WO2017075371A1 - Bandes de roulement de pneumatique ayant des éléments de bande de roulement avec des côtés avant et arrière inclinés sur le plan radial et sollicités sur le plan axial - Google Patents

Bandes de roulement de pneumatique ayant des éléments de bande de roulement avec des côtés avant et arrière inclinés sur le plan radial et sollicités sur le plan axial Download PDF

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Publication number
WO2017075371A1
WO2017075371A1 PCT/US2016/059351 US2016059351W WO2017075371A1 WO 2017075371 A1 WO2017075371 A1 WO 2017075371A1 US 2016059351 W US2016059351 W US 2016059351W WO 2017075371 A1 WO2017075371 A1 WO 2017075371A1
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WO
WIPO (PCT)
Prior art keywords
tread
average
tire
longitudinally
angle
Prior art date
Application number
PCT/US2016/059351
Other languages
English (en)
Inventor
Francois Hottebart
Mark Collett
Original Assignee
Compagnie Generale Des Etablissements Michelin
Michelin Recherche Et Technique S.A.
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Filing date
Publication date
Application filed by Compagnie Generale Des Etablissements Michelin, Michelin Recherche Et Technique S.A. filed Critical Compagnie Generale Des Etablissements Michelin
Publication of WO2017075371A1 publication Critical patent/WO2017075371A1/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
    • B60C11/03—Tread patterns
    • B60C11/0306—Patterns comprising block rows or discontinuous ribs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C19/00—Tyre parts or constructions not otherwise provided for
    • B60C19/001—Tyres requiring an asymmetric or a special mounting
    • 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
    • B60C11/13—Tread patterns characterised by the groove cross-section, e.g. for buttressing or preventing stone-trapping
    • B60C11/1307—Tread patterns characterised by the groove cross-section, e.g. for buttressing or preventing stone-trapping with special features of the groove walls
    • B60C11/1323—Tread patterns characterised by the groove cross-section, e.g. for buttressing or preventing stone-trapping with special features of the groove walls asymmetric
    • 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
    • B60C2011/0372—Lateral grooves, i.e. having an angle of 45 to 90 degees to the equatorial plane with particular inclination angles

