Patent Publication Number: US-2005139305-A1

Title: Tire with enhanced sidewall

Description:
FIELD OF THE INVENTION  
      This invention relates to tires for heavy-duty use applications, particularly to a pneumatic tire having at least one, preferably the outer, sidewall formed of extra thickness for heavy-duty wear purposes.  
     BACKGROUND OF THE INVENTION  
      Pneumatic tires used in heavy-duty applications, e.g., on mining machines, forklifts, and other industrial equipment, and the like, often have an extra thick tread section. Nevertheless, they typically have relatively thin sidewalls, for example, of only ⅜ to {fraction (1/2)} inch thickness. Such heavy duty use tires often encounter severe cuts and damaging blows to the sidewall area, caused by hitting rocks, concrete curbs, warehouse rack frames, pallets, and other pieces of equipment, and obstacles. Thus, the outer sidewall areas on such heavy-duty application tires are often destroyed prematurely, or because of the impact the carcass is damaged to the point of early failure. Further, the outer edge of the associated rim flange on many heavy duty tires is not sufficiently protected by the tire&#39;s sidewall causing the flange to be bent and broken to the point of causing the tire itself to become a “leaker” or unusable.  
      Further yet, a heavy duty use tire&#39;s internal carcass member can be damaged, in the sidewall areas, if not properly protected, thereby rendering a shorter overall life for the carcass, which normally should be able to be re-used and re-treaded several times.  
      Past attempts at heavy-duty application tires did not prove to be commercially satisfactory, i.e., since they did not have sufficient upper sidewall thickness (in the areas nearest the tread), to prevent sidewall tearing problems in that area. Further, in the past there were always inherent difficulties in the thickness (actually “thinness”) of the sidewall in such heavy-duty application tires, i.e., at the very area where a substantial amount of sidewall damage normally occurs.  
     SUMMARY OF THE INVENTION  
      The present invention seeks to overcome the deficiencies in the prior art by providing a non-symmetrical tire having an extra thick sidewall on the outer wall of the tire, ie., the sidewall facing outside and away from the machine on which the tire is mounted. The asymmetrical design is required because of the very close inside tolerances associated with equipment of this type. This thick sidewall of the present invention is intended to be sufficiently flexible to provide a relatively smooth ride for the tire, yet also be sufficiently thick to provide protection for the overall tire and its internal carcass in its working environment.  
      More specifically, the present invention provides a heavy-duty use pneumatic tire with an enhanced thickened sidewall on at least one side of the tire to protect against sidewall wear, with a specifically configured double arch-shaped relief area near the wheel hub&#39;s rim flange to prevent undesired contact during tire use of the thickened sidewalls with the associated metal rim flange. The sidewall&#39;s enhanced thickness portion extends substantially the full vertical height of the tire&#39;s sidewall, i.e., from near the bead to substantially adjacent the tire&#39;s tread area, and further. The uppermost outer edge of the enhanced thickened sidewall portion is formed with a substantially sharp return angle to the upper sidewall area. Further, sufficient so-called “rubber flow through” occurs during the tire molding process in the enhanced sidewall and tread areas with the utilization of breaker plies having less ends per inch than the remaining carcass plies, all to help strengthen and bind the thick sidewall and thick tread portion to the tire&#39;s internal carcass. This is accomplished by using, in the last few uppermost or breaker plies, a lesser number of inch ends of fibers per ply, and to have the breaker ties extend substantially into the sidewall area. This, in turn, results in also having in essence a tread area on the upper sidewall region. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The means by which the foregoing and other aspects of the present invention are accomplished and the manner of their accomplishment will be readily understood from the following specification upon reference to the accompanying drawings, in which:  
       FIG. 1  depicts in cross section the sidewalls, carcass profile, and outer tread portions of a pneumatic tire made in accordance with the present invention;  
       FIG. 2  depicts another cross section view of the tire of  FIG. 1 , depicting the enhanced sidewall with associated carcass and ply configuration; and  
       FIG. 3  is a top plain view of a portion of the tire, further depicting the thickness of the thick sidewall. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Having reference to the drawings, wherein the like reference numerals indicate corresponding elements, there is shown, in  FIG. 1  (which is drawn as a tire mold drawing but which accurately represents the finished tire) a cross section view of a pneumatic tire made in accordance with one aspect of the present invention, the tire being generally denoted by reference numeral  20 .  
