JP4393653B2 - Pneumatic radial tire - Google Patents

Description

試験の結果、ビード部に補強層の設けられていない比較例１のタイヤはビードアンシーティング抵抗値が基準以下であるため使用できず、ビード部に補強層の設けられた実施例のタイヤはビードアンシーティング抵抗値が基準を満足しており、ビード部を確実にリムに保持可能であることが分かる。
【０１３０】
【発明の効果】
以上説明したように、本発明の空気入りラジアルタイヤは上記の構成としたので、軽量化及び高速耐久性を維持しつつビードアンシーティング抵抗を増大させることができる、という優れた効果を有する。
【図面の簡単な説明】
【図１】 本発明の第１の実施形態に係る空気入りラジアルタイヤの断面図である。
【図２】 図１に示す空気入りラジアルタイヤのベルト層の平面図である。
【図３】 本発明の第２の実施形態に係る空気入りラジアルタイヤの断面図である。
【図４】 本発明の第３の実施形態に係る空気入りラジアルタイヤの断面図である。
【図５】 本発明の第４の実施形態に係る空気入りラジアルタイヤの断面図である。
【図６】 本発明の第５の実施形態に係る空気入りラジアルタイヤのベルトの断面図である。
【図７】 本発明の第６の実施形態に係る空気入りラジアルタイヤのベルトの断面図である。
【図８】 （Ａ）及び（Ｂ）は、ゴムの弾性率を測定する方法を説明する説明図である。
【符号の説明】
１０ 空気入りラジアルタイヤ
１１ ビード部
１２ ビードコア
１４ カーカス
１６ トレッド部
１９ スチールコード（コード）
２０Ａ 傾斜ベルト層
２０Ｂ 周方向ベルト層
２１ 有機繊維コード（コード）
２２ 補強層
４０ タイヤ幅方向端部
４２ タイヤ幅方向中央部
Ｐ タイヤ最大幅位置[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a pneumatic tire, and more particularly to a pneumatic radial tire excellent in cornering properties and excellent in high-speed durability, and more particularly to a pneumatic radial tire suitable for a passenger car mainly for weight reduction.
[0002]
[Prior art]
  Now that energy saving has been screamed, in automobiles, studies to improve fuel efficiency by reducing weight have been conducted, and with this, the demand for weight reduction of tires also increases year by year. This tendency is remarkable, especially in general-purpose pneumatic radial tires for passenger cars.
[0003]
  Therefore, a pneumatic radial tire consisting of a slant belt including a plurality of steel cords inclined with respect to the tire equatorial plane and a circumferential belt including a plurality of organic fiber cords or steel cords parallel to the tire equatorial plane is proposed. (For example, JP-A-8-318706).
[0004]
[Problems to be solved by the invention]
  In the pneumatic radial tire described in Japanese Patent Laid-Open No. 8-318706, the belt has two layers, and the weight is reduced by using a high-strength organic fiber cord (or an optimally arranged steel cord) for the circumferential belt. Improvement of high-speed durability is achieved.
[0005]
  However, as described above, a belt having a structure in which a plurality of cords parallel to the tire equatorial plane and a plurality of cords inclined with respect to the tire equatorial plane are stacked has an advantage of being lightweight, The structure of at least two inclined belts (so-called cross belt structure), the rigidity of the belt portion in the tire width direction is reduced, and the tread surface is shrunk in the tire width direction particularly when a large lateral force is generated. There is a problem that the amount of deformation increases.
[0006]
  Specifically, the cross-sectional shape of the tread has changed from a rectangular shape before deformation to a trapezoidal shape with a short upper side (tread surface side) at the time of deformation. The sheeting resistance decreased.)
[0007]
  An object of the present invention is to provide a pneumatic radial tire capable of increasing bead unseating resistance while maintaining weight reduction and high-speed durability in consideration of the above facts.
[0008]
[Means for Solving the Problems]
  According to the first aspect of the present invention, a plurality of cords or filaments extending at an inclination with respect to the tire equatorial plane are arranged on the outer periphery of a crown portion of a carcass having a toroid shape straddling between at least a pair of bead cores. An inclined belt layer of at least one layer, at least one circumferential belt layer arranged on the inclined belt layer, in which a plurality of cords are arranged substantially parallel to the tire equatorial plane, and the tire of the circumferential belt layer In a pneumatic radial tire provided with a tread provided radially outward, the bead portion includesThe outer end in the radial direction is made of a metal fiber layer located on the outer side in the radial direction from the folded end of the carcassA reinforcing layer is provided.
[0009]
  Next, the operation of the pneumatic radial tire according to claim 1 will be described.
[0010]
  In the pneumatic radial tire according to claim 1, the in-plane bending rigidity of the tread is obtained by a single inclined belt layer in which a plurality of cords or filaments extending obliquely with respect to the tire equatorial plane is arranged. Can withstand lateral force of.