Definitions

  • This invention relates generally to tire treads, and tires having the same.
  • Tire treads are known to include a partem of voids and/or discontinuities such arranged along a ground-engaging side of the tread to provide sufficient traction and handling during particular conditions.
  • grooves provide voids into which water, mud, or other environmental materials may be diverted to better allow the tread surface to engage a ground surface.
  • tread elements are formed along the tread, where the outer portion of said elements are arranged along the outer side of the tread to provide traction as the outer side engages the ground surface (that is, a surface upon with the tire operates, which is also referred to herein as a tire operating surface).
  • the tire tread wears during tire operation due to the generation of slip between the outer side of the tread and the tire operating surface. This wear occurs due to rolling mechanics and due to the amount of vertical pressure applied to the tire during tire operation.
  • rolling mechanics the shear strain of the tread rubber is maximum at a trailing edge of a tire contact patch (also referred to as a tire footprint), which is the area of contact between the tire and a ground surface.
  • the trailing edge is the edge of the contact patch where the tire rotates out of contact with the ground surface.
  • This shear strain is needed to generate the longitudinal and/or transversal forces required for vehicle motion.
  • the vertical pressure applied to the tread rubber the pressure is applied normal to the tread rubber in contact with the ground surface within the contact patch.
  • This normal pressure decreases to zero at the trailing edge of the contact patch.
  • the high shear strain present generates high tangential stresses as the strain and stresses are associated by the shear rigidity of the tread. Slip occurs when the ratio between high tangential shear stresses and decreasing normal pressure reaches a threshold limit, which is typically 1 for dry ground conditions (Coulomb's law).
  • Embodiments of the present invention include a tire tread, a tire including the tire tread, and methods of reducing tread wear on a tire.
  • Particular embodiments of the tire tread include: a tread length extending in a lengthwise direction normal to a width of the tire tread; a tread thickness extending in a depthwise direction from an outer, ground-engaging side, the depthwise direction extending normal to both the tread width and the tread length; and, the tread width extending laterally in a direction transverse to the tread thickness and to a length of the tread, the width extending laterally between a first lateral side edge and a second lateral side edge of the tread.
  • Such treads also include a plurality of longitudinal grooves extending in a direction of the tread length and a plurality of tread elements.
  • Each of the one or more tread elements being arranged between a pair of lateral discontinuities extending in a direction of the tread width, where one of the pair of lateral discontinuities is arranged adjacent to a first longitudinally-spaced side of the tread element and where the other of the pair of discontinuities is arranged adjacent to the a second longitudinally-spaced side of the tread element such that the pair of lateral discontinuities and the first and second longitudinally-spaced sides of the tread element are spaced-apart in a direction of the tread length to define a length of the tread element.
  • the first longitudinally-spaced side being a leading side of the tread element and the second longitudinally-spaced side being a trailing side of the tread element, where leading side is configured to enter a tire footprint before the trailing side.
  • first longitudinally-spaced side is oriented at an average radial first-side angle relative to the depthwise direction of the tread and the second longitudinally-spaced side is oriented at an average radial second-side angle relative to the depthwise direction of the tread, where the tread is configured to rotate in a direction of rotation of a tire.
  • the direction of rotation comprising one of opposing directions of the tread length, such that a positive average radial first-side angle orientation and a positive average radial second-side angle orientation is obtained when the respective first longitudinally-spaced side and the second longitudinally-spaced side are each increasingly inclined in the direction of tread rotation as each respective first longitudinally- spaced side and second longitudinally-spaced side extend in a direction of the tread thickness towards the outer, ground-engaging side of the tread.
  • an average radial inclination angle comprising a combined average of the average radial first-side angle and the average radial second-side angle for all of the plurality of tread elements along the first and second longitudinally-spaced sides is substantially greater than zero.
  • the first longitudinally-spaced side is oriented at an average axial first-side angle relative to the widthwise direction of the tread and the second longitudinally-spaced side is oriented at an average axial second-side angle relative to the widthwise direction of the tread.
  • an average axial inclination angle comprising a combined average of the average axial first-side angle and the average axial second-side angle for all of the one or more tread elements along the first and second longitudinally-spaced sides is substantially greater than zero.
  • FIG. 1 is a perspective, partial cutaway view of a tire, in accordance with an embodiment.
  • FIG. 2 is a partial side view of the tire tread shown in FIG. 1.
  • FIG. 3 is a partial side view of a prior art tire tread.
  • FIG. 4 is a partial side view of an alternative embodiment of the tire tread shown in FIG. 2.
  • FIG. 5 is a top view of the tire tread shown in FIG. 1.
  • FIG. 6 is a top view of alternative embodiment of the tire tread shown in FIG. 5 showing submerged discontinuities.
  • FIG. 7 is a side view of a tire arranged along a ground surface, in accordance with an embodiment.
  • FIG. 8 is a chart showing the variation in longitudinal forces generated in a tire footprint for (A) a prior art tire under torque, (B) a tire including the inventive features shown in FIG. 3 under torque, and (C) the tire of (B) in a free rolling condition.
  • FIG. 9 is a top view of a tire footprint in an exemplary arrangement.
  • FIG. 10 is a sectional view of the tire shown in FIG. 1.
  • Various embodiments of the invention described herein provide a tire tread exhibiting improved wear characteristics, such as when the tire tread is exposed to a driving torque or acceleration, for example.
  • Particular embodiments of the invention comprise a tire including any such tire tread.
  • a tire footprint is described as a portion of the tire tread that contacts the tire operating surface (such as the ground, for example) during tire operation.
  • a footprint is also referred to as a "contact area" or “contact patch.”