      Tire  20  includes an inner sidewall portion  22  (shown to the right in  FIG. 1 ), an outer sidewall portion  24  (to the left in  FIG. 1 ), and an outer or uppermost tread portion  26  formed between the two sidewalls. A hidden (in  FIG. 1 ) portion of the tread  26  is depicted in phantom by reference numeral  28  and the tread also appears in  FIG. 2 . However, no specific tread design for tire  20  is claimed as part of the present invention. The lower portion of the respective sidewalls  22 ,  24  terminate respectively in flange walls  30 ,  32 , which between them form the opening  34  to allow mounting of the tire  20  on a wheel or rim (not shown) having a rim flange  47 . The present invention is directed, in part, to the enhanced, i.e., thickened, sidewall present along substantially the vertical extent of outer sidewall portion  24 , as denoted by reference letter A. More specifically, outer sidewall portion  24 , starting at the tread portion  26 , includes an upper sidewall portion  36 , a sharp, angled upper sidewall portion  38  and an elongated sidewall portion  40  with a sidewall crown  42  therebetween, and a relief area  43  formed of an outer radius portion  44 , an inner radius portion  46 , and terminating in a lower curved corner bead edge  48 . As seen in  FIG. 1 , the typical hub rim flange  47  provides the mounting environment for the tire  20  of the present invention.  
      Shown generally by reference numeral  50  is the outer profile of the tire&#39;s carcass along outer sidewall  24 . As seen, the thickened portion A of the outer sidewall  24  extends at its lowest point from inner radius portion  46  on through to its upper point at intersection point  39  of the angled sidewall  38 . This results in a substantially thickened outer sidewall, which at its widest point has a thickness (measured from sidewall crown  42  to the outer carcass profile  50 ) designated as thickness “T”.  
      It will be noted that angled sidewall portion  38  is preferably generally linear. However, the elongated sidewall portion  40  is preferably formed with a surface  41  generated by an elongated radius “R”. This results in a smooth curved surface  41  along outer sidewall portion  40 .  
      In one heavy-duty use tire made in accordance with the present invention, having a generally 14.50-15 size, the overall sidewall height, designated by reference letter H 1  in  FIG. 1 , was approximately 10.5 inches; the height H 2  representing the height of the tire from the bead edge  48  to the upper end of upper sidewall  38  was 7.8 inches; the height H 3 , representing the height from the bead edge  48  to the sidewall crown  42 , was 6.8 inches; and height H 4 , representing the height distance between the tire&#39;s bead  32  and intersecting point  45  of elongated sidewall  40  and outer radius portion  44 , was approximately 2.0 inches.  
      Further for that same tire, the width distance, as generally denoted by reference letter D 1  in  FIG. 1 , representing the length of the bead  32  of tire  20 , was 2.2 inches; the width distance D 2  from the tire&#39;s center line (designated by reference letter CL) to the rim flange wall  47 , was 6.2 inches; the width distance D 3  from the tire&#39;s center line CL to the intersection of respective outer and inner radius portions  44 ,  46 , was 6.85 inches; the width distance D 4  from the tire&#39;s center line CL to the intersection of outer radius portion  44  and the lower edge of elongated sidewall  40 , was 6.8 inches; the widest dimension of the tire, namely distance D 5 , running from the tire&#39;s center line CL to the sidewall crown  42 , was 8.1 inches; the width distance D 6  from the tire&#39;s center line CL to the upper edge of angled upper sidewall  38 , was 6.6 inches; and the width distance D 7  from the tire&#39;s center line CL to the upper edge of upper sidewall  36 , was 6.3 inches.  
