequential elastomers, and may be prepared in dispersion or in solution; they may be coupled and/or starred or alternatively functionalized with a coupling and/or starring or functionalizing agent.
  • Exemplary functionalizing agents that could be included with the diene elastomers include, but are not limited to, metal halides, metalloid halides, alkoxy silanes, imine-containing compounds, esters, ester-carboxylate metal complexes, alkyl ester carboxylate metal complexes, aldehydes or ketones, amides, isocyanates, isothiocyanates and imines - all of these being well-known in the art.
  • Particular embodiments may include functionalized diene elastomers while other embodiments may be limited to including no functionalized elastomers.
  • Particular embodiments include at least 80 phr of a functionalized elastomer or alternatively at least 90 phr or 100 phr of a functionalized elastomer wherein the functional moiety interacts with the silica filler.
  • Examples known in the art include silanol functional groups or polysiloxane functional groups having a silanol end (such as described, for example, in FR 2 740 778 or U.S. Pat. No. 6,013,718), alkoxysilane groups (such as described, for example, in FR 2 765 882 or U.S. Pat. No. 5,977,238), carboxyl groups (such as described, for example, in WO 01/92402 or U.S.
  • Particular embodiments of the rubber compositions disclosed herein are limited to those having at least 80 phr of the rubber components being highly unsaturated diene elastomers. Other embodiments are limited to having at least 90 phr or 100 phr of the highly unsaturated diene elastomer components.
  • Suitable highly unsaturated diene elastomers include, but are not necessarily limited to natural rubber (NR) and synthetic rubbers such as polybutadienes (BR), polyisoprenes (IR), butadiene copolymers, isoprene copolymers and mixtures of these elastomers.
  • Such copolymers include butadiene/styrene copolymers (SBR), isoprene/butadiene copolymers (BIR), isoprene/styrene copolymers (SIR) and isoprene/butadiene/styrene terpolymers (SBIR). Any of these examples or mixtures of these examples are suitable for particular embodiments of the rubber compositions disclosed herein.
  • useful SBR elastomers may have a bound styrene content of between 1 mol% and 45 mol% or alternatively between 15 mol% and 40 mol% or between 20 mol% and 30 mol%.
  • Particular embodiments of the rubber compositions disclosed herein include an SBR that is functionalized with a moiety that interacts with the silica filler.
  • the crown portion 16 further includes one or more belt plies 40 (generally, but more specifically as first and second belt plies 40i, 40 2 ) each forming a layer of elastomeric material 42 reinforced with a plurality of elongate reinforcements 44 spaced apart in an array, the one or more belt plies being arranged radially inward and below the tread.
  • the one or more belt plies form a“belt,” the belt also being referred to as a“belt structure” and forming an annular structure formed by all of the one or more belt plies 40).
  • Each elongate reinforcement 44 may be formed of metal or non- metal elongate reinforcements, where the elongate reinforcements 44 are formed of a plurality of filaments arranged lengthwise and twisted along their lengths as desired.
  • Metal elongate reinforcements are constructed from filaments most commonly formed of steel, but may be formed any metal having desirous properties.
  • Non-metal reinforcements are constructed from filaments formed of any fabric or textile, such as polyester, rayon, nylon, aramid, silk, and/or fiberglass.
  • the tire 10 includes a pair of belt plies 40 to form an annular belt structure, although any single belt ply 40 or three or more belt plies 40 may be employed to achieve the desired properties of the annular belt structure formed by any one or more belt plies 40.
  • each belt layer 40 is reduced in comparison to those used previously in prior art passenger tires, which thereby reduces the rolling resistance to generating an overall improvement in rolling resistance performance for tire 10.
  • a lower hysteretic elastomeric material 44 may be employed, which also assists in reducing rolling resistance.
  • Each of these may also reduce the operating temperature of the tire.
