JP2011235785A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve uneven-wear resistance on the outside in a tire width direction of a tread part by uniformizing radial growth from the center in the tire width direction of the tread part to the outside in the tire width direction.SOLUTION: This pneumatic tire 1 includes: at least two layers of cross belts 5A including cords each having an angle of 10-30° with respect to the tire circumferential direction, and laminated on the outside in the tire radial direction of a carcass 4 so that the cords intersect each other; and at least one layer of circumferential reinforcing layer 6 including cords 6a each having an angle of 0-5° with respect to the tire circumferential direction, and laminated on both sides in the tire width direction of the cross belt 5A by being divided in the tire width direction. The pneumatic tire also includes a rubber layer 7 arranged between the cross belts 5A at the center in the tire width direction.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can suppress uneven wear of a tread shoulder.

  The tires for trucks and buses with a low flatness ratio of 70% or less are provided with a circumferential reinforcing layer composed of cables and cords parallel to the tire circumferential direction for the purpose of improving durability and uneven wear resistance. is there.

  For example, a pneumatic tire (radial tire) described in Patent Document 1 includes a radial carcass, a tread band overlaid on the radial carcass in the crown portion of the radial carcass, and an annular shape inserted between the radial carcass and the tread band. A reinforcing structure, the annular reinforcing structure is composed of at least two radially overlapping metal cord layers having substantially the same width as the tread, and the metal cords are parallel in the layers but the other layers The metal cord intersects with the metal cord, and the metal cord of each layer is inclined at an angle of 10 [°] to 30 [°] relative to the longitudinal direction of the tire. In the pneumatic tire described in Patent Document 1, the annular reinforcing structure has an elongation of 4 [%] to 8 [%] at the breaking point on the outer side in the radial direction with respect to the layer in the side portion. And an annular reinforcing strip (circumferential reinforcing layer) with a long-strand metal cord positioned parallel to the tire equatorial plane, the reinforcing strip overlapping at least two radial cords of the metal cord The outer edge of the reinforcing strip coincides with the edge of the radially inner layer, and the axial width of the reinforcing strip is 7% to 40% of the axial width of the annular reinforcing structure. It has become.

Further, for example, a pneumatic tire described in Patent Document 2 (a tire having an aspect ratio H / S of 0.6 or less) has at least two working belt plies made of a non-extensible cable, form an angle of 10 [°] to 45 [°] with respect to the circumferential direction intersect each other, said ply having a belt having a width equal to at least 80 [%] of the maximum axial width S ₀ of the carcass. The pneumatic tire described in Patent Document 2 firstly forms a non-elongation that forms an axial width of at least 60 [°] with respect to the circumferential direction and an axial width that is at least equal to the axial width of the working belt ply. An axially continuous ply made of a conductive metal cable is arranged between the carcass and the working ply closest to the rotational axis in the radial direction, and secondly oriented substantially parallel to the circumferential direction a metal element and the additional ply having at most equal tensile modulus in tensile modulus of at least equal to 0.7 S ₀ width and most extensible high working ply (circumferential reinforcing layer), between the two working belt ply Is arranged.

JP-A-56-82609 Japanese Patent No. 3764481

  In the pneumatic tires described in Patent Literature 1 and Patent Literature 2 described above, it is possible to suppress the radial growth on the outer side in the tire width direction of the tread portion unique to the low flatness tire by the circumferential reinforcing layer. However, since the tire growth in the tire width direction center of the tread portion is extremely small, it is difficult for the low flatness tire to have a uniform diameter growth from the tire width direction center of the tread portion to the outer side in the tire width direction. The uneven wear on the outer side in the tire width direction cannot be sufficiently suppressed.

  The present invention has been made in view of the above, and makes uniform the diameter growth from the center in the tire width direction of the tread portion to the outer side in the tire width direction, thereby improving uneven wear resistance on the outer side in the tire width direction of the tread portion. An object of the present invention is to provide a pneumatic tire that can handle the above.

  In order to solve the above-described problems and achieve the object, the pneumatic tire of the present invention has a cord having an angle of 10 [°] to 30 [°] with respect to the tire circumferential direction, and the cords cross each other And having at least two layers of cross belts laminated on the outer side in the tire radial direction of the carcass, a cord having an angle of 0 [°] or more and 5 [°] or less with respect to the tire circumferential direction, and divided in the tire width direction. A pneumatic tire including at least one circumferential reinforcing layer laminated on both sides of the cross belt in the tire width direction, and further including a rubber layer disposed between the cross belts at the center in the tire width direction. It is characterized by.