  • the outer, ground-engaging side 22 of a tire tread rolls into contact with the tire operating surface G at a leading edge LE of a tire footprint FP, where a portion of the tread rolls into and enters the footprint, while the ground-engaging side rolls out of contact with the tire operating surface at a trailing edge TE of the tire footprint, where a portion of the tread rolls out of and exits the footprint.
  • an exemplary footprint is shown.
  • slip between the tread and the tire operating surface occurs, which leads to the generation of tread wear.
  • high shear strains are present, which leads to high tangential stresses - represented by elevated longitudinal forces. This is generally represented in plot (A) in FIG. 8, showing the presence of longitudinal forces along a length of an exemplary tire footprint.
  • tread wear which may comprise excessive rates of wear and/or irregular wear.
  • irregular wear includes heel and toe wear, where the leading edge of the tread element wears to a rounded profile and the trailing edge of the tread element wears to an elongated, pointed profile, whereby the leading edge resembles a heel and the trailing edge a toe.
  • a second test tire characterized as having leading and trailing sides with average radial inclination angles of 0 degrees and average axial inclination angles of 36 degrees in absolute value along intermediate ribs, where the intermediate ribs are generally represented by those shown in the tire tread of FIG. 5, with the average axial inclination angles for each of the five (5) ribs arranged across the tread width being 0 degrees, 36 degrees, -36 degrees, 36 degrees, and 0 degrees; and,
  • a third test tire characterized as having leading and trailing sides with average radial inclination angles of 15 degrees and average axial inclination angles of 36 degrees in absolute value along intermediate ribs as provided in the second test tire, where the tire more specifically represents the tire of FIG. 5.
  • leading and trailing sides of a tread element extend at least partially in a direction of the tread thickness and in a direction of the tread width, where the leading and trailing sides are spaced-apart to form a length of the tread element.
  • the leading side is arranged before the trailing side in a direction of the tire rotation, such that the leading side enters a tire footprint before the trailing side.
  • the leading side is referred to herein as a first longitudinally-spaced side
  • the trailing side is referred to herein as a second longitudinally-spaced side.
  • a tread element refers to a tread block or lug or a tread rib, where the length of the tread element is defined by a pair of opposing discontinuities spaced-apart in a direction of the tread length, where one of the discontinuities is arranged along the first longitudinally-spaced side of the tread element and the other of the pair of discontinuities is arranged along the second longitudinally-spaced side of the tread element.
  • Each discontinuity of the pair of discontinuities may comprise any desired discontinuity, such as a sipe or a groove, for example.
  • the tread element when the tread element forms a rib, the tread element (and therefore the rib) extends substantially the full length of the tread, whereby the tread element length (and therefore the rib length) extends in a direction of the tread length (a longitudinal direction of the tread), such that when the tread is arranged around a tire, the rib is arranged in a circumferential direction of the tire.
  • a plurality of tread elements may be arranged to form a rib.
  • the rib length may extend along a linear path (prior to installation on a tire, such as a retread), a constant radius curvilinear path (where the path extends in one direction around a tire), or an undulating non-linear path, which is a laterally undulating path (that is, where the path alternates back and forth in a direction of the tread width as the path extends in a direction of the tread length).
  • a tread element may have a width that is equal to or less than the width of the tread. When the tread element width is equal to a width of the tread, the width of the tread element is bounded or defined by the opposing lateral sides of the tread width.
  • a discontinuity may comprise a sipe or a groove.
  • a sipe comprises a slit or laceration or a narrow groove generally having a molded void width or thickness of 0.5 to 1.2 mm or less or otherwise configured, such that opposing sides of the sipe defining the sipe width or thickness contact or close during tire operation, such as when the sipe is arranged within a tire footprint.
  • a groove has a width or thickness greater than that of a sipe, and is configured to remain open during tire operation, such as when the groove is arranged within a tire footprint to receive and evacuate water, snow, mud, or other environmental materials through which the tire is traveling.
  • any discontinuity extends into the tread thickness by any desired depth, but generally at least 2 mm in particular embodiments.
  • the discontinuity also has a length extending at least partially in a direction of the tread width, and partially or fully across the width of any tread element. It is appreciated that the length of the discontinuity may extend entirely or partially in the direction of the tread width (that is, in a direction normal to the tread length). When extending partially in the direction of the tread width, the length of the discontinuity extends in both the direction of the tread width and the direction of the tread length, such that the discontinuity length extends along a path having a vector extending in a direction of the tread width and a vector extending in a direction of the tread length.
  • the length of the discontinuity may extend along any desired path, whether a linear or non-linear path.
  • a non-linear path includes curvilinear and undulating paths.
  • An undulating path extends back and forth, in an alternating manner, whether in linear or non-linear paths.
  • any tread discussed herein may be arranged along a tire, or may be formed separately from a tire as a tire component for later installation on a tire carcass, in accordance with any technique or process known to one of ordinary skill in the art.
  • the treads discussed and referenced herein may be molded with a new, original tire, or may be formed as a retread for later installation upon a used tire carcass during retreading operations. Therefore, when referencing the tire tread, a longitudinal direction of the tire tread is synonymous with a circumferential direction of the tire when the tread is installed on a tire.
  • a direction of the tread width is synonymous with an axial direction of the tire or a direction of the tire width when the tread is installed on a tire.
  • a direction of the tread thickness is synonymous with a radial direction of the tire when the tread is installed on a tire. It is understood that the inventive tread may be employed by any known tire, which may comprise a pneumatic or non-pneumatic tire, for example.
  • any of the tread features discussed herein may be formed into a tire tread by any desired method, which may comprise any manual or automated process.
  • the treads may be molded, where any or all discontinuities therein may be molded with the tread or later cut into the tread using any manual or automated process.