  • each of the elongate reinforcements 44 form a 0.60 mm thick steel cable. The cable is formed of two (2) twisted 0.3 mm diameter steel filaments. Each such elongate reinforcement 44 is characterized as having a 470 N rupture force, where in other variations when using other elongate reinforcements may range from 420 to 520 N.
  • the elongate reinforcements 44 are arranged to extend lengthwise greater than 24 degrees and up to 32 degrees relative to the longitudinal direction LONG d , and in other instances 26 degrees to 30 degrees, or substantially 28 degrees relative to the longitudinal direction LONG d -
  • belt plies used for prior high performance passenger tires employed elongate reinforcements forming a steel cable formed of four (4) twisted 0.3 mm diameter steel filaments, each of which were arranged to extend lengthwise 24 degrees relative to the longitudinal direction.
  • the plurality of elongate reinforcements 44 in each of the one or more belt plies 40 are spaced apart centerline-to-centerline by substantially 1 mm with the elastomeric material 42 of each of the one or more belt plies, which defines the pace of the elongate reinforcements 44.
  • the elastomeric material 42 has a thickness of 1.08 mm, and is characterized as having a modulus of elongation of less than 10.5 and loss due to hysteresis (P60) at 60 degrees of less than 26.5 as measured as a result of conducting a P8 pendulum test.
  • each belt ply 40 before application to the tire in an uncured state has a thickness of 1.22 mm (where belt ply used for prior high performance passenger tire was 1.42 mm thick).
  • the mass of each belt ply 40 is reduced 5.5% (reduced from 2.531 kg/mm 2 to 2.394 kg/mm 2 ) relative to belt plies previously used in related passenger (high performance) tires.
  • a reduced hysteretic elastomeric material 42 may be employed, which in certain exemplary instances is characterized as having a hysteresis (P60) of less than 26.5, 23.5 or less, 17.5 to 23.5, or of substantially 20.5.
  • elastomeric material 42 is characterized as having a hysteresis (P60) of substantially 20.5 and a modulus of elongation (MA10) substantially 6 MPa, which is contrasted with elastomeric material used in belt plies of prior high performance passenger tires was characterized as having a hysteresis (P60) of substantially 26.5 and a modulus of elongation (MA10) substantially 10.5 MPa.
  • the crown portion 16 further includes a cap ply 50 arranged radially outward from the one or more belt plies 40 and from the annular belt structure formed by all belt plies contained within the tire.
  • the cap ply 50 is arranged between the tread 20 and the one or more belt plies 40 (that is, the belt).
  • the cap ply 50 extends at least partially or substantially across a full width of at least one of the belt plies 40 or more generally at least partially or substantially across a full width of the belt.
  • the cap ply 50 is at least partially arranged within each shoulder 18 or shoulder rib 32si, 32s 2 -
  • the cap ply 50 is provided to recover rigidity otherwise reduced by the tread design (arrangement of tread features), the inclusion of inner layer 21, and by the change in belt plies 40 as described herein.
  • the provision of the cap layer 50 described herein may be provided as a substitute to other cap layers previously employed by other tires or added to tires not previously incorporating a cap layer.
  • the cap ply 50 is formed of a layer of elastomeric material 52 reinforced with a plurality of elongate reinforcements 54 spaced apart in an array.
  • the elongate reinforcements 54 are arranged to extend lengthwise substantially in a circumferential direction C d of the tire, that is, in a direction substantially parallel to a plane P CL bisecting the tire at its equatorial centerline CL A and extending perpendicular to rotational axis A. “Substantially parallel” means that any such elongate reinforcement 54 extends by an angle or 0 to 5 degrees in absolute value (that is, spanning -5 degrees to 5 degrees) relative to the longitudinal direction LONG d or plane P CL ⁇
  • Cap ply 50 may be applied in any desired manner.
  • cap ply 50 is formed using one or more sheets wound once around the tire, the sheets including the elastomeric material 52 and elongate reinforcements 54, while in other exemplary instances the cap ply 50 is formed using one or more strips wound multiple revolutions around the tire in a helical configuration, the strips including the elastomeric material 52 and elongate reinforcements 54.