  According to this pneumatic tire, on both sides of the cross belt in the tire width direction, the circumferential reinforcing layer assists the cross belt in the hoop effect, thereby suppressing the diameter growth of the tread portion. On the other hand, at the center of the cross belt in the tire width direction, the rubber layer relaxes the cross-belt effect of the cross belt and allows a slight growth in the diameter of the tread portion. For this reason, since the diameter growth is made uniform from the center in the tire width direction of the tread portion to the outer side in the tire width direction, uneven wear resistance on the outer side in the tire width direction of the tread portion can be improved.

  In the pneumatic tire of the present invention, the modulus of 100% stretch of the rubber layer is equal to or less than the modulus of 100% stretch of the belt coat rubber covering the cord of the cross belt. .

  According to this pneumatic tire, the modulus at the time of 100% stretch of the rubber layer is made equal to or less than the modulus at the time of 100% stretch of the belt coat rubber of the cross belt, thereby mitigating the tagging effect of the cross belt by the rubber layer. The effect can be obtained remarkably.

  In the pneumatic tire of the present invention, the modulus of the belt coat rubber at 100 [%] elongation is 5.5 [MPa] or more and 7.5 [MPa] or less.

  If the modulus at 100% stretch of the belt coat rubber of the cross belt is less than 5.5 [MPa], the cross belt itself has too low a hoop effect, and the rubber layer can alleviate the cross belt hoop effect. It becomes excessive. On the other hand, if the modulus at 100% stretch of the belt coat rubber of the cross belt exceeds 7.5 [MPa], the cross belt itself has too high a hoop effect, and the rubber layer alleviates the cross belt hoop effect. Becomes difficult to obtain. Therefore, according to this pneumatic tire, by setting the modulus at 100% stretch of the belt coat rubber of the cross belt to 5.5 [MPa] or more and 7.5 [MPa] or less, the cross belt by the rubber layer is used. The effect of mitigating the hoop effect can be remarkably obtained.

  In the pneumatic tire of the present invention, the rubber layer has a modulus at 100 [%] elongation of 2.0 [MPa] or more and 6.5 [MPa] or less.

  If the modulus at the time of 100 [%] elongation of the rubber layer is less than 2.0 [MPa], the effect of mitigating the tagging effect of the cross belt by the rubber layer becomes excessive. On the other hand, if the modulus at 100 [%] elongation of the rubber layer exceeds 6.5 [MPa], it is difficult to obtain a mitigating effect on the cross belt due to the rubber layer. Therefore, according to this pneumatic tire, by setting the modulus at the time of 100 [%] elongation of the rubber layer to 2.0 [MPa] or more and 6.5 [MPa] or less, the effect of the cross belt due to the rubber layer can be reduced. The relaxation effect can be remarkably obtained.

  In the pneumatic tire of the present invention, the tire radial direction dimension T1 between the cords of the cross belt with the rubber layer interposed therebetween, and the tire diameter between the cords of the cross belt closest to the cross belt without the rubber layer interposed therebetween. The relationship with the direction dimension T2 is 1.2 ≦ T1 / T2 ≦ 4.0.

  If T1 / T2 is less than 1.2, the cords of the cross belt with the rubber layer interposed are too close, that is, the thickness of the rubber layer in the tire radial direction is too thin. It is difficult to obtain the relaxation effect. On the other hand, if T1 / T2 exceeds 4.0, the cords of the cross belt with the rubber layer interposed therebetween are too far apart, that is, the rubber layer is too thick in the tire radial direction. The effect of mitigating the effect is excessive. Therefore, according to this pneumatic tire, the relationship of 1.2 ≦ T1 / T2 ≦ 4.0 can remarkably obtain the effect of mitigating the cross belt tagging effect by the rubber layer.

  In the pneumatic tire of the present invention, the tire width direction dimension A of the rubber layer is in a range of 0.15 ≦ A / W ≦ 0.50 with respect to the cross-sectional width W of the carcass. .

  If the ratio A / W of the tire width direction dimension A of the rubber layer to the cross-sectional width W of the carcass is less than 0.15, the rubber layer is closer to the center in the tire width direction (tire equatorial plane). It becomes difficult to obtain the effect of mitigating the hoop effect. On the other hand, if A / W exceeds 0.50, the rubber layer spreads to near the outside in the tire width direction, so that the mitigating effect of the cross belt's tagging effect by the rubber layer becomes excessive. Therefore, according to this pneumatic tire, the relationship of 0.15 ≦ A / W ≦ 0.50 makes it possible to significantly obtain the effect of mitigating the cross belt tagging effect by the rubber layer.