      As seen then, in that one example of a tire made in accordance to the present invention, the thickness T (between the outer sidewall carcass profile  50  and sidewall crown  42 ) was approximately 2.7 inches. Thus, instead of having a sidewall thickness of only approximately 0.375 inches, as was commonly present in prior art heavy-duty use tires, the sidewall thickness T of a tire made in accordance of the present invention is substantially thicker, and namely by some 2.325 inches. That is approximately a 620% increase in sidewall thickness. Preferably, the thickness T will range from approximately 2.0 inches to 3.5 inches, depending upon the present tire&#39;s sidewall design, its tread design, the tire&#39;s overall size, and the ultimate intended end use for the enhanced sidewall tire in question, such that the extra sidewall thickness T can be between some 433% and 833% greater than the thickness of the normal prior art sidewall.  
      Reference  52  shows the internal carcass profile along the inner sidewall (on the right side of tire  20  of  FIG. 1 ). As seen then, the thickness T (between carcass profile  50  and sidewall crown  42 ), is substantially different and larger than the corresponding thickness T 1  (between inner sidewall carcass profile  52  and the upper edge  56  of the right side&#39;s narrow, angled upper sidewall  58 ). That extra thickness present in outer sidewall  24  causes it to provide substantial protection to tire  20  and its carcass  49  from blows to the outer sidewall as often encountered during normal heavy duty use. That enhanced thickness of the outer sidewall  24  permits, in turn, substantial numbers of re-use and retreadings for the tire carcass  49 . In combination with the thickened sidewall  40 , the relief radius portions  44 ,  46  help prevent the metal rim flange edge  47  from cutting into the outer sidewall  24 .  
      Preferably, the height H 4  ( FIG. 1 ) varies within the range from approximately 1.7 inches to 3.0 inches. This range is chosen so as to prevent the outer edge of rim flange  47  from cutting into the outer sidewall  24 , yet also not be so large that rocks, debris, and other undesirable materials can easily lodge and wedge within the areas of respective outer and inner radius portions  44 ,  46  and rim flange edge  47 . Thus, the lower end of sidewall  24  is sufficiently relieved in thickness, at relief area  43  via the two radius portions  44 ,  46 , to prevent the metal rim flange edge  47  from undesirably cutting into the tire&#39;s thickened sidewall and also from undesirably being bent itself by that thickened sidewall, which can cause tire “leaker” conditions.  
      As seen in  FIG. 1 , the upper extent, i.e., reach, of the enhanced thickened portion A of outer sidewall  24  extends to the full height of distance H 2 , namely, to the height of intersection point  39  (that point between angled sidewall  38  and upper sidewall  36 ). In that manner, the enhanced thickness of outer sidewall  24  extends up into the area of upper sidewall  36 . Preferably, distance H 2  extends to within the range of from approximately 60% to 85% of the radial height H 1  of the tire&#39;s sidewall. This allows there to be substantial sidewall thickness (represented by thickness T) present exactly at the point in the tire&#39;s outer sidewall  24  where the most flexing occurs during heavy duty use. In the prior art tires there was substantial tearing experienced along this general location, as the customary thin sidewalls of prior art tires were unable to sustain extended severe blows and stress at that area. However, the present invention&#39;s enhanced outer sidewall  24 , which has an enhanced thickness A extending up into the upper sidewall, solves this problem. Further yet, the high, thick sidewall  24  of the present invention operates to provide a smooth ride for the heavy duty use tire  20 .  
      It will be understood that the enhanced sidewall of the present invention could also be used with so-called “smooth” heavy-duty tires (not shown) where there is a smooth outer wall instead of a tread portion, such as used in hard rock mining operations. In those instances the thickened sidewall portion A, per distance H 2 , can extend up higher, and to as much as 90% of the radial height of the sidewall, i.e., towards the smooth tread portion.  