[0011]
  In addition, the circumferential belt layer of at least one layer in which a plurality of cords are arranged substantially in parallel with the tire equator plane provides the circumferential rigidity of the tread, can maintain the internal pressure, and has high high-speed durability. can get.
[0012]
  Furthermore, in the belt having a structure in which a plurality of cords parallel to the tire equator plane and a plurality of cords inclined with respect to the tire equator plane are stacked, the tire of the belt portion is compared with the structure of the conventional cross belt structure. Since the rigidity in the width direction is reduced, the deformation of the tread is increased when a large lateral force is generated, which causes a decrease in the bead unseating resistance of the tire, but the pneumatic radial tire of the present invention Then, since the reinforcement layer is provided in the bead portion, the lateral rigidity of the tire side portion is increased, the bead unseating resistance is increased, and the bead portion can be reliably held on the rim even when a large lateral force is applied. it can.
[0013]
[0014]
[0015]
  Claim 1In the pneumatic radial tire, the outer end in the radial direction of the reinforcing layer is positioned radially outward from the folded end portion of the carcass, so that the lateral rigidity of the tire side portion can be further increased, and the bead unseat resistance is increased. Can be increased.
  Since the reinforcing layer on which the compressive force acts needs to resist compressive deformation, it is preferably a metal fiber.
[0016]
  Claim 2The invention ofClaim 1In the pneumatic radial tire, the reinforcing layer is adjacent to the folded portion of the carcass.
[0017]
  next,Claim 2The operation of the pneumatic radial tire will be described.
[0018]
  The force that tries to shift the bead part from the rim (the force that tries to remove it) is the force that goes from the outside in the tire axial direction to the inside, and when this force acts on the bead part, the bead part bends (bends that dent inside the tire). ) Resist.
[0019]
  At this time, a compressive force acts on the folded portion of the carcass, but the reinforcing layer adjacent to the folded portion acts so as to suppress deformation due to the compressive force, thereby further increasing the bead unseating resistance.
[0020]
  Claim 3The invention ofClaim 2In the pneumatic radial tire, the reinforcing layer is located on a tire outer surface side of the folded portion of the carcass.
[0021]
  next,Claim 3The operation of the pneumatic radial tire will be described.
[0022]
  Claim 3In a pneumatic radial tire, the reinforcing layer is located on the outer surface side of the carcass folding portion, so when the bead portion is bent, the reinforcing layer is interposed on the innermost side of the bend, and more effectively compresses by bending. I will resist it.
[0023]
[0024]
[0025]
[0026]
  Claim 4The pneumatic radial tire according to claim 1 or 2, wherein the reinforcing layer is adjacent to a main body portion of the carcass.
[0027]
  next,Claim 4The operation of the pneumatic radial tire will be described.
[0028]
  The force that tries to shift the bead part from the rim (the force that tries to remove it) is the force that goes from the outside in the tire axial direction to the inside, and when this force acts on the bead part, the bead part bends (bends that dent inside the tire). ) Resist.
[0029]
  At this time, a tensile force acts on the main body portion of the carcass, but the reinforcing layer adjacent to the main body portion acts so as to suppress deformation due to the tensile force, thereby further increasing the bead unseating resistance.
[0030]
[0031]
[0032]
[0033]
[0034]
  Claim 5The invention ofThe method according to any one of claims 1 to 4.In the pneumatic radial tire, the cord of the circumferential belt layer is made of polyethylene terephthalate fiber or nylon fiber, has a double twisted structure, and the total denier number DT is in the range of 1000d to 6000d. Is T (number of times / 10 cm) and specific gravity is ρ, the twist coefficient Nt is Nt = T × (0.139 × DT / 2 × 1 / ρ)^1/2× 10^-3It is characterized by being in the range of ≦ 0.3.
[0035]
  next,Claim 5The operation of the pneumatic radial tire will be described.
[0036]
  When the cord of the circumferential belt layer is polyethylene terephthalate fiber or nylon fiber, and the twist coefficient Nt of this cord is 0.3 or less, sufficient cornering performance can be obtained.
[0037]
  The reason why the cord of the circumferential belt layer has a double twisted structure is from the viewpoint of improvement in compression fatigue property and workability of the cord itself, and the total denier number DT is in the range of 1000d to 6000d. If it is less than that, it is difficult to physically code. On the other hand, if it exceeds 6000d, the cord becomes too thick, and the amount of rubber must be increased along with it, resulting in an increase in tire weight.
[0038]
  Moreover, if the twist coefficient Nt is too small, the cord may be scattered and workability may be deteriorated.Because there is, 0.1 or more is preferable.
[0039]
  Further, by using polyethylene terephthalate fiber or nylon fiber for the cord of the circumferential belt layer, cord breakage due to compression fatigue is less likely to occur compared to the conventionally used aramid fiber cord having a twist coefficient Nt of 0.3 or less. .
[0040]
  Here, the double twist structure is a structure in which one or more yarns are aligned and twisted (bottom twist), and two or more yarns are aligned and twisted in the opposite direction to the lower twist (upper twist). Say.