  In the pneumatic tire of the present invention, the tire width direction interval B1 at the inner end in the tire width direction of each circumferential reinforcing layer is 0.20 ≦ B1 / W ≦ 0.50 with respect to the cross-sectional width W of the carcass. The tire width direction interval B2 at the outer end in the tire width direction of each circumferential reinforcing layer is in the range of 0.60 ≦ B2 / W ≦ 0.75 with respect to the cross-sectional width W of the carcass. It is characterized by.

  When the ratio B1 / W of the tire width direction interval B1 at the inner end in the tire width direction of each circumferential reinforcing layer divided with respect to the cross-sectional width W of the carcass is less than 0.20, the circumferential reinforcing layer is in the center in the tire width direction ( Since it spreads closer to the tire equatorial plane), the hoop effect by the circumferential reinforcing layer becomes excessive. On the other hand, when B1 / W exceeds 0.50, the circumferential reinforcing layer is disposed closer to the outer side in the tire width direction, so that it is difficult to obtain a tag effect by the circumferential reinforcing layer. Moreover, when the ratio B2 / W of the tire width direction interval B2 at the outer end in the tire width direction of each circumferential reinforcing layer divided with respect to the cross-sectional width W of the carcass is less than 0.60, the circumferential reinforcing layer is in the tire width direction. Since it is arranged closer to the center (tire equatorial plane), it is difficult to obtain a tag effect on the outer side in the tire width direction by the circumferential reinforcing layer. On the other hand, if B2 / W exceeds 0.75, the circumferential reinforcing layer is widely arranged on the outer side in the tire width direction, so that the tagging effect by the circumferential reinforcing layer becomes excessive. Therefore, according to this pneumatic tire, the relation of 0.20 ≦ B1 / W ≦ 0.50 and 0.60 ≦ B2 / W ≦ 0.75 is established, so that the tagging effect by the circumferential reinforcing layer is remarkable. Can get to.

  In the pneumatic tire according to the present invention, the circumferential reinforcing layer is disposed on at least one of the inner side of the cross belt in the tire radial direction or the outer side of the cross belt in the tire radial direction.

  According to this pneumatic tire, by appropriately selecting the arrangement of the circumferential reinforcing layer corresponding to the arrangement of the cross belt and the belt layer including the cross belt, it is possible to significantly obtain the tagging effect by the circumferential reinforcing layer. it can.

  In the pneumatic tire of the present invention, the flatness ratio is 70% or less.

  According to this pneumatic tire, in particular, when the flatness ratio is 70% or less, the diameter growth tends to be uneven from the center in the tire width direction of the tread portion to the outside in the tire width direction. Therefore, by applying a pneumatic tire having a flatness ratio of 70% or less, the diameter growth is made uniform from the center in the tire width direction of the tread portion to the outer side in the tire width direction, and the outer side of the tread portion in the tire width direction is uniformed. There is an advantage that the uneven wear suppression effect can be obtained more remarkably.

  The pneumatic tire according to the present invention can improve the uneven wear resistance of the tread portion on the outer side in the tire width direction by uniformizing the diameter growth from the center of the tread portion in the tire width direction to the outer side in the tire width direction.

FIG. 1 is a meridional sectional view of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a partially enlarged view of the pneumatic tire shown in FIG. FIG. 3 is a meridional sectional view of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 4 is a meridional sectional view of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 5 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial direction inner side refers to the side toward the rotation axis in the tire radial direction, the tire radial direction outer side. The term “side away from the rotation axis” in the tire radial direction. The tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction means the side toward the tire equator plane (tire equator line) C in the tire width direction, and the outer side in the tire width direction means the tire width. The side away from the tire equatorial plane C in the direction. The tire circumferential direction is a circumferential direction with the rotation axis as a central axis. The tire equatorial plane C is a plane that is orthogonal to the rotation axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1. The tire equator line is a line on the tire equator plane C and along the circumferential direction of the pneumatic tire 1. In the present embodiment, the same sign “C” as that of the tire equator plane is attached to the tire equator line. Since the pneumatic tire 1 described below is configured to be substantially symmetric about the tire equatorial plane C, the pneumatic tire 1 is cut along a plane passing through the rotation axis of the pneumatic tire 1. In the meridional sectional views (FIGS. 1, 3 and 4), only one side centered on the tire equatorial plane C (right side in FIGS. 1, 3 and 4) is shown and only the one side is shown. The description on the other side (left side in FIGS. 1, 3 and 4) is omitted.

  As shown in FIG. 1, the pneumatic tire 1 according to the present embodiment includes a tread portion 2, sidewall portions 3 and bead portions (not shown) on both sides thereof. Further, the pneumatic tire 1 has a carcass 4 and a belt layer 5.