      If needed for specific end use situations, it will be understood that both inner and outer sidewalls  22 ,  24  can be formed of thickened sidewall portions (whether both have the same enhanced thickness T, or otherwise), such that the inner sidewall  22 , along with the thickened outer sidewall  24 , can be enhanced and thickened (not shown) to help prevent premature wear of both the sidewalls of the tire.  
      Preferably, the tire&#39;s carcass  49  (with thick and thin sidewall carcass profiles shown generally by reference numerals  50 ,  52  respectively) is formed of several plies of fibers. Such ply fibers are preferably formed of Nylon cord materials. Further, the tire is molded over the carcass  49  in a known manner by use of a molded rubber compound, such as formed of natural rubber, synthetic rubber, carbon black, various other known tire molding chemical materials, and mixtures thereof.  
      As seen in  FIG. 3 , there is shown the special carcass configuration  49  as used for enhanced sidewall tire  20 . Carcass  49  includes a series of turn-up plies  60  which extend from inner end of tire bead  32  up along the outer carcass wall  62  (of enhanced sidewall portion  24 ) and stopping at an upper turn-up ending  64 . These turn-up plies  60 , which extend up enhanced sidewall  24  to a further height them turn-up ending  66  of turn-up plies  68  on inner sidewall  22 , help protect the generally lower half of elongated enhanced sidewall portion  40  of thickened sidewall  24 .  
      Further, a series of breaker plies  70  are laid against the outermost carcass ply  72  and extend (at their rightmost end in  FIG. 3 ) from point B 1  to point B 2  (at their leftmost end in  FIG. 3 ), which is at a point extending over the outermost tun-up ply  60  at upper turn-up ending  64 . That is, instead of being normally centered relative to the tread so as to straddle the outermost carcass ply  72  (as in prior art tires), the breaker plies  70  of the tire  20  of the present invention are formed to cover and protect both the upper tread portion  26  and the generally upper half of enhanced sidewall  24 . As seen, the lowermost portion of sidewall breaker plies  70  overlie the uppermost portion of outer turn-up plies  60 , and hence, cooperate to provide enhanced sidewall  24  with extra protection all along its length.  
      Further yet, the breaker plies  70  are formed to be of lesser ply ends per inch than the other plies making up carcass  49 . That is, breaker plies  70  are preferably formed to contain from 10 to 15 ends per inch, and more preferably, 13 ends per inch, whereas the remaining or innermost plies forming carcass  49  are formed to contain form 20 to 24 ends per inch. Thus, it will be understood that, during tire molding, the lesser-ends-per-inch ply material used for breaker plies  70  allows more so-called “rubber flow through” to occur through and between the breaker plies, i.e., where they are positioned along tread wall and enhanced sidewall portions of carcass  49 . This, in turn, helps better bond the thick sidewall portion  24 , and also thick tread portion  26 , to the carcass  49  during the tire molding process to provide improved tire wear and protection.  
      Overall, the presence of a substantially thickened yet flexible sidewall on at least one of the sidewalls of the present heavy-duty use tire achieves substantial reduction in the cutting and damage of the tire&#39;s outer sidewall during use, and also helps greatly protect the tire&#39;s carcass, so that it can advantageously be reused and retreaded several times. The relief area near the inner flange of the thickened sidewall prevents unwanted cutting and damage to the thickened sidewall by the associated metal rim flange edge.  
      From the foregoing, it is believed that those skilled in the art will readily appreciate the unique features and advantages of the present invention over previous types and designs of heavy duty use pneumatic tires. Further, it is to be understood that while the present invention has been described in relation to a particular preferred embodiment as set forth in the accompanying drawings and as above described, the same nevertheless is susceptible to change, variation and substitution of equivalents without departure from the spirit and scope of this invention. It is therefore intended that the present invention be unrestricted by the foregoing description and drawings, except as may appear in the following appended claims.