  • any one or both of the pair of opposing discontinuities may be originally formed along, and in fluid communication with, the outer, ground-engaging side of the tread, or may be submerged below the outer, ground-engaging side of the tread, to later form a tread element after a thickness of the tread has been worn or otherwise removed during the life of the tire.
  • the longitudinal force is reduced by a fixed value based upon a radial inclination angle selected for the leading and trailing sides of the one or more tread elements, which may, for the tire, result in the reduction or elimination of the longitudinal force at the trailing edge of the tire footprint.
  • the longitudinal force may even be reduced below a zero value, which would then result in a negative longitudinal force, which induces a braking force on the tire. This would occur when a longitudinal force being applied to a tire, or a portion of a tire tread spaced apart from the maximum length of a sufficiently rounded footprint (see discussion below), is less than the reduction in longitudinal force generated by the radial inclination angle. This is represented in plot (C) of FIG.
  • a footprint is the contact area between the tire tread and a tire operating surface, such as a road, ground, or any other surface upon which the tire engages during vehicle operation.
  • the shape or lateral profile of a footprint may be more or less rounded as the footprint extends widthwise from a longitudinal center of the footprint to each of the lateral sides of the footprint, which also extends in a lateral direction of the tire tread.
  • a tire footprint is said to have a length, extending in a direction transverse (that is, perpendicularly) to the lateral direction of the footprint. Commonly, the length of the footprint decreases to its shortest lengths nearest the lateral sides of the footprint.
  • the shape or lateral profile of the footprint is dependent upon many variables, including without limitation, the stiffness of a tire's construction, tire inflation pressure, and the roundness of a lateral profile of the outer, ground-engaging side of the tire tread.
  • the lateral profile of the outer, ground-engaging side the lateral profile may be more or less rounded as the tread extends widthwise from a center of the tread to each of the lateral sides of the tread.
  • the lateral sides of the tread experience a drop in outer diameter (or radius) relative a widthwise centerline of the tread.
  • the longitudinal force generated by the tread decreases in areas of the footprint where the footprint length is reduced, that is, reduced from a maximum length. It is appreciated that any such reduction in longitudinal force may result in a negative longitudinal force, which is a braking force.
  • any leading and trailing side of a tread element should take into consideration the roundness of the footprint, since for rounder footprints, the selection of a particular positive radial inclination angle for a leading and trailing side of the tread element may result in significant braking forces being generated by portions of the tread spaced laterally from a maximum footprint length, which would increase tire wear or generate irregular wear, such as in the form of heel and toe wear, and be counterproductive to the intended result of reducing tread wear.
  • the positive radial inclination angles for each of the leading and trailing sides of a tread element may be limited to tires having less round footprints. It is also noted that because the reduction in longitudinal force is fixed for a particular positive radial inclination of the leading and trailing sides of a tread element, a substantially non-zero axial inclination of the leading and trailing sides of a tread element may be employed to provide additional improvements in wear performance.
  • particular embodiments of the invention comprise methods of reducing tread wear on a tire.
  • One step includes providing a tread, which may comprise any tire tread described or contemplated herein, having one or more tread elements characterized as having an average radial inclination angle substantially greater than zero and an average axial inclination angle substantially non-zero.
  • a tread which may comprise any tire tread described or contemplated herein, having one or more tread elements characterized as having an average radial inclination angle substantially greater than zero and an average axial inclination angle substantially non-zero.
  • an average radial and/or axial inclination angle for any tread element is selected that is lower than an average inclination angle otherwise selected for a tire having a less round footprint.
  • the average radial and/or axial inclination angle is selected which is higher than a corresponding average inclination angle otherwise selected for a tire having a rounder footprint.
  • the average radial and/or axial inclination angle is selected that is lower than a corresponding average inclination angle otherwise selected for a tire operating under a greater driving torque.
  • the average radial and/or axial inclination angle is selected that is higher than a corresponding average inclination angle otherwise selected for a tire operating under a lower driving torque.
  • a lower average inclination angle is selected, or more generally an average inclination angle is selected, for a tire tread having a less round footprint, such as those described below having limited differences in lengths (or associated with tires having limited shoulder drops) to reduce or avoid an increase in heel and toe wear along the tire tread.
  • the average inclination angles as described herein that is, where leading and trailing sides have particular average radial and/or axial inclination angles
  • heel and toe wear is reduced or an increase avoided but-for said angles being employed on tires having rounder footprints.
  • the tire 10 comprises a pneumatic tire having a pair of sidewalls 12 each extending radially outward from a rotational axis A of the tire to a central portion 14 of the tire 10.
  • the central portion 14 of the tire is annular in shape, and includes a tread 20 having a thickness T20 extending in a radial direction of the tire (relative a rotational axis of the tire) from an outer, ground-engaging side 22 of the tread to a bottom side 24 for attachment and bonding to the tire.
  • the tread also has a width W20 extending in a lateral direction ("laterally") between the pair of opposing, lateral sides 21 comprising a first lateral side and a second lateral side of the tread each arranged adjacent to one of the sidewalls 12.
  • the tread also has a length L 2 o extending circumferentially around the tire. It can be said that the width extends laterally in a direction transverse to the tread thickness T20 and to a length L 2 o of the tread, which can be said to extend longitudinally in a circumferential direction of the tire.
  • the tread has a length, a width, and a tread thickness, the thickness extending inward from an outer, ground-engaging side in a direction normal to both the width and length of the tread, which is also referred to as a depthwise direction of the tread.