  The tread portion 2 has a plurality of circumferential main grooves 22 extending in the tire circumferential direction on the outer circumferential surface thereof, that is, a tread surface 21 that comes into contact with the road surface during traveling, and a plurality of sections formed by the circumferential main grooves 22. And a rib 23 forming a land portion. For example, in the present embodiment, seven circumferential main grooves 22 are formed, and eight ribs 23 are formed by these circumferential main grooves 22. The outermost ribs 23 in the tire width direction form shoulder ribs 23a.

  The sidewall portion 3 is exposed to both outer sides in the tire width direction of the pneumatic tire 1 continuously with the tread portion 2. The side wall part 3 prevents trauma generated in the side wall part 3 from reaching the carcass 4.

  The bead portion has a bead core and a bead filler, though not explicitly shown in the drawing. The bead core is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead core supports the tension of the carcass 4 generated by the internal pressure of the pneumatic tire 1. The bead filler is disposed in a space formed by folding the carcass 4 outward in the tire width direction at the position of the bead core. The bead filler fixes the carcass 4 at the position of the bead core and adjusts the shape of the bead portion. Further, the bead filler increases the rigidity of the bead portion.

  The carcass 4 has a tread portion 2, both sidewall portions 3, and both bead portions continuously straddling both ends in the tire width direction while being wound around the pair of bead portions, and in a toroidal shape in the tire circumferential direction. It is wound around and constitutes the skeleton of the tire. The carcass 4 is a carcass cord such as organic fiber (nylon, polyester, rayon, etc.) or steel covered with a rubber material. A plurality of carcass cords of the carcass 4 are arranged side by side in the tire circumferential direction while being orthogonal to the tire equator line C of the pneumatic tire 1 and along the tire meridian direction (radial direction). The angle of the carcass cord in the carcass 4 with respect to the tire equator line C (tire circumferential direction) is substantially 90 [°], and from −5 [°] with respect to 90 [°] with respect to the tire equator line C. Includes angles in the range of +5 [°]. The carcass 4 serves as a pressure vessel when the pneumatic tire 1 is filled with air and supports a load applied to the pneumatic tire 1 by the internal pressure.

  The belt layer 5 is provided outside the carcass 4 in the tire radial direction in the tread portion 2 and both ends thereof are provided to reach the inside in the tire radial direction of the respective shoulder ribs 23a, and covers the carcass 4 in the tire circumferential direction in the tread portion 2. It is. The belt layer 5 has a belt in which a cord such as organic fiber (nylon, polyester, rayon, etc.) or steel is covered with a rubber material (belt coat rubber), and a plurality of these belts are laminated. In the present embodiment, a three-layer structure in which belts 51, 52, and 53 are laminated is formed.

  In the present embodiment, at least two layers of the belt layers 5 of the first and second belts 51 and 52 from the inner side in the tire radial direction have an angle of 10 [°] or more with respect to the tire circumferential direction, that is, the tire equator line C. It has a code of 30 [°] or less. Furthermore, the belts 51 and 52 are laminated so that the cords cross each other. And in this Embodiment, the belts 51 and 52 of the said structure are called the crossing belt 5A.

  The belt layer 5 gives a tightening force to the carcass 4 to increase the rigidity, and at the time of traveling of the vehicle on which the pneumatic tire 1 is mounted, the impact is reduced and trauma generated in the tread portion 2 reaches the carcass 4. To prevent that.

  The pneumatic tire 1 according to the present embodiment further includes a circumferential reinforcing layer 6 and a rubber layer 7.

  The circumferential reinforcing layer 6 is formed by being divided in the tire width direction in the tread portion 2, is laminated on both sides of the cross belt 5 </ b> A in the tire width direction, and is wound around the tire circumferential direction. The circumferential reinforcing layer 6 is made by covering a cord 6a such as organic fiber (nylon, polyester, rayon, etc.) or steel with a rubber material. The cord 6a has an angle of 0 [°] to 5 [°] with respect to the tire circumferential direction, and is substantially 0 [°] parallel to the tire circumferential direction. Although the circumferential reinforcing layer 6 is shown in FIG. 1 as a single layer, it may be composed of a plurality of layers.

  The rubber layer 7 is disposed between the belts 51 and 52 forming the cross belt 5A at the center in the tire width direction including the tire equatorial plane C in the tread portion 2, and is wound around in the tire circumferential direction. The rubber layer 7 does not have a cord and is formed of a rubber material. Further, in FIG. 1, the rubber layer 7 is shown as a form that is separated from the circumferential reinforcing layer 6 in the tire width direction and does not overlap with each other in the tire radial direction. May be provided overlapping each other.

