Patent Publication Number: US-2021178820-A1

Title: Pneumatic tire

Description:
FIELD OF THE INVENTION 
     This invention relates to a pneumatic tire having a carcass and a belt reinforcing structure, and, more particularly, to radial ply tires for use in aircraft, trucks and other high load applications. 
     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 
     The invention provides in a first aspect a pneumatic tire comprising a tread, a carcass and a belt structure interposed between the carcass and the tread. The belt structure includes a first and second working belt, wherein a low angle belt is positioned between the first and second working belts, and wherein the low angle belt has an angle less than 10 degrees. The second working belt is located radially outward of the first working belt and the low angle belt, and has a first lateral end and a second lateral end. A first lateral belt is located adjacent the first lateral end of the second working belt, and a second lateral belt is located adjacent the second lateral end of the second working belt. 
     Definitions 
     “Apex” means a non-reinforced elastomer positioned radially above a bead core. 
     “Aspect ratio” of the tire means the ratio of its section height (SH) to its section width (SW) multiplied by 100% for expression as a percentage. 
     “Axial” and “axially” mean lines or directions that are parallel to the axis of rotation of the tire. 
     “Bead” means that part of the tire comprising an annular tensile member wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes, toe guards and chafers, to fit the design rim. 
     “Bias ply tire” means a tire having a carcass with reinforcing cords in the carcass ply extending diagonally across the tire from bead core to bead core at about a 25-50 degree angle with respect to the equatorial plane of the tire. Cords run at opposite angles in alternate layers. 
     “Carcass” means the tire structure apart from the belt structure, tread, undertread, and sidewall rubber over the plies, but including the beads. 
     “Circumferential” means lines or directions extending along the perimeter of the surface of the annular tread perpendicular to the axial direction. 
     “Chafers” refer to narrow strips of material placed around the outside of the bead to protect cord plies from the rim, distribute flexing above the rim, and to seal the tire. 
     “Chippers” mean a reinforcement structure located in the bead portion of the tire. 
     “Cord” means one of the reinforcement strands of which the plies in the tire are comprised. 
     “Extensible” means a cable having a relative elongation at break of greater than 0.2% at 10% of the breaking load, when measured from a cord extracted from a cured tire. 
     “Equatorial plane (EP)” means the plane perpendicular to the tire&#39;s axis of rotation and passing through the center of its tread. 
     “Flipper” means a reinforced fabric wrapped about the bead core and apex. 
     “Footprint” means the contact patch or area of contact of the tire tread with a flat surface at zero speed and under normal load and pressure 
     “Innerliner” 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. 
     “Net-to-gross ratio” means the ratio of the tire tread rubber that makes contact with the road surface while in the footprint, divided by the area of the tread in the footprint, including non-contacting portions such as grooves. 
     “Radial-ply tire” means a belted or circumferentially-restricted pneumatic tire in which the ply cords which extend from bead to bead are laid at cord angles between 65-90 degrees with respect to the equatorial plane of the tire. 
     “Section height” (SH) means the radial distance from the nominal rim diameter to the outer diameter of the tire at its equatorial plane. 
     “Winding” means the pattern of the strip formed in a first revolution of the strip around a tire building drum, tire or core. 
    
    
     
       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  illustrates a partial cross-section through the tire midplane of an exemplary radial tire  10  of the present invention; 
         FIG. 2  illustrates a cross-sectional view of the tire belt package; 
         FIG. 3  illustrates a top view of a first embodiment of belt layup shown on a tire building drum from 0 to 360 degrees of the drum shown; 
         FIG. 4  illustrates a top view of a second embodiment of belt layup shown on a tire building drum from 0 to 360 degrees of the drum shown; 
         FIG. 5  is a cross-sectional view of the tire belt package illustrating the formation of the low angle belt; and 
         FIG. 6  is a second embodiment of a belt package for a radial tire. 
     
    
    