  • the tread also includes a pair of shoulders 21s forming a transition between the outer, ground- engaging side 22 and each lateral side 21 of the tread 20. While the tread is shown to form a portion of a tire, in other embodiments, the tread may be separate from the tire, such as when the tread is formed prior to being applied to a tire during retreading operations.
  • discontinuities 26 comprise voids 26A V , 26B V forming grooves and sipes 26Bs.
  • discontinuities 26A V comprise longitudinal grooves having a length extending in a direction of the tread length, which is in a circumferential direction C of the tire
  • discontinuities 26B V , 26Bs comprise lateral grooves and lateral sipes, respectively, each having a length extending in a direction of the tread width W 2 o, which is in an axial direction A of the tire.
  • Each discontinuity 26 also has a depth D 2 6 extending into the tread thickness T20 from the outer, ground-engaging side 22, which is also shown to be in a radial direction R of the tire. It is appreciated that, in particular embodiments, such as is shown in different exemplary embodiments in FIGS. 4 and 6, the outer, ground engaging side 22 from which any discontinuity extends may be obtained after a thickness of the tread has been worn to reach or expose a submerged discontinuity 26B V .
  • a submerged discontinuity may comprise any discontinuity contemplated herein, including a groove or a sipe, for example.
  • the discontinuities together with longitudinally-spaced sides define a plurality of tread elements comprising tread blocks or lugs.
  • each of the one or more tread elements 28 are arranged between a pair of discontinuities 26B V extending in a direction of the tread width W20.
  • the pair of discontinuities 26B comprise a pair of lateral grooves 26B V or a lateral groove 26B V and a lateral sipe 26Bs, but may comprise any combination of any discontinuity contemplated herein.
  • one of the pair of discontinuities 26B which is also referred to as a first discontinuity, is arranged adjacent to a first longitudinally-spaced side 32A of the tread element, while the other of the pair of discontinuities 26B, which may be referred to as a second discontinuity, is arranged adjacent to the a second longitudinally-spaced side 32B of the tread element such that the pair of discontinuities and the first and second longitudinally- spaced sides of the tread element are spaced-apart in a direction of the tread length L 2 o to define a length L 2 8 of the tread element.
  • the first longitudinally-spaced side 32A of the tread element is a leading side of the tread element, which enters a footprint before a trailing side of the tread element, which is the second longitudinally-spaced side 32B.
  • the one or more tread elements 28 comprise a plurality of shoulder tread elements 28s and a plurality of intermediate tread elements 28i.
  • the plurality of shoulder tread elements 28s comprise one or more first shoulder tread elements arranged along the first lateral side 21 of the tread and one or more second shoulder tread elements arranged along the second lateral side 21 of the tread.
  • the plurality of intermediate tread elements 28i are arranged between the first and second shoulder tread elements 28s, where a plurality of discontinuities 26A (comprising longitudinal grooves in the embodiment shown) separate the plurality of first and second shoulder tread elements and the intermediate tread elements.
  • the one or more tread elements 28 comprise a plurality of tread elements arranged in a direction of the tread length L 2 o in a spaced-apart arrangement to form one or more ribs 30.
  • the rib extends in a circumferential direction C of the tire.
  • a rib 30 can be described as an array of tread elements 28 arranged in a direction of the tread length. It is appreciated that a rib may comprise any known rib.
  • a rib may extend partially or fully along the length of the tread, and may extend partially or fully in the direction of the tread length, such that, in particular embodiments a rib extends annularly around the tire.
  • a rib may be said to have a length extending in a direction of the tread length, where the rib extends along a linear path, or a constant radius curvilinear path when arranged along tire, or an undulating non-linear curve alternating back and forth in alternating directions of the tread width.
  • the tread elements 28 are arranged into one of five (5) different ribs 30 comprising shoulder ribs 30s and intermediate ribs 30i, where each rib comprises an array of tread elements 28 arranged to extend circumferentially substantially around the tire in a direction of the tread length.
  • the each of the pair of shoulder ribs 30s are bounded by a lateral side 21 of the tread width W20 and a discontinuity 26A, which comprises a longitudinal groove in the embodiment shown.
  • Intermediate ribs 30j are bounded on both sides by a pair of spaced-apart longitudinal discontinuities 26B, which comprise longitudinal grooves or sipes in the embodiment shown.
  • FIG. 1 illustrates a 5-rib tire
  • the methods described herein can be utilized with tires having more or less ribs than tire 10.
  • one or more tread elements are arranged to provide a non-rib tread, where no ribs are formed with the one or more tread elements.
  • both the first and second longitudinally-spaced sides 32A, 32B extend in a direction of the tread thickness T20, where, for each of the one or more tread elements 28, the first longitudinal side 32A is oriented at an average radial first-side angle ⁇ (inclination angle) relative to the depthwise direction of the tread (that is, in a direction of the tread thickness) and the second longitudinal side 32B is oriented at an average radial second-side angle ⁇ (inclination angle) relative to the depthwise direction of the tread.
  • These average radial first- side and second-side angles ⁇ , ⁇ are each taken as an average of the corresponding angle over the full height H 32 of the corresponding first and second longitudinal-spaced side 32A, 32B along the full length L 32 of the corresponding first and second longitudinal-spaced side for a tread element.
  • the tread 20 is configured to rotate in a direction of rotation R comprising one of opposing directions of the tread length, a positive average radial first-side angle ⁇ orientation and a positive radial second-side angle ⁇ orientation, or a positive angle alone (regardless as to being an average angle), is obtained when the respective first longitudinally-spaced side 32A and the second longitudinally- spaced side 32B are each increasingly inclined in the direction of tread rotation as each respective first longitudinally-spaced side and second longitudinally-spaced side extend in a direction of the tread thickness towards the outer, ground-engaging side of the tread.
  • a portion of the first or second side may include a negative or positive radial angle so long as the average radial angle for each side is positive. It is appreciated that, for any configuration described herein, in particular embodiments, the average radial first-side angle may be different than the average radial second-side angle or, in other embodiments, the average radial first-side angle may be substantially equal to the average radial second-side angle.