[0041]
  The total denier number DT means the product of the raw yarn denier and the number of twists.
[0042]
  Claim 6The invention ofThe method according to any one of claims 1 to 4.In the pneumatic radial tire, the cord of the circumferential belt layer is made of polyethylene naphthalate fiber, has a double twisted structure, and the total denier number DT is in the range of 1000d to 6000d. (Number of times / 10 cm) When the specific gravity is ρ, the twist coefficient Nt is Nt = T × (0.139 × DT / 2 × 1 / ρ)^1/2× 10^-3It is characterized by being in the range of ≦ 0.6.
[0043]
  next,Claim 6The operation of the pneumatic radial tire will be described.
[0044]
  When the cord of the circumferential belt layer is made of polyethylene naphthalate fiber and the twist coefficient Nt of the cord is 0.6 or less, sufficient cornering performance can be obtained.
[0045]
  The reason why the cord of the circumferential belt layer has a double twisted structure is from the viewpoint of improvement in compression fatigue property and workability of the cord itself, and the total denier number DT is in the range of 1000d to 6000d. If it is less than that, it is difficult to physically code. On the other hand, if it exceeds 6000d, the cord becomes too thick, and the amount of rubber must be increased along with it, resulting in an increase in tire weight.
[0046]
  Moreover, if the twist coefficient Nt is too small, the cord may be scattered and workability may be deteriorated.Because there is, 0.1 or more is preferable.
[0047]
  Further, by using polyethylene naphthalate fiber for the cord of the circumferential belt layer, cord breakage due to compression fatigue is less likely to occur as compared with conventionally used aromatic polyamide fiber cords.
[0048]
  Claim 7The invention ofThe method according to any one of claims 1 to 4.In the pneumatic radial tire, the cord of the circumferential belt layer is made of vinylon fiber, has a double twisted structure, and the total denier number DT is in the range of 1000d to 6000d. / 10 cm) and the specific gravity is ρ, the twist coefficient Nt is Nt = T × (0.139 × DT / 2 × 1 / ρ)^1/2× 10^-3It is characterized by being in the range of ≦ 0.6.
[0049]
  next,Claim 7The operation of the pneumatic radial tire will be described.
[0050]
  When the cord of the circumferential belt layer is made of vinylon fiber and the twist coefficient Nt of the cord is 0.6 or less, sufficient cornering performance can be obtained.
[0051]
  The reason why the cord of the circumferential belt layer has a double twisted structure is from the viewpoint of improvement in compression fatigue property and workability of the cord itself, and the total denier number DT is in the range of 1000d to 6000d. If it is less than that, it is difficult to physically code. On the other hand, if it exceeds 6000d, the cord becomes too thick, and the amount of rubber must be increased along with it, resulting in an increase in tire weight.
[0052]
  Moreover, if the twist coefficient Nt is too small, the cord may be scattered and workability may be deteriorated.Because there is, 0.1 or more is preferable.
[0053]
  Further, by using vinylon fibers for the cords in the circumferential belt layer, cord breakage due to compression fatigue is less likely to occur as compared to the conventionally used aramid fiber cords having a twist coefficient Nt of 0.3 or less.
[0054]
  Claim 8The invention ofThe method according to any one of claims 1 to 4.In the pneumatic radial tire of No. 1, the cord of the circumferential belt layer is made of aramid fiber, has a double twist structure, and the total denier number DT is in the range of 1000d to 6000d. / 10 cm) and the specific gravity is ρ, the twist coefficient Nt is Nt = T × (0.139 × DT / 2 × 1 / ρ)^1/2× 10^-3It is characterized by being in the range of ≧ 0.3.
[0055]
  When the cord of the circumferential belt layer is an aramid fiber and the twist coefficient Nt of the cord is 0.3 or more, good cord breakage resistance is obtained.
[0056]
  The reason why the cord of the circumferential belt layer has a double twisted structure is from the viewpoint of improvement in compression fatigue property and workability of the cord itself, and the total denier number DT is in the range of 1000d to 6000d. If it is less than that, it is difficult to physically code. On the other hand, if it exceeds 6000d, the cord becomes too thick, and the amount of rubber must be increased along with it, resulting in an increase in tire weight.
[0057]
  Claim 9The invention ofThe method according to any one of claims 1 to 8.Tangent loss tan δ of the cord of the circumferential belt layer is 0.3 or less under the conditions of an initial tension of 1 kgf / strand, a strain amplitude of 0.1%, a frequency of 20 Hz, and an ambient temperature of 25 ° C. It is characterized by being.
[0058]
  next,Claim 9The operation of the pneumatic radial tire will be described.
[0059]
  Since PET, nylon, PEN, vinylon, and aramid fibers have a large work loss and are likely to generate heat, these fiber cords may melt in a high-speed durability test. Therefore, by setting the tangent loss tan δ of the cord of the circumferential belt layer to 0.3 or less under the conditions of an initial tension of 1 kgf / strand, a strain amplitude of 0.1%, a frequency of 20 Hz, and an ambient temperature of 25 ° C. Melting of these fiber cords can be prevented.