  • each wind of the strip is arranged to abut the adjacent wind of strip, or, in other variations, may be spaced apart from or overlap an adjacent wind by as much as a 50% (providing a spacing or overlap, where, for example, a 50% overlap forms 1 ⁇ 2 pace between winds of the strip).
  • one or more cap plies 50 may be employed. At each widthwise end of the belt, before beginning the helical wind at one end and after reaching the other end after making the plurality of helical winds, a full revolution of the cap strip is made. In doing so, the cap ply extends 4 mm to 14 mm beyond the belt, that is, beyond the widest of the one or more belt plies 40 at each widthwise extent of the belt.
  • Each elongate reinforcement 54 may be formed of metal or non-metal elongate reinforcements, where elongate reinforcements are formed of a plurality of filaments arranged lengthwise and twisted along their lengths as desired.
  • Metal elongate reinforcements are constructed from filaments most commonly formed of steel, but may be formed any metal having desirous properties.
  • Non-metal reinforcements are constructed from filaments formed of any fabric or textile, such as polyester, rayon, nylon, aramid, silk, and/or fiberglass.
  • the cap ply is characterized as having a rupture force greater than 3150 N per 15 mm of cap ply width, while in other instances the cap ply is characterized as having a rupture force ranging from 4650 N to 6150 N per 15 mm of cap ply width or substantially 5400 N per 15 mm of cap ply width.
  • the cap ply may also be characterized as having a 4% elongation per 15 mm of cap ply width with application of a 100 N tensile force, and as having a 5.5% elongation per 15 mm of cap ply width with application of a 200 N tensile force.
  • cap ply 50 is formed using a strip, such as a 15 mm wide strip, wound in a helical configuration fully across and beyond a full width of each of the pair of belt plies 40, where each wind of the strip abuts an adjacent wind of the strip and extends by a distance D50 of less than 15 mm beyond the full width of the widest belt ply 40 or of the annular belt structure at each widthwise extent in certain exemplary instances.
  • a strip such as a 15 mm wide strip
  • An exemplary elongate reinforcement 54 that may be employed within any such contemplated cap ply 50, including any cap sheet or cap strip used to form such ply, is characterized as having a rupture force ranging from 310 N to 410 N.
  • each elongate reinforcement 54 is characterized as having a rupture force substantially equal to 360 N, where such elongate reinforcements 54 arranged in an array having a 1 mm pace, where pace is the centerline-to-centerline spacing between adjacent elongate reinforcements 54.
  • the rupture force of the 15 mm wide strip is 5400 N and is characterized as having an elongation of 4% as measured at 100 N force and as having an elongation of 5.5% as measured at 200 N force. While other elastomeric material may be employed, in certain instances elastomeric material used to form any cap ply 50 or cap strip contemplated above may be characterized as follows in Table 1:
  • each elongate reinforcement 54 is formed of a two (2) yam twist, where an aramid 167 filament is twisted with a nylon 140 filament at a rate of 290 turns per meter. In such instances, the rupture force for each elongate reinforcement is 360 N.
  • the array of elongate reinforcements may be coated with the elastomeric material or skim (layers) of elastomeric may be applied to opposing sides of the array. It is appreciated, however, that any other manner may be employed for providing any such ply.
  • a full-width cap layer is applied to a pair of belt plies, the cap layer being formed of elongate reinforcements that are formed of nylon.
  • These prior art elongate reinforcements are characterized as having a 210 N rupture force, and when arranged in a 15 mm wide cap ply strip having a pace of 1 mm, the strip has a rupture force of 3150 N.