  • an average radial inclination angle comprising a combined average of the average first radial side-angle ⁇ and the second side-angle ⁇ for all of the one or more tread elements 28 along the first and second longitudinally-spaced sides is substantially greater than zero.
  • the average radial inclination angle it is not the average of only the average radial first-side angle for all of the one or more tread elements, it is not the average radial second-side angle for all of the one or more tread elements, and it is not the average of both average radial first- side and second-side angles for each of the one or more tread elements. Instead, it is the combined average of the average radial first-side and second-side angles for the total first and second longitudinally-spaced sides for all of the one or more tread elements. It is appreciated that any one of the average radial first-side angle ⁇ and the average radial second-side angle ⁇ may be negative so long as the average radial inclination angle is positive and substantially greater than zero.
  • both the average radial first-side angle ⁇ and the average radial second-side angle ⁇ are substantially greater than zero (0), for the substantial length of each first and second side, respectively.
  • the average radial inclination angle is an average for all of the tread elements arranged long a tire tread.
  • both the first and second longitudinally-spaced sides 32A, 32B extend predominantly in a direction of the tread width W20 but also in a direction of the tread length L 2 o, where, for each of the one or more tread elements 28, the first longitudinal side 32A is oriented at an average axial first- side angle CCA (inclination angle) relative to the widthwise direction of the tread (that is, in the direction of the tread width) and the second longitudinal side 32B is oriented at an average radial second-side angle ⁇ XB (inclination angle) relative to the widthwise direction of the tread.
  • CCA average axial first- side angle
  • ⁇ XB inclination angle
  • first-side and second-side angles CCA, a B are each taken as an average of the corresponding angle over the full length L 32 of the corresponding first and second longitudinal-spaced side 32A, 32B along the full height H 32 of the corresponding first and second longitudinal-spaced side for a tread element.
  • Line 32 avg represents the average linear path along with any longitudinal side 32A, 32B extends along the length L 32 of each such side, since each such side may extend along any non-linear path in a direction of the side length and/or height H 32 . It is noted that in embodiment shown in FIGS.
  • the average axial first-side and second-side angles OCA, a B in the center rib 30, 30i are negative angles, while the average axial first-side and second-side angles measured in the adjacent intermediate ribs 30, 30i are positive angles. It is contemplated that, in providing a positive average axial angle, a portion of the first or second side may include a negative or positive axial angle so long as the average axial angle for each side is positive, and vice versa. It is appreciated that, for any configuration described herein, in particular embodiments, the average axial first-side angle may be different than the average axial second-side angle or, in other embodiments, the average axial first-side angle may be substantially equal to the average axial second-side angle.
  • an average axial inclination angle comprising a combined average of the average first radial side-angle CXA and the second side- angle OCB for all of the one or more tread elements 28 along the first and second longitudinally-spaced sides is substantially non-zero.
  • the average radial inclination angle is not the average of only the average axial first-side angle for all of the one or more tread elements, and it is not the average radial second-side angle for all of the one or more tread elements or the average of both average radial first-side and second-side angles for each of the one or more tread elements.
  • the average axial first-side angle ⁇ XA and the average axial second-side angle ⁇ B may be positive or negative so long as the average axial inclination angle is non-zero. Therefore, in particular embodiments, it is appreciated that both the average axial first-side angle OCA and the average axial second-side angle ⁇ x B are substantially non-zero, for the substantial length of each first and second side, respectively.
  • the average axial inclination angle is an average for all of the tread elements arranged along a tire tread.
  • the one or more tread elements comprise intermediate tread elements 28i, such that the average inclination angle is an average of all of the one or more intermediate tread elements.
  • the average radial inclination angle and the average axial inclination angle are each an average of all intermediate tread elements of tread.
  • one or more intermediate ribs of the plurality of ribs may have a negative average radial inclination angle, so long as the average radial inclination angle for the plurality of intermediate tread elements is substantially greater than zero.
  • the one or more intermediate ribs of the plurality of ribs may have a positive or negative average axial inclination angle, so long as the average axial inclination angle for the plurality of intermediate tread elements is substantially nonzero.
  • an average rib radial inclination angle comprising a combined average of the average radial first side-angle and the radial second side-angle for all of the one or more tread elements forming the respective intermediate rib along the first and second lateral sides is substantially greater than zero.
  • an average rib axial inclination angle comprising a combined average of the average axial first side-angle and the axial second side-angle for all of the one or more tread elements forming the respective intermediate rib along the first and second lateral sides is substantially non-zero.
  • an average rib radial inclination angle comprising a combined average of the average radial first side-angle and the radial second side-angle for all of the one or more tread elements forming the respective rib along the first and second lateral sides is substantially greater than zero and an average rib axial inclination angle comprising a combined average of the average axial first side-angle and the axial second side-angle for all of the one or more tread elements forming the respective rib along the first and second lateral sides is substantially non-zero.
  • a rib may have an average radial inclination angle that is negative so long as the average of the average radial inclination angle for all ribs is substantially greater than zero and that a rib may have an average axial inclination angle that is positive or negative so long as the average of the average axial inclination angle for all ribs is substantially non-zero.
  • the average radial inclination for each of the plurality of ribs is substantially greater than zero.
  • substantially greater than zero means substantially equal to 5 degrees or more, 5 to 30 degrees, 10 to 30 degrees, 10 to 20 degrees, or 15 degrees. Other ranges of angles are also discussed herein, in other embodiments, that are also substantially greater than zero.