[0060]
  Claim 10The invention ofAny one of Claims 1-4In the pneumatic radial tire according to claim 1, the cord of the circumferential belt layer has an elastic modulus of 3000 kgf / mm.² It is characterized by the above steel cord.
[0061]
  next,Claim 10The operation of the pneumatic radial tire will be described.
[0062]
  When steel cord is used for the cord of the circumferential belt layer, the elastic modulus is 3000kgf / mm² Although the tire weight is somewhat increased as compared with the case where the above-described organic fiber cords such as PET and nylon are used for the circumferential belt, the circumferential rigidity can be further increased, and sufficient Cornering power can be obtained.
[0063]
  The elastic modulus is 3000 kgf / mm² If it is less than this, the rigidity cannot be improved more effectively.
[0064]
  Further, the number of steel cords to be driven is preferably in the range of 15 to 50 per 50 mm from the viewpoint of securing circumferential rigidity and reducing the weight.
[0065]
  Claim 11The invention ofThe method according to any one of claims 1 to 10.The elastic modulus of the rubber covering the circumferential belt layer is 200 kgf / mm.² It is characterized by the above.
[0066]
  As shown in FIG. 8 (A), the elastic modulus of the coated rubber is a rubber test piece in a cavity of a steel jig 100 having a cylindrical cavity having a diameter d of 14 mm and a height h of 28 mm. After filling 102 with no gap, this jig 100 is set on a compression tester 104 as shown in FIG. The amount of displacement at this time is measured by the laser displacement meter 106 and calculated from the relationship between the load and the displacement.
[0067]
  next,Claim 11The operation of the pneumatic radial tire will be described.
[0068]
  If the elastic modulus of the rubber covering the circumferential belt layer is too low, the cord willIt becomes easy to moveThe local buckling of the cord is likely to occur, and the cord may be broken. Therefore, the elastic modulus of the rubber covering the circumferential belt layer is 200 kgf / mm.² By setting it as the above, it can be made hard to produce a code piece.
[0069]
  Claim 12The invention ofThe method according to any one of claims 1 to 11.In the pneumatic radial tire, the cord of the circumferential belt layer is wound spirally.
[0070]
  next,Claim 12The operation of the pneumatic radial tire will be described.
[0071]
  Claim 12In the pneumatic radial tire, the cord of the circumferential belt layer is spirally wound, so that the uniformity of the tire can be improved.
[0072]
  Claim 13The invention ofThe method according to any one of claims 1 to 12.In the pneumatic radial tire, the cords or filaments of the inclined belt layer are made of a steel material.
[0073]
  next,Claim 13The operation of the pneumatic radial tire will be described.
[0074]
  By using a steel material for the cords or filaments of the inclined belt, sufficient tire strength can be obtained.
[0075]
  Claim 14The invention ofThe method according to any one of claims 1 to 13.In the pneumatic radial tire, the cords or filaments of the inclined belt layer are characterized in that the inclination angle with respect to the tire equatorial plane is in the range of 15 ° to 45 °.
[0076]
  next,Claim 14The operation of the pneumatic radial tire will be described.
[0077]
  By setting the inclination angle of the cord or filament of the inclined belt layer to the tire equatorial plane in the range of 15 ° to 45 °, sufficient in-plane shear rigidity can be obtained in the tread.
[0078]
  Claim 15The invention ofThe method according to any one of claims 1 to 14.In the pneumatic radial tire, the thickness of the rubber positioned between the cord or filament of the inclined belt layer and the cord of the circumferential belt layer on the innermost side in the tire radial direction is defined as the end in the tire width direction in the tire width direction cross section. This is characterized in that the portion is larger than the central portion in the tire width direction.
[0079]
  next,Claim 15The operation of the pneumatic radial tire will be described.
[0080]
  The thickness of the rubber located between the cord or filament of the inclined belt layer and the cord of the circumferential belt layer on the innermost side in the tire radial direction is the center in the tire width direction at the tire width direction end in the tire width direction cross section. The thickness of the rubber at the end in the tire width direction is more than twice the thickness of the rubber at the center in the tire width direction. The range of maintaining the thickness of the rubber at the center in the direction is 50 to 90% of the width of the inclined belt layer centering on the tire equator plane, so-called sandwich beam effect (TWChou and FKKO , "" Textile Structural Composite "" described in Elseveir (1989)), and as a result, the bending stiffness in the tire circumferential direction is relatively lower at the center in the tire width direction than at both ends in the tire width direction. , Tire ground contact length is It is longer in the center area and shorter in both shoulder areas, making it possible to bring the tire's ground contact shape closer to a rounded shape with a rounded corner. Can be eliminated quickly, and the occurrence of hydroplaning can be suppressed.
