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
  • B60C15/00—Tyre beads, e.g. ply turn-up or overlap
  • B60C15/06—Flipper strips, fillers, or chafing strips and reinforcing layers for the construction of the bead
• • 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
  • B60C3/00—Tyres characterised by the transverse section
  • B60C3/04—Tyres characterised by the transverse section characterised by the relative dimensions of the section, e.g. low profile
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
  • B60C9/02—Carcasses
  • B60C9/0292—Carcass ply curvature
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D30/00—Producing pneumatic or solid tyres or parts thereof
  • B29D30/06—Pneumatic tyres or parts thereof (e.g. produced by casting, moulding, compression moulding, injection moulding, centrifugal casting)
  • B29D30/48—Bead-rings or bead-cores; Treatment thereof prior to building the tyre
  • B29D2030/481—Fillers or apexes

Definitions

• This invention relates to a radial ply pneumatic tire having a predetermined ply cord path.
• Tire engineers have historically established the contours of tires by building a mold having a predetermined contour, placing green or unvulcanized tires with predetermined amounts of rubber on either side of the reinforcing plies into the mold, expanding the tire casing against the mold using an inflatable bladder and then applying heat and pressure to cure the tire.
• the mold is built with annular bead forming rings that form the contour of the bead portion 200 of the tire 100. These bead rings have a molding surface that generally approximates the contour of the rim upon which the tire 100 will fit.
• the ply 210 is anchored to the bead cores 200 and conventionally in prior art tires 100 has a working ply path between the bead core 200 and the belt packages 140.
• the bead core and the rim flange limits the amount of movement the ply cords 210 can take.
• At the upper portion of the tire circumferentially extending belt package limits the radial growth of the ply.
• the ply cords when tensioned take a contour that approximates a single radius of curvature R UP . This single radius of curvature R UP is commonly called the "neutral ply line. "
• This single radius contour can only be held to a point as shown in Fig. 1. If the contour defined by R UP is maintained further a very steep curve is achieved that is axially extending at a location well above the rim flange of a conventional truck tire rim.
• the ply path deviates from the neutral ply path, shear stresses develop that can generate heat and degrade the rolling resistance and durability of the tire.
• the tire of the present invention has a consistent ply path in the lower sidewall that has very low stresses.
• This lower ply path contour is controlled by a unique precured contoured apex that can minimize or even eliminate the use of a spline fit.
• a tire 10 for mounting on a rim of a vehicle has a tread portion 12, a belt package 14 radially inward of the tread 12, a pair of sidewall portions 16 each extending radially inward from a lateral edge 15 of the belt package 14, a pair of beads 22 each having an annular bead core 20 and positioned radially inward of a respective sidewall portion 16, at least one carcass ply 24 located radially inward of the belt package and extending from bead 22 to bead 22,
• the at least one carcass ply 24 has radially extending parallel cords 24A and a pair of turnup ends 26, one turnup end is wrapped about each bead core 20 and extends radially outwardly to an end point positioned radially outwardly of a flange 52 of the rim 50.
• the tire 10 has a pair of precured bead filler portions 40, one precured bead filler portion 40 being adjacent to a radially outer surface of a bead core 20.
• the tire 10 is characterized by each precured bead filler 40 having an axially inner curvature 42.
• the axially inner curvature 42 is defined by a convex surface 42 A and a concave surface 42B.
• the convex surface 42 A is radially outwardly extending from axially inwardly of the bead core 20 to an inflection location T, the location T being substantially at or radially inward of a radially outer surface of the rim flange 52.
• the concave curvature 42B extends from the inflection location T to a radially outer end 41 located at or below the radial location of a maximum section width of the tire 10.
• the axially inner surface curvatures 42A,42B establishes a ply cord path 24A of the carcass ply 24 when the tire 10 is normally inflated and unloaded.
• the ply path 24A extends from radially above the rim flange 52 to the lateral ends of the belt package.
• the ply path 24A has a radius of curvature (RUPL) between the belt lateral ends to the radial location H of the maximum section width and a second radius of curvature RL PL in the range of equal to or greater than R UPL , preferably 100 % to 200 % R UPL between the location
• RUPL radius of curvature
• the inflection location T can be at a point or may include a short spline having a midpoint below the rim flange.
• Aspect ratio of the tire means the ratio of its section height (SH) to its section width (SW);
• Axial and “axially” means 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;
• Belt reinforcing structure means at least two layers of plies of parallel cords, woven or unwoven, underlying the tread, unanchored to the bead, and having both left and right cord angles in the range from 17 degrees to 27 degrees with respect to the equatorial plane of the tire;