  • substantially non-zero means substantially greater or substantially less than zero, and in particular embodiments, substantially non-zero is equal to 20 to 45 degrees, in absolute value, which means equal to 20 to 45 degrees or -20 to -45 degrees.
  • tread elements where the average angle of the radial first-side angle and/or radial second-side angle is substantially greater than zero and where the average angle of the axial first-side angle and/or axial second-side angle is substantially non-zero, or where each are within the ranges otherwise discussed herein, a reduction in longitudinal driving forces is obtained, which in turn reduces slip and wear rate. And if the tire is less round, in particular embodiments, heel and toe wear is reduced or an increase avoided.
  • any average radial first-side angle and/or radial second-side angle and any average axial first-side angle and/or axial second-side angle may be increased or decreased as necessary to better reduce the slip for the targeted frequency or intensity of driving or acceleration.
  • either or both of the average radial first-side angle and the average radial second-side angle, or the average angle as described previously in different embodiments is substantially equal to 5 to 18 degrees and/or either or both of the average axial first-side angle and the average axial second-side angle, or the average angle as described previously in different embodiments, is substantially equal to 20 to 45 degrees, in absolute value.
  • tread elements arranged on a tread comprise tread elements having the particular leading and/or trailing side inclinations as described above.
  • a tire footprint FP is shown, the footprint having a variable length Lpp, which decreases from a maximum L FP , max to a minimum Lpp, m in in a direction of the footprint width WFP (that is, in a widthwise direction) of the footprint, where the net decrease in length between maximum and minimum is identified as A FP .
  • tire treads being characterized as having the average inclination angles described herein, for any one or more tread elements, are tires having footprints characterized as having a net decrease or change in length between maximum and minimum A FP , which, as expressed as a ratio change, is equal to or less than 1.20 or 120%, or, in yet other embodiments, 1.25 or 125% or less. Greater ratio changes may be acceptable in other embodiments.
  • a lateral profile for each of the leading edge LE and trailing edge TE of the footprint also has a drop in length corresponding to the decrease in footprint length A FP as each extends in a direction of the footprint width W F p, which, in the embodiment shown, is equal to approximately one half of the change in footprint length A FP . It is appreciated that a decrease in footprint length may vary as desired for different tires with different footprint shapes, as the footprint shown is provided for exemplary purposes only, as a tire may have a footprint of any desired shape and size. For a given width W F p, the greater the change in length or drop, the rounder the profile.
  • the roundness of a tire footprint may change due to a variety of factors.
  • One primary factor is the lateral profile of the outer, ground-engaging side of the tread.
  • a molded or inflated lateral profile of the outer, ground-engaging side 22 is defined by a radius r extending from the outer, ground- engaging side to the rotational axis A of the tire, whereby for a lateral profile P, the radius r decreases from a maximum radius r ma x to a minimum radius r m i n as the profile extends laterally (that is, in a direction of the tread width W 20 ) from a widthwise tread centerline CL in each lateral direction of the tread.
  • the widthwise centerline CL extends along a plane extending in both a direction of the tread thickness T 20 and a direction of the tread length L 2 o centered between first and second lateral sides of the tread, and which is normal to the rotational axis A of the tire when the tread forms a portion of the tire.
  • the radius r is a maximum at the tread widthwise centerline CL, and is a minimum at each shoulder 21s or at each lateral side 21 of the tread, although different configurations of decreasing radius may be employed.
  • the difference between the maximum r max and the minimum r m j consumer is commonly referred to as shoulder drop A P .
  • shoulder drop A P For a given tread width W 20 , the greater the shoulder drop, the rounder the profile, assuming all other factors remain constant.
  • the drop in lateral profile P may also be associated with a nominal section width Ws of the tire, which is the nominal distance between opposing sidewalls 12.
  • the average angles described herein for average radial first-side angles and radial second-side angles and/or average axial first- side angles and axial second-side angles are applicable to tire treads having a roundness factor substantially equal to or greater than 0.90, or equal to or greater than 0.92 or equal to or greater than 0.94 in other embodiments, where the roundness factor is equal to 1 minus the ratio of the shoulder drop A P to a nominal section width Ws of a tire (that is, the roundness factor is equal to 1 - A P /Ws), and where the shoulder drop is measured as the difference between the radius r taken at the tread centerline CL (or at a location of maximum radius i max) and a location along the lateral tread profile P taken at 83% of a nominal section width Ws of the tire.
  • the shoulder drop A P is equal to or less than 6 mm, such as for a tire having a nominal section width of a 205 mm. In other embodiments, the shoulder drop is between 80 and 95% of the nominal section width Ws, as understood by one of ordinary skill according to the Tire and Rim Association ("TRA") depending upon the series or aspect ratio of a particular tire.
  • TRA Tire and Rim Association
  • the reduction of longitudinal forces may further increase the braking longitudinal forces generated by tread elements located closer to the shoulders, which may lead to increased slip and therefore increased heel and toe wear - even while reducing slip and heel and toe wear at or nearer the tread widthwise centerline.
  • the average radial and/or axial first/second side angle for a tire tread is reduced, to counteract or reduce the generation of any negative longitudinal forces at locations of reduced footprint length.
  • the average radial first/second-side angle is obtained by averaging of all average radial first-side angles ⁇ (not shown, see FIG. 2) and all average radial second-side angles ⁇ (not shown, see FIG. 2), together, for all tread elements on the tire tread.
  • the average axial first/second-side angle is obtained by averaging of all average radial first-side angles OCA (not shown, see FIG. 5) and all average axial second-side angles ⁇ XB (not shown, see FIG. 5), together, for all tread elements on the tire tread.
  • the average is only taken for all intermediate tread elements.
  • the average is taken for each rib, which may comprise only intermediate ribs or both intermediate and shoulder ribs.