[0081]
  Claim 16The invention ofThe method according to any one of claims 1 to 15.In the pneumatic radial tire, the thickness of the covering rubber located between the cord on the outermost circumferential belt layer in the tire radial direction and the inner peripheral surface of the tread rubber is determined in the tire width direction in the tire width direction cross section. Larger than the end in the tire width direction at the centerThatIt is a feature.
[0082]
  next,Claim 16The operation of the pneumatic radial tire will be described.
[0083]
  As the sum of the thickness of the inclined belt layer and the thickness of the circumferential belt layer becomes smaller at the center portion in the tire width direction, irregularities corresponding to the cord appear near the center portion in the tire width direction of the tire inner surface after vulcanization. When the phenomenon (cord out phenomenon) occurs, the thickness of the covering rubber positioned between the cord of the circumferential belt on the outermost radial side of the tire and the inner peripheral surface of the tread rubber is set at the tire width direction central portion. By making it larger than the end in the width direction, the sum of the thickness of the inclined belt layer and the thickness of the circumferential belt layer can be made uniform over the tire width direction, and the cording phenomenon can be suppressed. .
[0084]
  Claim 17The invention ofThe method according to any one of claims 1 to 16.In the pneumatic radial tire, the circumferential belt layer has at least two layers in the center portion in the tire width direction.
[0085]
  next,Claim 17The operation of the pneumatic radial tire will be described.
[0086]
  When it is necessary to further suppress the protrusion in the center portion in the tire width direction during high-speed running, it is preferable that the circumferential belt layer is at least two layers in the center portion in the tire width direction. Although a relatively wide circumferential belt layer may be disposed, a wide circumferential belt layer covering almost the entire surface of the inclined belt layer, and a narrow circumferential belt layer covering only the central portion of the wide circumferential belt layer, The circumferential belt layer may be configured by.
[0087]
  Claim 18.The invention ofThe method according to any one of claims 1 to 17.In the pneumatic radial tire, the circumferential belt layer has at least two layers at the end in the tire width direction.
[0088]
  next,Claim 18.The operation of the pneumatic radial tire will be described.
[0089]
  When it is necessary to further suppress the belt end separation, the circumferential belt layer is preferably at least two layers at the tire width direction end, and in this case as well, two or more wide circumferential belt layers are used. The entire surface of the inclined belt layer may be covered with, but the wide circumferential belt layer covering almost the entire surface of the inclined belt layer and both ends of the wide circumferential belt layer, or both both end portions and the central portion are covered. You may comprise with a narrow circumferential belt layer. As described above, the width, the number of layers, and the like of the circumferential belt layer can be appropriately changed as necessary.
[0090]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
  Next, a first embodiment of a pneumatic radial tire of the present invention will be described with reference to the drawings.
[0091]
  As shown in FIG. 1, a pneumatic radial tire 10 includes a carcass 14 that is folded and locked around a bead core 12 embedded in a bead portion 11 from the inside to the outside of the tire, and a main body portion 14A and a winding portion 14B of the carcass 14. A bead filler 15 disposed between the tread portion 16, a tread portion 16 located in the crown portion of the carcass 14, a sidewall portion 18 located in the side portion of the carcass 14, and two layers disposed inside the tread portion 16. The belt layer 20 is provided.
[0092]
  The carcass 14 has fiber cords arranged in a direction substantially perpendicular to the circumferential direction, and in the present embodiment, is constituted by a single carcass ply.
[0093]
  Further, the end portion of the winding portion 14B of the carcass 14 is located on the inner side in the tire radial direction from the maximum width position P of the carcass 14.
[0094]
  As shown in FIG. 2, the belt layer 20 is positioned on the inclined belt layer 20 </ b> A and a single inclined belt layer 20 </ b> A in which a plurality of steel cords 19 extending in an inclined manner with respect to the tire equatorial plane CL are arranged. And a circumferential belt layer 20B in which a plurality of organic fiber cords 21 are arranged substantially parallel to the tire equatorial plane CL.
[0095]
  Note that both the steel cord 19 of the inclined belt layer 20A and the organic fiber cord 21 of the inclined belt layer 20A are coated with a coating rubber as usual.
[0096]
  Here, the inclination angle of the steel cord of the inclined belt layer 20A with respect to the tire equatorial plane CL is preferably in the range of 15 ° to 45 °.
[0097]
  Next, the circumferential belt layer 20 </ b> B is a narrow strip of rubberized rubber that includes the repetitive number of organic fiber cords 21 (or one in some cases), and the organic fiber cords 21 substantially extend in the tire circumferential direction. It is wound endlessly in a spiral shape (spiral shape) so as to be parallel (0 ° to 5 °).
[0098]
  The organic fiber cord of the circumferential belt layer 20B is preferably polyethylene terephthalate fiber (PET), nylon fiber, polyethylene naphthalate fiber (PEN; polyethylene-2,6-naphthalate fiber is preferable), vinylon fiber, aramid fiber, etc. A twisted structure is preferred, and the total denier number DT is preferably in the range of 1000d to 6000d.