  • the cap ply is applied in a Z-configuration, where a cap ply strip is initially applied inward from an intended widthwise extent of the cap ply, the strip being wound outwardly to the nearest widthwise side, such as by two helical winds, for example, and then is wound helically in an abutting arrangement in a lateral direction across the tire to form a full width of the cap ply, and thereafter winding the strip back in towards away from the widthwise extent, such as by two helical winds, to complete the Z-configuration.
  • the prior art cap layer is less rigid in both circumferential and in the axial directions.
  • cap layer 50 overcomes the loss in rigidity provided by the more flexible and compliant tread 20 as achieved by the particular arrangement tread features. Specifically, the cap layer 50 described herein provides an increase in rigidity in the lateral (Y) direction, for improved D(Z) gain (in cornering stiffness) and for improved handling. The cap layer 50 described herein also provides an increase in rigidity in the longitudinal (X) direction, for improved wear and dry braking performance.
  • the pair of prior art belt plies each employ elongate reinforcements each having a rupture force of 875 N and are arranged to extend lengthwise by 24 degrees relative to the longitudinal direction of the tire, where the prior art elongate reinforcements are steel cables formed of four (4) 0.30 mm diameter steel filaments twisted.
  • the tire tread 20 includes a plurality of features extending a depth within the tread thickness that include longitudinal (circumferential) grooves 24, lateral grooves 28, and lateral sipes 30. These features are arranged along the outer, ground-engaging side 22, although any such feature may be submerged below the outer, ground-engaging side 22 to be later exposed after a particular depth of the tread 20 has been worn away.
  • the longitudinal grooves 24 are arranged to form a plurality of ribs 32, each rib extending annularly around the tread such that adjacent ribs are separated by one of the longitudinal grooves 24.
  • the plurality of ribs include a first shoulder rib 32si, a second shoulder rib 32s 2 , and a plurality of central ribs 32c-
  • Each of the first and second shoulder ribs 32si, 32s 2 are arranged along one of opposing widthwise extents of the outer, ground-engaging side 22, where the plurality of central ribs 32c are arranged axially (laterally) between the first and second shoulder ribs 32 ⁇ i , 32 ⁇ 2 ⁇
  • each of the ribs 32 Si , 32 S2 , 32 C may be characterized as having any desired width, where the rib widths W 32 may be the same or different between the ribs 32si, 32s 2 , 32c-
  • each of the first and second shoulder ribs have a width W32 equal to 24% to 29% of the tread width.
  • the width W32 of each first and second shoulder rib 32si, 32s 2 has a width W32 equal to 150% to 170% of an average width of the central ribs 32c, 32s 2 ⁇ While the average width W32 of each central rib 32c may be different than any one or more of the other central ribs 32c, in particular instances the average width W32 of each central rib is substantially the same. It is appreciated that while any number of ribs may be employed, in certain embodiments the tread has 5 ribs (shown) or 6 ribs (not shown). In the embodiment shown, the tire tread features form an asymmetrical, non-directional tire tread pattern design, where non-directional means that the tire may be mounted in to rotate in either of opposing circumferential directions. It is appreciated, however, that a directional tread pattern design may also be employed.
  • longitudinal grooves 24 each has a width W24 defined by a pair of opposing groove sidewalls 27. It is appreciated that each of the longitudinal grooves 24 may have the same of different widths W24, and in particular embodiments the longitudinal groove widths W 24 are selected to provide the longitudinal contact surface ratios discussed elsewhere herein. While each groove sidewall 27 may extend into the tread thickness t 2 o at any angle a relative to a direction perpendicular to the outer, ground-engaging side 22, in particular exemplary instances each groove sidewall 27 extends at an angle a measuring 2° to 12° relative to a direction perpendicular to the outer, ground- engaging side 22. As noted previously, each longitudinal groove 24 has a depth D24 extending into the tread thickness to a bottom 26, where all of the longitudinal grooves may be of the same or different depth D 24 .