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

Abstract

L'invention concerne, dans des modes de réalisation, une bande de roulement de pneumatique, un pneumatique comprenant la bande de roulement de pneumatique, ainsi que des procédés de réduction de l'usure de la bande de roulement sur un pneumatique. Des modes de réalisation particuliers de la bande de roulement comprennent une pluralité d'éléments de bande de roulement, pour chaque élément de la pluralité d'éléments de bande de roulement, un angle d'inclinaison radial moyen comprenant une moyenne combinée d'un angle de premier côté radial moyen et d'un angle de second côté radial moyen pour l'ensemble de la pluralité d'éléments de bande de roulement le long des premier et second côtés espacés sur le plan longitudinal étant sensiblement supérieur à zéro. De plus, concernant la pluralité d'éléments de bande de roulement, un angle d'inclinaison axial moyen, comprenant une moyenne combinée de l'angle de premier côté axial moyen et d'un angle de second côté axial moyen pour l'ensemble des un ou plusieurs éléments de bande de roulement le long des premier et second côtés espacés sur le plan longitudinal, est sensiblement supérieur à zéro.
PCT/US2016/059351 2015-10-30 2016-10-28 Bandes de roulement de pneumatique ayant des éléments de bande de roulement avec des côtés avant et arrière inclinés sur le plan radial et sollicités sur le plan axial WO2017075371A1 (fr)

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USPCT/US2015/058470 2015-10-30
PCT/US2015/058470 WO2017074463A1 (fr) 2015-10-30 2015-10-30 Bandes de roulement comprenant des éléments de bande de roulement présentant des côtés d'attaque et de fuite radialement inclinés et axialement sollicités

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PCT/US2015/058470 WO2017074463A1 (fr) 2015-10-30 2015-10-30 Bandes de roulement comprenant des éléments de bande de roulement présentant des côtés d'attaque et de fuite radialement inclinés et axialement sollicités
PCT/US2016/059372 WO2017075388A1 (fr) 2015-10-30 2016-10-28 Bandes de roulement de pneumatique ayant des éléments de bande de roulement avec des côtés avant et arrière inclinés sur le plan radial et sollicités sur le plan axial
PCT/US2016/059351 WO2017075371A1 (fr) 2015-10-30 2016-10-28 Bandes de roulement de pneumatique ayant des éléments de bande de roulement avec des côtés avant et arrière inclinés sur le plan radial et sollicités sur le plan axial

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PCT/US2016/059372 WO2017075388A1 (fr) 2015-10-30 2016-10-28 Bandes de roulement de pneumatique ayant des éléments de bande de roulement avec des côtés avant et arrière inclinés sur le plan radial et sollicités sur le plan axial

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3768535A (en) * 1971-12-03 1973-10-30 E Holden Tire tread
US5200008A (en) * 1991-02-07 1993-04-06 Michelin Recherche Et Technique Radial tire tread and method of mounting a tire with said tread
US5944082A (en) * 1992-12-30 1999-08-31 Michelin Recherche Technique S.A. Tire tread to compensate residual aligning torque
US5960845A (en) * 1993-07-23 1999-10-05 Sumitomo Rubber Industries, Ltd. Pneumatic tire

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB727207A (en) * 1952-06-24 1955-03-30 Goodrich Co B F Improvements in or relating to a high speed tire
DE3146362A1 (de) * 1981-02-23 1982-09-02 The General Tire & Rubber Co., 44329 Akron, Ohio Reifen mit verbesserter laufflaeche
JPH05178026A (ja) * 1992-01-07 1993-07-20 Toyo Tire & Rubber Co Ltd タイヤのプライステア残留コーナリングフォースを制御する方法および車の直進性に優れたタイヤ
FR2956354A1 (fr) * 2010-02-12 2011-08-19 Michelin Soc Tech Pneumatique pour vehicules a deux roues comportant une bande de roulement presentant des incisions.

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3768535A (en) * 1971-12-03 1973-10-30 E Holden Tire tread
US5200008A (en) * 1991-02-07 1993-04-06 Michelin Recherche Et Technique Radial tire tread and method of mounting a tire with said tread
US5944082A (en) * 1992-12-30 1999-08-31 Michelin Recherche Technique S.A. Tire tread to compensate residual aligning torque
US5960845A (en) * 1993-07-23 1999-10-05 Sumitomo Rubber Industries, Ltd. Pneumatic tire

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WO2017075388A1 (fr) 2017-05-04

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