  Thus, the pneumatic tire 1 of the present embodiment has a cord having an angle of 10 [°] to 30 [°] with respect to the tire circumferential direction, and the carcass tire radial direction so that the cords intersect each other. A cross belt 5A having at least two cross belts 5A laminated on the outside and a cord 6a having an angle with respect to the tire circumferential direction of 0 [°] or more and 5 [°] or less and divided in the tire width direction. And at least one circumferential reinforcing layer 6 laminated on both sides in the width direction, and further includes a rubber layer 7 disposed between the belts 51 and 52 of the cross belt 5A at the center in the tire width direction.

  According to this pneumatic tire 1, on both sides of the cross belt 5A in the tire width direction, the circumferential reinforcing layer 6 assists the tagging effect of the cross belt 5A, and the diameter growth of the tread portion 2 is suppressed. On the other hand, at the center of the cross belt 5A in the tire width direction, the rubber layer 7 relaxes the tagging effect of the cross belt 5A and allows the tread portion 2 to grow slightly in diameter. For this reason, since the diameter growth is made uniform from the center in the tire width direction of the tread portion 2 to the outer side in the tire width direction, it is possible to improve uneven wear resistance on the outer side in the tire width direction of the tread portion 2.

  Further, in the pneumatic tire 1 of the present embodiment, the modulus Ma at the time of 100 [%] elongation of the rubber layer 7 subjected to a tensile test at room temperature in accordance with JIS K6251 (using No. 3 dumbbell) is the cord of the cross belt 5A. It is preferable that Ma ≦ Mb with respect to the modulus Mb at the time of 100 [%] elongation of the belt coat rubber to be coated.

  According to the pneumatic tire 1, the modulus of the rubber layer 7 when 100 [%] is extended is equal to or less than the modulus of 100 [%] of the belt coat rubber of the cross belt 5 </ b> A. The effect of mitigating the hoop effect can be remarkably obtained.

  In the pneumatic tire 1 of the present embodiment, the modulus Mb at the time of 100 [%] elongation of the belt coat rubber covering the cord of the cross belt 5A is 5.5 [MPa] ≦ Mb ≦ 7.5 [MPa]. It is preferable that

  In the above-mentioned range of Ma ≦ Mb, if the modulus Mb at the time of 100 [%] elongation of the belt coat rubber of the cross belt 5A is less than 5.5 [MPa], the tagging effect of the cross belt 5A itself is too low, The mitigating effect of the cross effect of the cross belt 5A by the rubber layer 7 becomes excessive. On the other hand, when the modulus [Mb] of the belt coat rubber of the cross belt 5A at 100 [%] elongation exceeds 7.5 [MPa], the cross belt 5A itself has too high a hoop effect, and the cross belt 5A is formed by the rubber layer 7. It becomes difficult to obtain the effect of mitigating the taga effect. Therefore, according to this pneumatic tire 1, by setting the modulus Mb at the time of 100 [%] elongation of the belt coat rubber of the cross belt 5A to 5.5 [MPa] or more and 7.5 [MPa] or less, the rubber layer 7 can significantly relieve the tagging effect of the cross belt 5A.

  In the pneumatic tire 1 of the present embodiment, the modulus Ma at the time of 100 [%] elongation of the rubber layer 7 is preferably 2.0 [MPa] ≦ Ma ≦ 6.5 [MPa].

  When the modulus Ma at 100 [%] elongation of the rubber layer 7 is less than 2.0 [MPa] in the range of Ma ≦ Mb described above, the effect of mitigating the tagging effect of the cross belt 5A by the rubber layer 7 is excessive. Become. On the other hand, if the modulus Ma at the time of 100 [%] elongation of the rubber layer 7 exceeds 6.5 [MPa], it is difficult to obtain the effect of mitigating the tagging effect of the cross belt 5A by the rubber layer 7. Therefore, according to the pneumatic tire 1, the crossing belt formed by the rubber layer 7 is obtained by setting the modulus Ma when the rubber layer 7 is stretched to 100 [%] to 2.0 [MPa] or more and 6.5 [MPa] or less. It becomes possible to remarkably obtain the relaxation effect of the 5A tag effect.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 2, the tire radial direction dimension T1 between the cords 51a and 52a of the belts 51 and 52 forming the cross belt 5A with the rubber layer 7 interposed therebetween, The relationship between the closest cords 51a and 52a of the belts 51 and 52 constituting the cross belt 5A without the rubber layer 7 between them and the tire radial direction dimension T2 is 1.2 ≦ T1 / T2 ≦ 4.0. Preferably there is.