• Carcass means the tire structure apart from the belt structure, tread, under tread, 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;
• Chippers means a reinforcement structure located in the bead portion of the tire
• Core means one of the reinforcement strands of which the plies in the tire are comprised
• Design rim means a rim having a specified configuration and width.
• the design rim and design rim width are as specified by the industry standards in effect in the location in which the tire is made.
• the design rims are as specified by the Tire and Rim Association.
• the rims are as specified in the European Tyre and Rim Technical Organization - Standards Manual and the term design rim means the same as the standard measurement rims.
• the standard organization is The Japan Automobile Tire Manufacturer's Association.
• Equatorial plane (EP) means the plane perpendicular to the tire's axis of rotation and passing through the center of its tread
• 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;
• Normal rim diameter means the average diameter of the rim flange at the location where the bead portion of the tire seats
• Normal inflation pressure refers to the specific design inflation pressure and load assigned by the appropriate standards organization for the service condition for the tire
• Normal load refers to the specific design inflation pressure and load assigned by the appropriate standards organization for the service condition for the tire;
• Ply means a continuous layer of rubber-coated parallel cords;
• Ring and radially means directions radially toward or away from the axis of rotation of the tire;
• Ring-ply tire means belted or circumferentially-restricted pneumatic tire in which the ply cords which extend from the bead to bead are laid at cord angles between 65 degrees and 90 degrees with respect to the equatorial plane of the tire;
• Section height means the radial distance from the nominal rim diameter to the outer diameter of the tire at its equatorial plane
• SW Siliconection width
• Measurement width means the maximum linear distance parallel to the axis of the tire and between the exterior of its sidewalls when and after it has been inflated at normal pressure for 24 hours, but unloaded, excluding elevations of the sidewalls due to labeling, decoration or protective bands.
• Fig. 1 is a schematic view of half of a cross section of a tire and its resultant geometry as discussed herein.
• Fig. 2 is an enlarged schematic view of the lower bead portion of the tire of Fig. 1 and its resultant geometry.
• Fig. 3 is a cross sectional view of half of a prior art tire.
• Fig. 4 is a cross sectional view of a neutral contour ply line in a theoretical tire as described by Purdy.
• Fig. 5 is a cross section of a bead portion of a theoretical tire as disclosed by Purdy.
• Fig. 6 is a cross sectional view of one-half of a tire made in accordance to the invention.
• Fig. 7 is a cross sectional view of one-half of a second embodiment tire made in accordance to the invention.
• Figs. 8 A and 8B are enlarged views of the cross sections of the precured apex bead core assemblies according to the invention.
• Figs. 1 and 2 disclose abbreviations or initials that facilitate the understanding, the initials being similarly referred to in the text that follows. For a given tire 10 of a particular size, it is assumed at the outset that mold (OD), section diameter (SD) and molded base width (MBW) are known.
• tread width, tread radius and belt width have been determined from methods in standard practice. There are several methods to determine TAW. One such method is to use molded base width +/- 5 %. Once the TAW is determined, the tread radius may be determined from the following construction: An angled line is drawn at -5 degrees through the mold OD point.
• Five input parameters are needed to specify a neutral contour ply line. These parameters are RC, YM, RB, YB, and PR (shown in Fig. 1). The parameters are sufficient to define a well known mathematical curve from point YS to point (RB,YB).
• N sin ⁇ sin ⁇ and several terms of the equation were also defined.
• N be the total number of cords in the v plies of a tire and p be the inflation pressure.
• the bead position In order to determine the RB,YB point the bead position must be established.
• the lateral position of the bead bundle is determined by first offsetting the upper portion of the mold ring in-board and parallel an amount BMG (equal to the sum of the gages of the gum chafer, fabric chafer, chipper, ply and flipper).
• BMG equal to the sum of the gages of the gum chafer, fabric chafer, chipper, ply and flipper.
• the lower right-hand vertex of the bead wire bundle is then positioned axially on this line.
• the upper portion of the mold ring is offset outboard and parallel 0.5". From the intersection of the mold sharp diameter line and this offset line, a line is drawn at 135 degrees to the horizontal. A vertical line is drawn through the center of the bead bundle. The intersection of the vertical line and the 135 degree line is the RB,YB point.
• a neutral contour line may now be constructed with an estimate of the PR such, that the YS point (edge of the constant radius PR) falls between 80-85 % of dimension WBA, where WBA is the width of the belt covering the "wedge" . Further estimates of PR may be used in an iterative fashion until the target YS is attained. REVISING THE UPPER PLY CONTOUR ONE