[0099]
  In the case of polyethylene terephthalate fiber (PET) and nylon fiber, the twist coefficient Nt is 0.3 or less, in the case of polyethylene naphthalate fiber (PEN), the twist coefficient Nt is 0.6 or less, and in the case of vinylon fiber, the twist coefficient Nt. Is 0.6 or less, and in the case of an aramid fiber, the twist coefficient Nt is preferably 0.3 or more.
[0100]
  Furthermore, the tangent loss tan δ of the organic fiber cord of the circumferential belt layer 20B is 0.3 or less under the conditions of an initial tension of 1 kgf / strand, a strain amplitude of 0.1%, a frequency of 20 Hz, and an ambient temperature of 25 ° C. Is preferred.
[0101]
  The elastic modulus of the covering rubber of the circumferential belt layer 20B is 200 kgf / mm.² The above is preferable.
[0102]
  Although the number of layers of the circumferential belt layer 20B may be two or more, about 1-2 layers are preferable from the viewpoint of weight reduction.
[0103]
  In addition, instead of the organic fiber cord, a steel cord can be used for the circumferential belt layer 20B. In this case, the elastic modulus of the steel cord is 3000 kgf / mm² As described above, the twisted structure is preferably 1 × N or 1 + N.
[0104]
  The number of steel cords to be driven is preferably in the range of 15 to 50 per 50 mm.
[0105]
  Here, the bead portion 11 of the pneumatic radial tire 10 of the present embodiment is provided with a reinforcing layer 22 in order to suppress bending deformation of the bead portion 11.
[0106]
  The reinforcing layer 22 is disposed along the outer surface of the winding upper portion 14B, and the radially outer end thereof is located on the outer side in the tire radial direction than the end portion of the winding upper portion 14B.
[0107]
  The reinforcing layer 22 includes a plurality of fiber cords extending along the tire radial direction. The direction of the fiber cord may be the tire radial direction, or may be inclined with respect to the tire radial direction (note that the inclination angle with respect to the tire radial direction is preferably 75 degrees or less).
  In addition, the fiber cord in the case where the reinforcing layer 22 is arranged along the winding portion 14B is preferably a metal fiber cord that is resistant to compression. In this embodiment, a steel cord is used as the metal fiber cord.
[0108]
  In this embodiment, the number of steel cords to be driven is 40/50 mm, and the inclination angle of the steel cord is 68 degrees.
[0109]
  Further, as shown in FIG. 1, the tread portion 16 has a plurality of circumferential main grooves 24 extending along the tire circumferential direction, and in this embodiment, a total of four, two on each side of the tire equatorial plane CL. Is formed.
(Function)
  Next, the operation of the pneumatic radial tire 10 of this embodiment will be described.
[0110]
  In the pneumatic radial tire 10 of the present embodiment, the in-plane bending rigidity of the tread portion 16 is obtained by the inclined belt layer 20A in which a plurality of steel cords 19 extending inclining with respect to the tire equatorial plane CL are arranged, and during cornering Can withstand lateral force of.
[0111]
  Further, the circumferential belt layer 20B in which a plurality of organic fiber cords 21 are arranged substantially in parallel with the tire equatorial plane CL can provide the circumferential rigidity of the tread portion 16, can maintain the internal pressure, and has a high speed. Durability is obtained.
[0112]
  Further, the bead portion 11 includes a reinforcing layer 22 including a steel cord and having a radially outer end positioned radially outward from an end portion of the winding portion 14B, and is disposed along the outside of the winding portion 14B. The lateral rigidity of the tire side portion can be further increased, and the bead unseating resistance can be further increased.
[Second Embodiment]
  Next, a second embodiment of the pneumatic radial tire of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.
[0113]
  As shown in FIG. 3, in the pneumatic radial tire 10 of the present embodiment, the reinforcing layer 22 is disposed along the inside of the winding portion 14B.
[0114]
  The operational effects are the same as those in the first embodiment.
[Third Embodiment]
  Next, a third embodiment of the pneumatic radial tire of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same structure as embodiment mentioned above, and the description is abbreviate | omitted.
[0115]
  As shown in FIG. 4, in the present embodiment, the reinforcing layer 22 is disposed along the outside of the main body portion 14A.
[0116]
  When a force for moving the bead portion 11 away from the rim (a force for removing the bead portion 11) is applied, a tensile force is applied to the reinforcing layer 22 disposed along the main body portion 14A of the carcass 14.
[0117]
  In the present embodiment, the reinforcing layer 22 acts to suppress deformation due to the tensile force, and further increases the bead unseating resistance.
[0118]
  Therefore, when the reinforcing layer 22 is disposed along the main body portion 14A, the cord of the reinforcing layer 22 is highly elastic.Metal fibers are preferred.
[0119]
  The elastic modulus of the fiber is 200kgf / mm ² The above is preferable.
[Fourth Embodiment]
  Next, a fourth embodiment of the pneumatic radial tire of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same structure as embodiment mentioned above, and the description is abbreviate | omitted.