  If T1 / T2 is less than 1.2, the cords 51a, 52a of the belts 51, 52 of the cross belt 5A with the rubber layer 7 therebetween are too close, that is, the thickness of the rubber layer 7 in the tire radial direction is thin. Therefore, it becomes difficult to obtain the effect of mitigating the tagging effect of the cross belt 5A by the rubber layer 7. On the other hand, when T1 / T2 exceeds 4.0, the cords 51a and 52a of the belts 51 and 52 of the cross belt 5A with the rubber layer 7 interposed therebetween are too far apart, that is, the thickness of the rubber layer 7 in the tire radial direction is too large. Since it is too thick, the effect of mitigating the tagging effect of the cross belt 5A by the rubber layer 7 becomes excessive. Therefore, according to the pneumatic tire 1, the relationship of 1.2 ≦ T1 / T2 ≦ 4.0 makes it possible to significantly obtain the effect of mitigating the tagging effect of the cross belt 5 </ b> A by the rubber layer 7. Become.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 1, the tire width direction dimension A of the rubber layer 7 is 0.15 ≦ A / W ≦ 0. The range is preferably 50 (15 [%] ≦ A / W ≦ 50 [%]).

  Here, the cross-sectional width W of the carcass 4 is the largest tire width direction dimension of the carcass 4 in the meridian cross section. When the ratio A / W of the tire width direction dimension A of the rubber layer 7 to the cross-sectional width W of the carcass 4 is less than 0.15 (15 [%]), the rubber layer 7 is centered in the tire width direction (tire equatorial plane C). ), The effect of mitigating the tagging effect of the cross belt 5A by the rubber layer 7 is difficult to obtain. On the other hand, when A / W exceeds 0.50 (50 [%]), the rubber layer 7 spreads to near the outside in the tire width direction, so that the effect of mitigating the tagging effect of the cross belt 5A by the rubber layer 7 becomes excessive. Therefore, according to this pneumatic tire 1, the cross belt formed by the rubber layer 7 is obtained by setting the relationship of 0.15 ≦ A / W ≦ 0.50 (15 [%] ≦ A / W ≦ 50 [%]). It becomes possible to remarkably obtain the relaxation effect of the 5A tag effect.

  Further, in the pneumatic tire 1 of the present embodiment, as shown in FIG. 1, the tire width direction interval B <b> 1 at the inner end in the tire width direction of each circumferential reinforcing layer 6 is the cross-sectional width W of the carcass 4. On the other hand, it is in the range of 0.20 ≦ B1 / W ≦ 0.50 (20 [%] ≦ B1 / W ≦ 50 [%]), and the tire width direction interval at the outer end in the tire width direction of each circumferential reinforcing layer 6 B2 is preferably in a range of 0.60 ≦ B2 / W ≦ 0.75 (60 [%] ≦ B2 / W ≦ 75 [%]) with respect to the cross-sectional width W of the carcass 4.

  When the ratio B1 / W of the tire width direction interval B1 at the inner end in the tire width direction of each circumferential reinforcing layer 6 divided with respect to the cross-sectional width W of the carcass 4 is less than 0.20 (20 [%]), the circumferential direction Since the reinforcing layer 6 extends toward the center in the tire width direction (tire equatorial plane C), the hoop effect by the circumferential reinforcing layer 6 becomes excessive. On the other hand, if B1 / W exceeds 0.50 (50 [%]), the circumferential reinforcing layer 6 is disposed closer to the outer side in the tire width direction, so that it is difficult to obtain a hoop effect by the circumferential reinforcing layer 6. And if ratio B2 / W of the tire width direction space | interval B2 of the tire width direction outer side end of each circumferential direction reinforcement layer 6 divided | segmented with respect to the cross-sectional width W of the carcass 4 is less than 0.60 (60 [%]), Since the circumferential reinforcing layer 6 is disposed closer to the center in the tire width direction (tire equatorial plane C), it is difficult to obtain a tag effect on the outer side in the tire width direction by the circumferential reinforcing layer 6. On the other hand, when B2 / W exceeds 0.75 (75 [%]), the circumferential reinforcing layer 6 is widely arranged on the outer side in the tire width direction, and thus the tagging effect by the circumferential reinforcing layer 6 becomes excessive. Therefore, according to this pneumatic tire 1, 0.20 ≦ B1 / W ≦ 0.50 (20 [%] ≦ B1 / W ≦ 50 [%]) and 0.60 ≦ B2 / W ≦ 0.75 By setting the relationship of (60 [%] ≦ B2 / W ≦ 75 [%]), it is possible to obtain a remarkable tagging effect by the circumferential reinforcing layer 6.