  • tread 20 includes lateral grooves 28 and lateral sipes 30, all of which together are referred to as lateral features. It is noted that should any adjacent lateral features be arranged within 1 mm of one another, the adjacent features are considered a single feature. For example, with reference to“0” lateral sipe 30o , in the embodiment shown it is optionally formed from two separate arcs that are arranged within 1 mm of one another, so it is considered a single lateral feature. Likewise, the arrangement of lateral sipe 30 A and of lateral sipe 30 B is considered to form a single lateral features, as each are arranged adjacent to one another within 1 mm.
  • lateral sipe 30o provides a double projected lateral length as defined herein. While the depths of the lateral grooves 28 and lateral sipes 30 may vary, in particular embodiments, the lateral grooves 28 and lateral sipes 30 extend substantially the full skid depth SD 2 o of the tread 20.
  • each lateral feature may include a chamfer 60 arranged at the intersection of a lateral feature 28, 30 (a sidewall thereof) with the outer, ground-engaging side 22.
  • a lateral sipe 30 is shown to include a pair of opposing sipe sidewalls 31, each sipe sidewall 31 extending in the direction of the sipe length and the pair of sidewalls 31 defining a width of the sipe 30, which may be zero (0) when the lateral sipe 30 is a laceration.
  • a chamfer 60 is arranged to form an intersection between the lateral sipe sidewall 31 and the outer, ground-engaging side 22.
  • the chamfer 60 may be any size, in particular embodiments, the chamfer is a 1.5 mm by 1.5 mm chamfer, which extends a depth D 6 o of 1.5 mm into the tread thickness t 2 o and a distance W 6 o of 1.5 mm in a direction normal to the sipe sidewall or to the length of the sipe 30.
  • Arranging chamfers 60 on these lateral features provide additional tread compliance in the lateral direction. In the prior art tread shown in FIG. 3, no lateral sipes are chamfered - only lateral grooves 128 are chamfered.
  • lateral sipes 30 are also chamfered to increase the density of chamfered lateral features to improve lateral compliance for improved snow performance.
  • any one or both sidewalls of the lateral feature may be chamfered along any partial or full length of the lateral feature.
  • a majority of the lateral grooves 28 and at least 50% of the lateral sipes 30 along the outer, ground-engaging 22 side within the rolling width WRW include a chamfer 60 extending along at least a portion of the corresponding groove or sipe length.
  • substantially all (substantially 100%) of the lateral grooves 28 and substantially all (substantially 100%) of the lateral sipes 30 include a chamfer 60 extending along at least a portion of the corresponding groove or sipe length. While each of these different variations may be employed in any embodiment contemplated herein in which any combination of features are included, it is particularly noted that these different variations may be combined with the various sipe densities and edge densities.
  • an average inclination angle is contemplated for the lateral grooves.
  • the average inclination angle y (see FIGS. 5A and 5B) for each of the lateral grooves 28 in each of the shoulder ribs 32si, 32s 2 is greater than 6 degrees and in certain exemplary embodiments may range from 8 to 14 degrees or from 10 to 12 degrees.
  • the average inclination angle y (see FIGS. 5A and 5B) for each of the lateral grooves 28 in the central ribs 32c is greater than 20 degrees while in certain exemplary embodiments may range from 30 to 45 degrees or from 33.5 to 42 degrees.
  • the average inclination angle y for shoulder ribs 32si, 32s 2 is 12 degrees while the average inclination angle y for central ribs 32c is 37 degrees. It is appreciated that within any such range, the average angle may be the same or vary amongst the shoulder ribs 32si, 32s 2 and amongst the central ribs 32c-
  • angles y may be measured relative to the longitudinal direction LONG d , where angle y is measured between the longitudinal direction LONG d and a line L ⁇ extending normal to the groove length L28.
  • each lateral groove 28 extends linearly.
  • the average angle may be measured differently.
  • the average angle y is obtained by extending an imaginary line L avg from the terminal ends of the lateral groove length L28 at a widthwise centerline CLw of the lateral groove 28, where the terminal ends here are arranged at each lateral side of the tread block although in other variations a lateral groove may terminate inward of any side edge of the tread block.