[0120]
  As shown in FIG. 5, in this embodiment, the reinforcing layer 22 is wound around the bead core 12 along the carcass 14.
[0121]
  In the present embodiment, since the reinforcing layer 22 has two layers of the main body portion 14A side and the winding portion 14B side, the rigidity of the bead portion 11 can be further increased.
[Fifth Embodiment]
  Next, a fifth embodiment of the pneumatic radial tire of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same structure as embodiment mentioned above, and the description is abbreviate | omitted.
[0122]
  As shown in FIG. 6, in this embodiment, the thickness t1 of the covering rubber positioned between the steel cord 19 of the inclined belt layer 20A and the organic fiber cord 21 of the circumferential belt layer 20B adjacent to the steel cord 19 is set to the tire. Within the cross section in the width direction, the end portion 40 in the tire width direction is set larger than the central portion 42 in the tire width direction.
[0123]
  The thickness t1 of the coated rubber located between the steel cord 19 and the organic fiber cord 21 at the tire width direction end portion 40 may be set to be twice or more than the thickness t1 at the tire width direction center portion 42. preferable.
[0124]
  Further, the range in which the thickness t1 of the covering rubber at the tire width direction center portion 42 is maintained is preferably set to a range of 50 to 90% of the width of the inclined belt layer 20A with the tire equatorial plane CL as the center.
[0125]
  By maintaining the thickness of the covering rubber positioned between the steel cord 19 and the organic fiber cord 21 at the tire width direction central portion 42 as described above, a so-called sandwich beam effect is produced, and as a result, the tire In the circumferential bending stiffness, the tire width direction central portion 42 is relatively lower than the tire width direction end portion 40.
[0126]
  For this reason, the tire ground contact length is longer in the tread central region and shorter in both shoulder regions, making it possible to bring the tire ground contact shape closer to a rounded shape with a reduced corner, and the water ahead of the tire traveling direction when running on a wet road surface. It can be quickly eliminated to the side of the tire and the occurrence of hydroplaning can be suppressed.
[Sixth Embodiment]
  Next, a sixth embodiment of the pneumatic radial tire of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same structure as embodiment mentioned above, and the description is abbreviate | omitted.
[0127]
  As shown in FIG. 7, in the present embodiment, the thickness (t2) of the covering rubber positioned between the organic fiber cord 21 of the circumferential belt layer 20B and the inner peripheral surface of the rubber of the tread portion 16 is set as the tire width. Within the cross section, the tire width direction central portion 42 is set larger than the tire width direction end portion 40, and the sum T of the thickness of the inclined belt layer 20A and the thickness of the circumferential belt layer 20B is set in the tire width direction. Therefore, it is possible to suppress the cording phenomenon that occurs in the vicinity of the central portion 42 in the tire width direction of the tire inner surface after vulcanization.
(Test example)
  In order to confirm the effect of the present invention, a comparative example tire without a reinforcing layer and a plurality of example tires (each of which has a tire size of 175 / 65R14) in which the positions of the reinforcing layer were changed were produced, and the bead unseat resistance value Was measured.
[0128]
  Here, the bead unseating resistance value is a value obtained in a bead unseating test of JIS standard. According to JIS standards, in the case of tires for passenger cars, the minimum bead unseating resistance value must be 8895N or more.
[0129]
[Table 1]

  As a result of the test, the tire of the comparative example 1 in which the reinforcement layer is not provided in the bead portion cannot be used because the bead unseating resistance value is below the standard, and the tire in the embodiment in which the reinforcement layer is provided in the bead portion is a bead. It can be seen that the unsheeting resistance value satisfies the standard, and the bead portion can be reliably held on the rim.
[0130]
【The invention's effect】
  As described above, since the pneumatic radial tire of the present invention has the above-described configuration, it has an excellent effect that the bead unseating resistance can be increased while maintaining the weight reduction and the high speed durability.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a pneumatic radial tire according to a first embodiment of the present invention.
FIG. 2 is a plan view of a belt layer of the pneumatic radial tire shown in FIG.
FIG. 3 is a cross-sectional view of a pneumatic radial tire according to a second embodiment of the present invention.
FIG. 4 is a cross-sectional view of a pneumatic radial tire according to a third embodiment of the present invention.
FIG. 5 is a sectional view of a pneumatic radial tire according to a fourth embodiment of the present invention.
FIG. 6 is a sectional view of a belt of a pneumatic radial tire according to a fifth embodiment of the present invention.
FIG. 7 is a sectional view of a belt of a pneumatic radial tire according to a sixth embodiment of the present invention.
FIGS. 8A and 8B are explanatory diagrams for explaining a method of measuring the elastic modulus of rubber. FIGS.
