Patent Publication Number: US-2021178822-A1

Title: Truck tire

Description:
FIELD OF INVENTION 
     The invention relates in general to pneumatic tires, and more particularly for vehicles such as trucks. 
     BACKGROUND OF THE INVENTION 
     The commercial truck market is moving towards an increase in overall vehicle weight, which is due in part to the increase in weight of the motor and equipment. The increase in overall vehicle weight requires a tire capable of handling the additional loading. Thus, a tire with improved crown durability and increased load carrying capacity is desired. 
     SUMMARY OF THE INVENTION 
     A first aspect of the invention is a pneumatic tire for use on trucks, the tire comprising a tread and a belt structure located radially inward of the tread, the belt structure including a pair of working belts, wherein the working belts are reinforced plies each comprising parallel reinforcement elements, wherein the angle of the reinforcement elements in the respective working belt ranges from 12 degrees to 35 degrees from the circumferential direction, wherein the belt structure further includes a belt positioned between the working belts comprising parallel reinforcement elements angled at less than 5 degrees from the circumferential direction, and wherein there is a split belt which is the radially outermost belt, and is positioned radially inward of a groove of the tread. 
     In a preferred aspect of the invention, the working belts are formed of extensible reinforcement elements, and more preferably, wherein the reinforcement elements are extensible having an elongation at 10% of the breaking load greater than 0.2% when measured at the reinforcement elements extracted from a cured tire, and wherein the extensible reinforcement elements are wires comprising steel or hybrid cords, formed of high elongation wire having a % elongation at 10% of breaking load greater than 0.4% when taken from wire from a cured tire. 
     Definitions 
     “Aspect Ratio” means the ratio of a tire&#39;s section height to its section width. 
     “Axial” and “axially” mean the lines or directions that are parallel to the axis of rotation of the tire. 
     “Bead” or “Bead Core” mean generally that part of the tire comprising an annular tensile member, the radially inner beads are associated with holding the tire to the rim being wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes or fillers, toe guards and chafers. 
     “Belt Structure” or “Reinforcing Belts” means at least two annular layers or plies of parallel cords, woven or unwoven, underlying the tread, unanchored to the bead. 
     “Carcass” means a laminate of tire ply material and other tire components cut to length suitable for splicing, or already spliced, into a cylindrical or toroidal shape. Additional components may be added to the carcass prior to its being vulcanized to create the molded tire. 
     “Circumferential” means lines or directions perpendicular to the axial direction. 
     “Cord” means one of the reinforcement strands, including fibers, which are used to reinforce the plies. 
     “Extensible” means a cable, cord, wire or reinforcement having an elongation at 10% of the breaking load greater than 0.2%, when measured from a cord extracted from a cured tire. 
     “Inner Liner” means the layer or layers of elastomer or other material that form the inside surface of a tubeless tire and that contain the inflating fluid within the tire. 
     “Ply” means a cord-reinforced layer of elastomer-coated, radially deployed or otherwise parallel cords. 
     “Radial” and “radially” mean directions radially toward or away from the axis of rotation of the tire. 
     “Radial Ply Structure” means the one or more carcass plies or which at least one ply has reinforcing cords oriented at an angle of between 65° and 90° with respect to the equatorial plane of the tire. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described by way of example and with reference to the accompanying drawings in which: 
         FIG. 1  is a cross-sectional view of a first embodiment of a tire of the present invention; and 
         FIG. 2  is a close-up view of the belt package of the tire of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a first embodiment of a pneumatic tire, suitable for use as a truck tire. The tire  10  has a tread  12  with a non-skid depth D. The tire tread  12  may comprise a plurality of circumferentially continuous ribs, which may vary, but are shown for example as ribs  31 ,  32  and  33 . Positioned between each rib is a circumferential groove  34 ,  35 ,  36 , which are preferably continuous. The tread may also comprise optional sipes (not shown). The tread pattern is not limited to same, and may comprise, for example, a plurality of blocks and grooves (not shown). 
     The tire  10  further comprises a casing  14  which includes two opposed sidewalls  16  which extend down from the tread  12  to the bead area. The casing of the tire may include an inner liner  24  which is typically formed of halobutyl rubber which forms an air impervious barrier. The tire casing  14  further includes one or more radial plies  18  extending from the tread, down the sidewall to the tire bead  20 . Preferably the radial ply  18  is wrapped about or otherwise secured to each annular bead  20 . In the embodiment illustrated and not limited to same, there is only one ply  18  and it is wrapped around the bead in an inside out manner such that the ply ending  19  is located axially outward and radially outwards of the bead. The beads  20  may be any desired shape, but in this embodiment, it is shown as a hexagonal configuration with steel filaments. 
     The tire may further optionally include an apex  21  which may be shaped like a triangle. The ply turnup in the bead area may be optionally reinforced with a chipper  23  wrapped about the bead ply  18 . 