  • an imaginary line L avg may be determined using linear regression taking into account the lengthwise path of the longitudinal groove widthwise centerline CLw- Once the imaginary line L avg is determined, angle y is measured relative to a line L ⁇ extending normal therefrom. In other variations, angle y may be measured relative to the lateral direction LAT d from a linear longitudinal groove length L28 or from the imaginary line L avg .
  • an average spacing is contemplated for all lateral features, that is, all lateral grooves 28 and all lateral sipes 30.
  • a spacing S (Si, S 2 , S3, S4) is provided between adjacent lateral features 28, 30, whether adjacent lateral features form a pair of lateral grooves 28, a pair of lateral sipes 30, or a lateral groove 28 and a lateral sipe 30.
  • LS identifies a leading side of the tread block shown as formed by a lateral groove
  • TS identifies a trailing side of the tread block as formed by a lateral groove.
  • the spacings S are shown to be constant, spacings S may be variable in other instances.
  • the average lateral feature spacing for each of the lateral features 28, 30 in each of the shoulder ribs 32si, 32s 2 is less than 15 mm, while in certain instances the average lateral feature spacing may range from 12 mm to 14.5 mm, while in more specific instances the average lateral feature spacing is substantially 13.7. It is appreciated that within any such range, the average angle may be the same or vary amongst the various ribs 32si, 32s 2 , and 32c-
  • spacings S are measured relative to the longitudinal direction LONG d , where spacing S is measured in the direction of a line L ⁇ extending normal to the lateral feature length L28 , L 3 o.
  • each lateral feature 28, 30 extends linearly.
  • the spacing S (Si, S2, S 3 ) is measured in a direction defined by a line L ⁇ extending normal to an imaginary line L avg extending through the terminal ends of the lateral groove length L28 at a width wise centerline CLw of the lateral groove 28, where the terminal ends here are arranged at each lateral side of the tread block although in other variations a lateral groove may terminate inward of any side edge of the tread block.
  • an imaginary line L avg may be determined using linear regression taking into account the lengthwise path of the longitudinal groove widthwise centerline CLw- Once the imaginary line L avg is determined, the spacings S (Si, S2, S3) are measured in the direction of line L ⁇ extending normal to line L avg . By virtue of providing shorter spacings (increased density), improvements in rolling resistance are observed due to the reduction in flattening forces within the crown portion.
  • each of the tread features that is, each of the longitudinal grooves 24, lateral grooves 28, lateral sipes 30, and elongate compliance features 34 (partial depth grooves or sipes extending substantially in the longitudinal direction LONG d ) form edges located at the intersection of the depthwise extension of each such tread feature and the outer, ground-engaging side 22.
  • an edge is formed where any sidewall of any lateral sipe or of any lateral groove intersects the outer, ground-engaging side.
  • some of these tread features may include one or more chamfers 60, and so the edges may be arranged at the intersection of the chamfer with the outer, ground-engaging side 22.
  • a longitudinal lateral sipe edge density may be determined for the lateral sipes 30, while a longitudinal non-lateral sipe edge density may be determined collectively for the other tread features, namely, for all longitudinal grooves 24, lateral grooves 28, and the elongate compliance features 34 (that is, all partial depth grooves or sipes extending in the longitudinal direction), in combination.
  • the longitudinal non-lateral sipe edge density is greater than the prior art tire 110 shown in FIG. 3, that is, greater than 21.1 micrometers/mm 2 , while in more specific instances this longitudinal edge density ranges from 28 to 45 micrometers/mm 2 or is 37.9 micrometers/mm 2 .
  • the longitudinal lateral sipe edge density is greater than the prior art tire 110 shown in FIG. 3, that is, greater than 5.5 micrometers/mm 2 , while in more specific instances longitudinal edge density ranges from 7 to 11 micrometers/mm 2 or is 9.5 micrometers/mm 2 .