[Explanation of symbols]
        10 Pneumatic radial tire
        11 Bead section
        12 Beadcore
        14 Carcass
        16 tread
        19 Steel cord (Cord)
        20A inclined belt layer
        20B Circumferential belt layer
        21 Organic fiber cord (code)
        22 Reinforcing layer
        40 End of tire width direction
        42 Center of tire width direction
          P Tire maximum width position

Claims (18)

One inclined belt layer in which a plurality of cords or filaments extending obliquely with respect to the tire equatorial plane are arranged on the outer periphery of the crown portion of the carcass that forms a toroid shape straddling between at least a pair of bead cores, and the inclination At least one circumferential belt layer on the belt layer, in which a plurality of cords are arranged substantially parallel to the tire equatorial plane, and a tread provided on the outer side in the tire radial direction of the circumferential belt layer; In pneumatic radial tires with
The pneumatic radial tire according to claim 1 , wherein the bead portion is provided with a reinforcing layer made of a metal fiber layer having a radially outer end positioned radially outward of the folded end portion of the carcass . The pneumatic radial tire according to claim 1, wherein the reinforcing layer is adjacent to a folded portion of the carcass. The pneumatic radial tire according to claim 2, wherein the reinforcing layer is located on a tire outer surface side of a folded portion of the carcass. The pneumatic radial tire according to claim 1, wherein the reinforcing layer is adjacent to a main body portion of the carcass. The cord of the circumferential belt layer is made of polyethylene terephthalate fiber or nylon fiber, has a double twisted structure, and the total denier number DT is in the range of 1000d to 6000d. When the specific gravity is ρ, the twist coefficient Nt is
Nt = T × (0.139 × DT / 2 × 1 / ρ) ^1/2 × 10 ⁻³ ≦ 0.3
The pneumatic radial tire according to any one of claims 1 to 4, wherein the pneumatic radial tire is within a range. The cord of the circumferential belt layer is made of polyethylene naphthalate fiber, has a double twisted structure, and the total denier number DT is in the range of 1000d to 6000d. Is ρ, the twist coefficient Nt is
Nt = T × (0.139 × DT / 2 × 1 / ρ) ^1/2 × 10 ⁻³ ≦ 0.6
The pneumatic radial tire according to any one of claims 1 to 4, wherein the pneumatic radial tire is within a range. The cord of the circumferential belt layer is made of vinylon fiber, has a twin twist structure, and the total denier number DT is in the range of 1000d to 6000d. The cord has a twist number T (number of times / 10 cm) and a specific gravity ρ Then, the twist coefficient Nt is
Nt = T × (0.139 × DT / 2 × 1 / ρ) ^1/2 × 10 ⁻³ ≦ 0.6
The pneumatic radial tire according to any one of claims 1 to 4, wherein the pneumatic radial tire is within a range. The cord of the circumferential belt layer is made of aramid fiber, has a double twisted structure, and the total denier number DT is in the range of 1000d to 6000d. Then, the twist coefficient Nt is
Nt = T × (0.139 × DT / 2 × 1 / ρ) ^1/2 × 10 ⁻³ ≧ 0.3
The pneumatic radial tire according to any one of claims 1 to 4, wherein the pneumatic radial tire is within a range. Code loss tangent tanδ of the circumferential belt layer, which initial tension 1 kgf / present, strain amplitude of 0.1%, under the conditions of frequency 20 Hz, ambient temperature 25 ° C, characterized in that less than 0.3 according The pneumatic radial tire according to any one of claims 1 to 8 . The pneumatic radial tire according to any one of claims 1 to 4, wherein the cord of the circumferential belt layer is a steel cord having an elastic modulus of 3000 kgf / mm ² or more. The pneumatic radial tire according to any one of claims 1 to 10, wherein the elastic modulus of the covering rubber of the circumferential belt layer is 200 kgf / mm ² or more.   The pneumatic radial tire according to any one of claims 1 to 11, wherein the cord of the circumferential belt layer is wound spirally.   The pneumatic radial tire according to any one of claims 1 to 12, wherein the cord or the filament of the inclined belt layer is made of a steel material.   The pneumatic radial tire according to any one of claims 1 to 13, wherein the cord or filament of the inclined belt layer has an inclination angle with respect to the tire equatorial plane in a range of 15 ° to 45 °.   The thickness of the rubber located between the cord or filament of the inclined belt layer and the cord of the circumferential belt layer at the innermost side in the tire radial direction is the center in the tire width direction at the tire width direction end in the tire width direction cross section. The pneumatic radial tire according to any one of claims 1 to 14, wherein the pneumatic radial tire is larger than that of the pneumatic radial tire. The thickness of the covering rubber located between the cord of the circumferential belt layer on the outermost side in the tire radial direction and the inner circumferential surface of the tread rubber is the end in the tire width direction at the center in the tire width direction in the cross section of the tire width direction. The pneumatic radial tire according to any one of claims 1 to 15, wherein the pneumatic radial tire is larger than a portion. The pneumatic radial tire according to any one of claims 1 to 16, wherein the circumferential belt layer is at least two layers in a central portion in the tire width direction. The pneumatic radial tire according to any one of claims 1 to 17, wherein the circumferential belt layer is at least two layers at an end in the tire width direction.

Images