     DETAILED DESCRIPTION OF AN EXAMPLE EMBODIMENT THE INVENTION 
       FIGS. 1-2  illustrates a partial cross-section of an exemplary radial tire  10  which includes a bead portion  23  having a bead core  20  embedded therein, a sidewall portion  16  extending radially outward from the bead portion  23 , and a cylindrical tread portion  25  extending between radially outer ends of the sidewall portions  16 . The tread  25  may include a plurality of ribs  31 , 32  and shoulder lugs  33  with optional grooves  34 , 35 , 36  located between the ribs. The tire  10  includes an inner liner  14  and is reinforced by one or more carcass plies  18  toroidally extending from one bead portion  23  to the other bead portion (not shown). The carcass ply  18  is preferably anchored to the bead core and for example, may wind around each bead core  20  from inside of the tire  10  away from the equatorial plane EP to form a turnup portion  19 . A belt reinforcement package  40  is arranged between the carcass ply  18  and the tread portion  25 . 
     The belt reinforcement package  40 , according to an example embodiment of the present invention, includes a first and second working belt,  41 ,  45 . The first working belt  41  is preferably the radially innermost belt of the belt reinforcement package  40 , and is the widest belt of the belt reinforcement package  40 . Preferably, the first working belt  41  has a belt width substantially equal to the tread arc width. The breaker angle of first working belt  41  is between about 12 and 45 degrees, preferably with a left orientation, more preferably in the range of about 19 to about 30 degrees. The belt angles are measured with respect to the circumferential direction. 
     The second working belt  45  is located radially outward of the first working belt. The second working belt  45  preferably has a width in the range of 30% to 50% of the tread arc width. The second working belt  45  has a breaker angle between about 12 and 45 degrees, preferably with a right orientation, more preferably in the range of about 19 to about 30 degrees. The second working belt  45  is preferably made of the same wire as belt  41 , and has the same construction with the same but opposite angular orientation as  41 . 
     The first and second working belts  41 , 45  are preferably made of steel. The % elongation at 10% of breaking load of the first and second working belts  41 , 45  may range from about 0.18 to about 0.26. Preferably, the working belts  41 , 45  are extensible, so that the % elongation at 10% of breaking load is greater than 0.2. The % elongation is measured on a cord extracted from a vulcanized tire. 
     The belt package  40  further includes a low angle belt  43 , that is preferably helically wound and has a belt angle of less than 10 degrees, and more preferably less than 5 degrees. The low angle belt  43  is preferably located between the first and second working belts, in other words, radially outward of the first working belt  41 , and radially inward of the second working belt  45 . The low angle belt  43  preferably narrower in axial width than the first working belt  41 . The low angle belt  43  is preferably formed from a reinforced strip of one or more cords, wherein the width of the strip is in the range of 3 to 20 mm, and more preferably in the range of 3 to 8 mm. The low angle belt structure  39  may be formed from using any of the patterns as further described below. 
     The second working belt  45  is located radially outward of the low angle belt  43 , and has a first lateral end  46  that is located adjacent a first lateral end belt  48 . The second working belt  45  has a second lateral end  50  that is located adjacent a second lateral end belt  52 . The first and second lateral end belts  48 , 52  each have a belt angle of less than 10 degrees, and more preferably less than 5 degrees. 
       FIG. 5  illustrates an alternate embodiment of the invention, wherein the lateral belt  48  and  52  are integrally formed with the low angle belt  43 , as illustrated. 
     The belt structure  40  further comprises a third working belt  60  which is the radially outermost belt. The third working belt preferably has a breaker angle between about 12 and 45 degrees, preferably with a right orientation, more preferably in the range of about 19 to about 30 degrees. The third working belt  45  is preferably made of the same wire as belt  41 , and has the same construction with the same but opposite angular orientation as  41 . 
     A first embodiment of a belt layup for the low angle belt  43  is shown in  FIG. 3 . This pattern spirally winds a rubberized strip of one or more parallel cords on a tire building drum or former. Preferably, the strip uses at least three reinforcement cords, and preferably has a strip width of 3 to 30 mm, and more particularly 5 to 7 mm. The low angle belt is formed by starting the strip at a first drum end or left shoulder of the tire building drum at a zero degree angle with the circumferential direction, wherein the strip laterally shifts over one strip width after 360 degrees rotation of the drum. The strip is then wound on the drum as the drum rotates to the opposite shoulder or side of the drum. The strips may be wound with a gap between windings or overlapped. The strip may be wound in such a manner to form a single or double layer forming a low angle belt. 
     A second embodiment of the low angle belt  43  construction is shown in  FIG. 4 . Starting at the center line of the drum, a strip of reinforcement cords is wrapped onto the building drum to the right shoulder of the drum at a first angle, wherein the first angle is less than 10 degrees with the circumferential direction. The strip is then continuously wound in a zigzag manner from the first shoulder to the second shoulder of the drum at a second angle, wherein the second angle is negative and less than 10 degrees with the circumferential direction, and then back to the center. A positive gap or spacing may be placed in between consecutive adjacent segments of the strip, acting like a separator. 
     The belt width of the low angle belt is preferably in the range of about 70% to about 80% of the tread arc width, and even more preferably in the range of 73-77%. The low angle belt  39  may be steel, and may be formed of high elongation reinforcements or extensible reinforcements. The reinforcements may be a high elongation construction such as, for example, 3×7×0.22 HE, and having an EPI of about 14. The high elongation wire may have a % elongation at 10% of the breaking load ranging from about 1.7-2.05% for a bare, green cord. The high elongation wire may have a % elongation at 10% of the breaking load ranging from about 0.45-0.68% taken from cured tire. Another example of a cord construction suitable for the invention is made of steel having a 4×7×.26 HE construction, with an EPI of 18. 
     The aspect ratio of the tire described above may vary. The aspect ratio is preferably in the range of about 50 to about 90. The tire may have a net to gross ratio in the range of about 70 to about 90, more preferably in the range of about 74 to about 86, more preferably about 78 to 84. 
       FIG. 6  illustrates a third embodiment of the tire of the present invention. The tire  100  a radially inner first working belt  110  which is the widest belt of the belt package, and has a width about equal to the tread arc width. A low angle belt layer  120  is located radially outward of the first working belt  110 . The low angle belt layer  120  is formed from a rubberized strip  121  of parallel reinforcement cords, and having a strip width in the range of 5 mm to 20 mm, more preferably about 10 mm to 15 mm. The low angle belt layer  120  has overlapping strips in the axially outer ends  122  of the belt, and a central portion  124  with non-overlapping strips. A second working belt  130  is located radially outward of the low angle belt layer  120 , and is the narrowest belt of the belt package. Preferably, the second working belt  130  has an axial belt width equal to the axial width of the central portion  124  of the low angle belt layer  120 . The tire  100  may further include an optional third working belt  140 . The third working belt  140  is wider than the second working belt, and narrower than the first working belt  110  and narrower than the low angle belt  120 . 
     Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.