  Further, in the pneumatic tire 1 of the present embodiment, the circumferential reinforcing layer 6 is provided on the inner side in the tire radial direction of the cross belt 5A or on the outer side in the tire radial direction of the cross belt 5A, as shown in FIGS. It suffices if it is arranged on at least one of the above.

  Specifically, FIG. 1 shows a form in which the circumferential reinforcing layer 6 is arranged on the inner side in the tire radial direction of the cross belt 5A. Moreover, in FIG. 3, the circumferential direction reinforcement layer 6 shows the form arrange | positioned at the tire radial direction outer side of the cross belt 5A. FIG. 4 shows a form in which the circumferential reinforcing layer 6 is disposed on the inner side in the tire width direction and the outer side in the tire radial direction of the cross belt 5A.

  According to this pneumatic tire 1, by selecting the arrangement of the circumferential reinforcing layer 6 appropriately corresponding to the arrangement of the intersecting belt 5 </ b> A and the belt layer 5 including the intersecting belt 5 </ b> A, the tagging effect by the circumferential reinforcing layer 6 is achieved. Can be obtained remarkably.

  In the pneumatic tire 1 of the present embodiment, the flatness ratio is preferably 70 [%] or less.

  Here, the flatness ratio is a ratio of the cross-sectional height H to the cross-sectional width Wmax of the tire, as shown in FIG. The tire cross-sectional width Wmax is a width obtained by removing a pattern or characters on the side surface of the tire from the total width of the tire. The cross-sectional height H of the tire is ½ of the difference between the outer diameter of the tire and the rim diameter. The total width of the tire is the straight distance between the sidewall portions 3 that includes all the patterns and characters on the side of the tire when the tire is mounted on the specified rim, is at the normal internal pressure, and is unloaded (maximum dimension in the tire width direction). It is. The outer diameter of the tire is the outer diameter (maximum dimension in the tire radial direction) of the tire in a no-load state when the tire is mounted on the specified rim and has a normal internal pressure.

  The regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “maximum air pressure” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO.

  According to this pneumatic tire, in particular, when the flatness ratio is 70% or less, the diameter growth tends to be uneven from the center in the tire width direction of the tread portion 2 to the outside in the tire width direction. Therefore, by applying a pneumatic tire having a flatness ratio of 70% or less, the diameter growth is uniform from the center of the tread portion 2 in the tire width direction to the outer side in the tire width direction, and the tread portion 2 in the tire width direction. There is an advantage that the effect of suppressing the uneven wear on the outside can be obtained more remarkably.

  Moreover, it is preferable that the pneumatic tire 1 of this Embodiment is applied to the heavy load pneumatic tire.

  According to this pneumatic tire, the heavy-duty pneumatic tire is used for trucks and buses that run at a high speed for a long time, and therefore, uneven wear on the outer side in the tire width direction of the tread portion 2 tends to occur. Therefore, there is an advantage that the effect of suppressing the uneven wear on the outer side in the tire width direction of the tread portion 2 can be obtained more significantly by using the heavy duty pneumatic tire as an application target.

  In this example, a performance test on the amount of uneven wear on the outer side in the tire width direction of the shoulder portion was performed for a plurality of types of pneumatic tires having different conditions (see FIG. 5).

  In this performance test, a pneumatic tire having a tire size of 445 / 50R22.5 is mounted on a 22.5 × 14.00 rim, filled with air pressure of 830 [kPa], and mounted on a test vehicle (3-axle trailer). Thus, a load of 4625 [kg] was applied.

  In the evaluation method of the uneven wear amount, the test vehicle travels 100,000 km on the paved road, and the wear amount obtained by subtracting the groove depth after traveling from the groove depth before traveling is the outermost in the tire width direction. A value obtained by subtracting the wear amount of the circumferential main groove at the center in the tire width direction from the wear amount of the circumferential main groove is defined as the uneven wear amount on the outer side in the tire width direction, and the conventional example is evaluated as a reference. This evaluation is indicated by an index value based on the conventional pneumatic tire (100). The smaller the index value, the smaller the uneven wear amount and the better.

  In the conventional pneumatic tire, the belt layer has a four-layer structure, the second belt and the third belt from the inner side in the tire radial direction are configured as cross belts, and does not include the circumferential reinforcing layer and the rubber layer. Moreover, although the pneumatic tire of a comparative example is comprised as a circumferential direction reinforcement layer, the 1st belt of a prior art example is not provided with the rubber layer.