  • an elongate compliance feature 34 may be provided by arranging an elongate compliance feature 34 along any one or both of the shoulder ribs 32si, 32s 2 .
  • an elongate compliance feature 34 is arranged along inner shoulder rib 32si.
  • An elongate compliance feature 34 extends lengthwise substantially in a longitudinal direction LONG d of the tire 10 and into the tread thickness t 2 o to a depth D 34 equal to or less than 75% or 25% to 75% of the skid depth SD 2 o at the location of the elongate compliance feature or of any longitudinal groove depth D 24 .
  • elongate compliance feature 34 does not extend as deep as any longitudinal groove 24 (that is, depth D 24 is always greater than depth D 34 ). It is appreciated that the elongate compliance feature depth D 34 may remain constant or vary along its length. In the embodiment shown, the elongate compliance groove depth D 34 remains constant.
  • elongate compliance feature 34 In extending substantially in the longitudinal direction LONG d , elongate compliance feature 34 extends lengthwise along its length at an average angle of 15 to -15 degrees relative to the longitudinal direction LONG d - Accordingly, in these variations, elongate compliance feature 34 may extend lengthwise along a linear path in the longitudinal direction LONG d (that is, along a path extending annularly around the tread within a plane arranged parallel to plane PCL), ) or lengthwise along a non-linear path (that is, along a path that extending annularly around the tread only partially within a plane arranged parallel to plane PCL)) and therefore may extend annularly around the tread 20 or may extend discontinuously from tread block to tread block, such as when the elongate compliance feature 34 extends lengthwise at an angle biased to the longitudinal direction LONG,i In the embodiment shown, elongate compliance feature 34 extends linearly along an annular path in the circumferential direction C d around the tread 20.
  • Elongate compliance feature 34 also has a width W34 extending between opposing sidewalls 35. While the width may be any desired width, in the embodiment shown, the groove width W34 is 1 to 3 mm wide. Therefore, elongate compliance feature 34 may form a sipe or a groove. By virtue of including substantially longitudinal compliance features in shoulder ribs or elsewhere, improvements in rolling resistance are observed due to the reduction in flattening forces within the crown portion.
  • longitudinal contact surface ratio (longitudinal CSR) associates the total area of the outer, ground-engaging side minus all void present along the outer, ground- engaging side provided by all circumferential grooves with the total area arranged along the outer, ground-engaging side 22 in the form of a ratio.
  • the total area of the outer, ground- engaging side 22 includes both the surface area of the tread and all void arranged along the outer, ground-engaging side, represented as surface area void along the outer, ground- engaging side.
  • the tread may be characterized as having a longitudinal contact surface ratio of 0.75 to 0.80.
  • the total volumetric void contained in the tread in an unworn state is 0.3 to 0.33.
  • the prior art tread 120 is characterized as having a sipe density of 15.1, which is less than the sipe density described for the treads described herein. Also, the prior art tread 120 is characterized as having lateral features that are arranged at a lower average angle relative to the longitudinal direction LONG d , which more specifically provides an average lateral feature angle of 6 degrees in the shoulder ribs and an average lateral feature angle of 20 degrees in the central ribs. While both the prior art and the new tread designs include chamfers on lateral grooves all lateral grooves, no lateral sipes in the prior art tread design include chamfers. Additionally, no elongate compliance feature is included in the prior art tread design.
  • an increase in edges in both the circumferential direction and axial direction provide improved snow traction while also reducing the rigidity in the axial direction for improved snow handling.
  • reduction in axial rigidity can penalize wet/dry handling.
  • the increase in sipe density (providing more closely spaced sipes) can reduce dry braking performance.
  • tread material according to the formulations discussed above for improving traction performance can reduce the rigidity of the tread, thereby penalizing wear and handling performance.