     The tire  10  further includes a belt package  50  which is located between the tread and the one or more plies  18 . The belt package comprises layers of reinforcement. The ply  18  and the belt reinforcing structure  50  are made from cord reinforced elastomeric material, wherein the cords are typically steel wire or polyamide filaments and the elastomer preferably being rubber. 
     The belt reinforcing package  50  may include an optional radially inner transition belt  52 . The transition belt  52  preferably is the narrowest belt of the structure  50 . The transition belt  52  has a belt width which preferably ranges from 0.6 to 0.9 or 0.65 to 0.85 of the tread arc width. The transition belt  52  preferably has an orientation that has an angle of between 45 to 70 degrees, preferably right. The transition belt  52  is preferably made of ultra tensile steel with a construction of 3+2×0.35. 
     The belt reinforcing structure  50  further includes a pair of working belts,  54 ,  56 . The first working belt  54  is located radially inwards of the second working belt  56 , and is preferably the widest belt layer of the belt reinforcing structure  50 . The first working belt  54  has a width which is preferably equal or, about equal, i.e. ±5%, to the tread arc width. The breaker angle of belt  54  is between 16 and 30 degrees, preferably with a right orientation, more preferably in the range of 19 to 25 degrees. Belt  54  is preferably made of high elongation wire, which is has a % elongation at 10% of breaking load of greater than 0.4%, alternatively greater than 0.6% or 0.8%, as measured from a cord taken from a cured tire. Alternatively, the cable has a % elongation at 10% of breaking load of greater than 1.7% when measurement is performed on a bare wire sample that has not been vulcanized in a tire. For example, the belt may be formed of wire having a wire construction of 3×7×, 3×4×, 4×4×. Preferably the wire has a construction of 3×7×0.22 HE (HE=high elongation steel wire). The EPI may range from 8 to 14. The wire may be a hybrid cord or a steel wire. 
     The second working belt  56  is the second member of the working belt pair. The second working belt  56  has a width less than the width of the first working belt  54 , and is preferably radially outward of the first working belt  54 . Preferably, the second working belt  56  has a width less than the width of belt  54  by a step off, which may range from 10 to 20 mm. Belt  56  has a breaker angle between 12 and 35 degrees, preferably with a left orientation, more preferably in the range of 19 to 25 degrees. Belt  56  is preferably made of high elongation wire. Preferably, the high elongation wire is the same as the wire of the first working belt  54 . More preferably, the wire has the same construction with the same but opposite angular orientation as the wire of belt  54 . 
     The belt structure  50  further comprises a fourth belt  58  which is preferably located between the working pair belts,  54 ,  56 . The fourth belt  58  is located between belts  52  and  54 . The fourth belt  58  has reinforcements that are oriented circumferentially at 5 degrees or less, preferably 2 degrees or less, more preferably 0 degrees. The fourth belt  58  has a belt width less than the belt width of the working belts  54 , 56 . 
     The fourth belt  58  is preferably formed from spirally winding a rubberized strip of one or more cords. Preferably, the strip has 3, 4 or 5 steel cords, and has a width in the range of 5-10 mm, more preferably about 4-6 mm. The belt  58  has a width sized to avoid compression in the shoulder area. The belt width of fourth belt  58  is preferably in the range of 70% to 80% of the tread arc width, and even more preferably in the range of 73-77%. The fourth belt  58  is preferably wide enough to decrease the strain cycles in the breaker wedge, and is just stopped before the shoulder area to avoid zero degree wire compression and a too round footprint. 
     The belt structure of fourth belt  58  may be formed of high tensile steel, and have a % elongation at 10% of breaking load of 0.18 or more, for measurements taken from a cured tire. For measurements taken from bare cords, the % elongation at 10% of breaking load is 0.2 or more. Alternatively, the fourth belt may be formed of non-metal reinforcements such as aramid, carbon fiber, or polyketone or POK. 
     The belt structure may further include a first and second split belt  62 , located on each side of the tire and having a narrow axial width to be positioned radially inward of the axially outermost shoulder groove. The split belt  62  preferably is the narrowest belt and is the radially outermost belt of the belt reinforcement structure. Preferably, the split belt  62  has a width greater than or equal to the axial width of the groove and sufficient to be positioned radially inward of the axially outermost shoulder groove  36  on each side of the tire. The axial width of the split belt  62  may be preferably in the range of two to four times the axial width of the groove. Preferably, the split belt  62  has the same angle and orientation as the adjacent belt  56 . 
     The aspect ratio of the tire described above may vary. The aspect ratio is preferably in the range of from 0.4 to 0.6. The tire may have a net to gross ratio in the range of 70 to 90, more preferably in the range of 74 to 86, more preferably a 78 to 84.