• the lower ply line is revised in the following manner:
• a point X (see Fig. 2) on the mold surface is located at the intersection of the heel radius and the mold ring ledge.
• the ply ending 26 lies on a circular arc of radius PEH
• Point E is then established on the inboard side of the ply ending 26 and a circle of radius Tl is then drawn to establish the distance to the ply 24 (see note 3). Note that at this point the appropriate ply gage and flipper gages have been laid in on the inboard side of the bead as concentric circular arcs.
• a spline 70 is then drawn through the YM point (point A), tangent to the circle centered at E (point B), and tangent to the ply circle (point D) on the inboard side of the bead (dashed line).
• a precured contoured apex 40 provides a surface 42 that maintain its profile during the vulcanization process.
• the contour 42 By profiling the contour 42 of a precured apex 40 with a convex surface 42A axially inward of the bead core 20 and extending to a radial location T, location T being at or below radial height Z of the rim flange 52 of the design rim 50 that the tire 10 is to be mounted to, the contour 42 has an inflection point or short spline line at T wherein the axially inner surface becomes concave 42B, the concave surface 42B extending from the inflection point T to the radially outer end 41 of the apex 40, the radially outer end 41 being at or preferably slightly below the radial location H of the maximum section width SW of the tire 10.
• the spline T When T is constructed as a short spline one preferred approximation of the spline T is established as a line tangent to the circular arc established by the RL PL radius and tangent to the circular arc adjacent the bead core 20.
• the average length of the spline T must be at of below the radial location Z of the rim flange Z. This insures that although a spline is used it must be very short in length and thus limits the amount of deviation from the optimal neutral contour line. From a geometric fit relationship as the LPL/ ⁇ UPL rau0 increases greater than 1.0, then the length of the spline T decreases to a point wherein the tangency of the circular arcs is a point T. Importantly, the location T, whether a point or the midpoint of the spline, must lie below the rim flange 52.
• the ply cord's lower path 24 below the maximum section width is dictated by the overall contour of the precured apex 40.
• the ply hne 24A in the upper shoulder region has a single radius of curvature R UPL , R UPL extending from below the belt 14 near the belt edges 15 to the maximum section width SW at the section width diameter SD. Near that location the curvature of the ply line transitions to a second lower radius of curvature R LP , R LPL, s greater than or equal to R UP , preferably about 100% to 250% the radius R UPL , more preferably about 125 % to 200% R UPL .
• Fig. 8 A and 8B assuming one draws a line S tangent to the convex surface 42A of the precured apex 42 at an angle of 45° relative to the radial direction and then extends that line to intersection point S 1 on the axially inner concave surface 42B, the extension of line S will cover or extend between 50% and 100% of the precured apex 40 length lying below the intersection point S 1 .
• the maximum distance X 1 between T and the S 1 between the line S and the ply line path 24 will be at least 1.0, preferably at least 2 times the thickness of the ply gauge
• the resultant tire 10 exhibits an approximately neutral contour to a radial location at or below the rim flange 52. This greatly reduces the shear stress of the cords and gives the tire 10 superior performance improvements.
• the precured apex 40 is believed most efficiently manufactured using injection molding however, compression molding of the apex can also achieve similar benefits as described above.
• precured apex means that rubber flow associated with the vulcanization process cannot appreciably occur.
• precured can also encompass partially cured rubber apex as long as the contour profile 42 can be maintained to provide the ply line 24A shape.
• bead core 20 should be inserted into the apex forming mold to make a bead and precured apex assembly 43. This is naturally a method that further insures uniformity of these parts during tire assembly.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Tires In General (AREA)
• Non-Portable Lighting Devices Or Systems Thereof (AREA)
• Paper (AREA)

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Cited By (2)

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Citations (6)

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• 1997
  • 1997-04-03 AT AT97917842T patent/ATE219730T1/de not_active IP Right Cessation
  • 1997-04-03 EP EP97917842A patent/EP1028859B1/en not_active Expired - Lifetime
  • 1997-04-03 AU AU26065/97A patent/AU2606597A/en not_active Abandoned
  • 1997-04-03 JP JP54158798A patent/JP4056089B2/ja not_active Expired - Fee Related
  • 1997-04-03 CA CA002284598A patent/CA2284598A1/en not_active Abandoned
  • 1997-04-03 DE DE69713631T patent/DE69713631T2/de not_active Expired - Fee Related
  • 1997-04-03 KR KR1019997008957A patent/KR20010005881A/ko not_active Withdrawn
  • 1997-04-03 WO PCT/US1997/005542 patent/WO1998043836A1/en not_active Ceased
• 1998
  • 1998-03-24 ZA ZA982488A patent/ZA982488B/xx unknown

Patent Citations (6)

Non-Patent Citations (1)

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