  • tread material formulations and crown constructions such as by using particular cap layer constructions to recover rigidities reduced in each of the longitudinal and lateral directions, in addition to improvements in snow performance, dry performance is maintained and not reduced while wear performance is improved.
  • FIGS. 10 and 11 it is shown how the substitution of full width cap ply 50 for the prior art cap layer in each of the tire constructions tested (TIRE A and TIRE B) in FIG. 9 transforms the reduction in cornering stiffness to a resulting improvement in cornering stiffness relative to the reference tire REF.
  • Tire constructions TIRE A* and TIRE B* are modified versions of TIRE A and TIRE B, respectively, where the new full width cap ply 50 has been substituted for the prior art cap.
  • FIG. 12 the results of cornering stiffness tests shown in FIG.
  • TIRE B and TIRE B* are shown more fully relative to REF, showing the benefits of including a full width cap ply 50 as described herein in combination with the tread inner layer 21 and a belt consisting of two reduced mass belt plies 40 as described herein.
  • TIRE B* the full width cap ply 50
  • the remaining combination of new features in an otherwise similarly constructed tire (TIRE B) exhibited a reduction in cornering stiffness relative to a reference tire (REF) reflecting prior art tire constructions described above.
  • REF reference tire
  • the terms “comprising,” “including,” and “having,” or any variation thereof, as used in the claims and/or specification herein, shall be considered as indicating an open group that may include other elements not specified.
  • the terms“a,”“an,” and the singular forms of words shall be taken to include the plural form of the same words, such that the terms mean that one or more of something is provided.
  • the terms“at least one” and“one or more” are used interchangeably.
  • the term“single” shall be used to indicate that one and only one of something is intended. Similarly, other specific integer values, such as “two,” are used when a specific number of things is intended.

Abstract

Des modes de réalisation de l'invention comprennent des pneus ayant des performances de résistance au roulement améliorées. Lesdits pneus comprennent une nappe de sommet s'étendant au moins partiellement sur toute la largeur d'au moins l'une des nappes de ceinture, la nappe de sommet étant caractérisée comme ayant une force de rupture supérieure à 210 N pour 15 mm de la largeur de nappe de sommet. Lesdits pneus comprennent également une couche intérieure de matériau élastomère dépourvue de tout renfort allongé, la couche intérieure étant agencée radialement vers l'intérieur à partir de la bande de roulement entre la bande de roulement et toute nappe de ceinture et le pli de sommet, la couche intérieure étant sensiblement constituée d'un matériau élastomère caractérisé en ce qu'il présente une hystérésis inférieure à une hystérésis du matériau élastomère formant la bande de roulement. Des nappes de ceinture à hystérésis réduite et une rainure ou lamelle de conformité peuvent également être agencées à l'intérieur d'au moins une nervure d'épaulement. La bande de roulement comprend également une densité réduite d'éléments de bande de roulement latéraux.
PCT/US2017/069139 2017-12-30 2017-12-30 Pneu à performance de résistance au roulement améliorée WO2019133009A1 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022087705A1 (fr) 2020-10-30 2022-05-05 Santos Turozi Alexandre Blindage anti-trous pour pneumatiques
CN114867618A (zh) * 2019-12-24 2022-08-05 米其林企业总公司 改善噪声的胎面

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EP1127909A1 (fr) 2000-02-24 2001-08-29 Société de Technologie Michelin Composition de caoutchouc vulcanisable, utilisable pour fabriquer un pneumatique, et pneumatique comprenant cette composition
WO2001092402A1 (fr) 2000-05-26 2001-12-06 Societe De Technologie Michelin Composition de caoutchouc utilisable comme bande de roulement de pneumatique
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CN114867618A (zh) * 2019-12-24 2022-08-05 米其林企业总公司 改善噪声的胎面
WO2022087705A1 (fr) 2020-10-30 2022-05-05 Santos Turozi Alexandre Blindage anti-trous pour pneumatiques

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