  On the other hand, the pneumatic tires of Examples 1 to 10 are configured by using the No. 1 belt of the conventional example as a circumferential reinforcing layer, including a rubber layer, and the modulus at the time of 100% stretch of the belt coat rubber. Is within the prescribed range. In the pneumatic tire of Example 2, the modulus of the rubber layer at 100 [%] elongation is equal to or less than the modulus of 100 [%] elongation of the belt coat rubber of the cross belt. Further, in the pneumatic tire of Example 3, the modulus at the time of 100 [%] elongation of the rubber layer is within a specified range. Further, in the pneumatic tire of Example 4, the ratio T1 / T2 of the tire radial direction dimension between the cords of the intersecting belt is set within a specified range. In the pneumatic tire of Example 5, the ratio A / W between the tire width direction dimension A of the rubber layer and the cross-sectional width W of the carcass is within a specified range. Further, the pneumatic tires of Examples 6 to 10 have the ratio B1 / W between the tire width direction interval B1 and the carcass at the inner end in the tire width direction of the circumferential reinforcing layer, and the outer side in the tire width direction of the circumferential reinforcing layer. The ratio B2 / W between the end width B2 of the tire width and the cross-sectional width W of the carcass is within a specified range.

  As shown in the test results of FIG. 5, it can be seen that the pneumatic tires of Examples 1 to 10 have a small amount of uneven wear on the outer side in the tire width direction and are excellent in uneven wear resistance.

  As described above, the pneumatic tire according to the present invention improves the uneven wear resistance of the tread portion on the outer side in the tire width direction by uniformizing the diameter growth from the center in the tire width direction to the outer side in the tire width direction. Suitable for

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Carcass 5 Belt layer 5A Cross belt 51,52,53 Belt 51a, 52a Cord 6 Circumferential reinforcement layer 6a Cord 7 Rubber layer C Tire equatorial plane (tire equatorial line)
A Dimension in the tire width direction of the rubber layer B1 Interval in the tire width direction at the inner end in the tire width direction of the circumferential reinforcing layer B2 Interval in the tire width direction at the outer end in the tire width direction of the circumferential reinforcing layer T1 Cross belt with the rubber layer in between Tire radial dimension between two cords T2 Tire radial dimension between the closest cords of the crossed belt without a rubber layer in between W Carcass cross-sectional width

Claims (9)

An at least two-layered cross belt having a cord with an angle with respect to the tire circumferential direction of 10 [°] or more and 30 [°] or less and laminated on the outer side in the tire radial direction of the carcass so that the cords cross each other; At least one circumferential reinforcing layer having a cord with an angle with respect to the circumferential direction of 0 [°] or more and 5 [°] or less and divided in the tire width direction and laminated on both sides of the cross belt in the tire width direction; In a pneumatic tire comprising:
A pneumatic tire comprising a rubber layer disposed between the cross belts at a center in a tire width direction.   2. The pneumatic tire according to claim 1, wherein a modulus of 100% stretch of the rubber layer is equal to or less than a modulus of 100% stretch of the belt coat rubber covering the cord of the cross belt.   3. The pneumatic tire according to claim 2, wherein a modulus at 100 [%] elongation of the belt coat rubber is 5.5 [MPa] or more and 7.5 [MPa] or less.   4. The pneumatic tire according to claim 2, wherein a modulus at 100 [%] elongation of the rubber layer is 2.0 [MPa] or more and 6.5 [MPa] or less.   The relationship between the tire radial dimension T1 between the cords of the cross belt with the rubber layer in between and the tire radial dimension T2 between the closest cords of the cross belt without the rubber layer in between. The pneumatic tire according to claim 1, wherein 2 ≦ T1 / T2 ≦ 4.0.   6. The tire width direction dimension A of the rubber layer is in a range of 0.15 ≦ A / W ≦ 0.50 with respect to the cross-sectional width W of the carcass. Pneumatic tire described in 2.   The tire width direction interval B1 at the inner end in the tire width direction of each circumferential reinforcing layer is in a range of 0.20 ≦ B1 / W ≦ 0.50 with respect to the cross-sectional width W of the carcass, and each circumferential reinforcing The tire width direction interval B2 between the tire width direction outer ends of the layers is in a range of 0.60 ≦ B2 / W ≦ 0.75 with respect to the cross-sectional width W of the carcass. The pneumatic tire according to any one of the above.   The said circumferential direction reinforcement layer is arrange | positioned at least one of the tire radial direction inner side of the said cross belt, or the tire radial direction outer side of the said cross belt, The Claim 1 characterized by the above-mentioned. Pneumatic tire.   The pneumatic tire according to any one of claims 1 to 8, wherein the flatness ratio is 70% or less.

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