JP2009101909A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for compatibly attaining the improved durability and reduced weight of a belt layer. <P>SOLUTION: The pneumatic tire comprises the belt layer 3 having at least two crossing belts 31, 32 whose cords have angles α1 of 10°≤α1≤30° to a tire peripheral direction in the extending direction and which are laminated on the outside of a carcass 2 in a tire radial direction so that the cords cross each other. Herein, a one-layer composite belt is provided which consists of a crossing belt portion 321 formed as part of the crossing belt 32 and arranged in a center region of a tread 4, peripheral reinforcing belt portions 322 arranged side by side on both sides of the crossing belt portion in a tire cross direction with their cords having angles α2 of 0°≤α2≤5° to the tire peripheral direction in the extending direction, and cross reinforcing belt portions 323 arranged side by side on both sides of the peripheral reinforcing belt portions in the tire cross direction in a shoulder region of the tread with their cords having angles α3 of 10°≤α3≤90° to the tire peripheral direction in the extending direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can achieve both improvement in durability and weight reduction.

  Mainly heavy-duty pneumatic tires that are super flat (for example, a flat rate of 80% or less) are desired to have durability when traveling at high speed for long distances. Conventionally, this type of pneumatic tire has a non-extensible cable having an angle of 10 to 45 ° with respect to the circumferential direction of the tire and includes at least two working plies (belt layers) in which the cables cross each other, The working tire is a pneumatic tire having a tire width direction dimension that is laminated on a radially outer side of a radial carcass having a maximum tire width direction dimension and has a tire width direction dimension equal to 80% of the radial carcass tire width direction dimension. The pneumatic tire includes an additional reinforcing body that is at least 15% smaller than the smallest working ply in the width direction of the tire, and the additional reinforcing body includes a substantially non-extensible cable in the radial direction. And a central portion having a tire width direction dimension equal to at least 45% of the radial carcass tire width dimension, and equal to the tensile elastic modulus of the most extensible working ply and at least 10 of the radial carcass tire width dimension. Some are formed of two side portions having a tire width direction dimension equal to% (see, for example, Patent Document 1).

JP 2002-544044 A

  In the conventional pneumatic tire described above, in addition to the two working plies where the cables cross each other, an additional reinforcing body is provided to improve the durability. It is at least 15% smaller than the minimum working ply. For this reason, it is difficult to achieve durability in the shoulder region of the tread, and belt edge separation (separation) may occur at the outer end portion in the tire width direction between the two working plies. In addition, the tire weight increases because an additional reinforcement is added to the working ply in order to improve durability.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can make durability improvement and weight reduction of a belt layer compatible.

  In order to achieve the above object, in the pneumatic tire according to the present invention, the carcass is formed such that an angle α1 in the extending direction with respect to the tire circumferential direction has a cord of 10 ° ≦ α1 ≦ 30 °, and the cords cross each other. A pneumatic tire having a belt layer having at least two cross belts laminated on the outer side in the tire radial direction of the tire, and a cross belt portion disposed in a center region of the tread as one of the cross belts; A circumferential reinforcing belt portion that is arranged in parallel on both sides of the cross belt portion in the tire width direction and has a cord in which an angle α2 in the extending direction with respect to the tire circumferential direction is 0 ° ≦ α2 ≦ 5 °, and the circumferential reinforcing belt portion Width direction with cords arranged side by side in the tire width direction and arranged in the shoulder region of the tread and having an angle α3 in the extending direction relative to the tire circumferential direction of 10 ° ≦ α3 ≦ 90 ° Characterized by comprising a composite belt of one layer made of a strong belt portion.

  According to this pneumatic tire, each cross belt including the cross belt portion acts as a low-angle cross belt layer with a cord having an angle α1 of 10 ° ≦ α1 ≦ 30 °, and the circumferential reinforcing belt portion has 0 ° ≦ It acts as a tire circumferential reinforcing layer by a cord having an angle α2 of α2 ≦ 5 °, and the shape of the pneumatic tire filled with air is held by the cross belt and the circumferential reinforcing belt portion. Further, in the range where the tagging effect is large, such as the center area of the tread, the cross belt portion supports the internal pressure of the air filled in the pneumatic tire. In the range between the center area and the shoulder area of the tread and in the range where the tagging effect is small and the diameter growth is likely to be large as in the vicinity of the main groove on the outer side in the tire width direction of the tread, the circumferential reinforcing belt portion Supports internal pressure. Further, in the shoulder region of the tread and in the range where the burden of supporting the internal pressure of air by the carcass is increased like the outer end portion of the belt layer in the tire width direction, the width is increased by the cord of the angle α3 of 10 ° ≦ α3 ≦ 90 °. The direction reinforcing belt portion follows the pulling in the tire circumferential direction in the shoulder region, and reduces distortion at the outer end portion in the tire width direction of the belt layer. As a result, the durability of the belt layer can be improved.

  In addition, since the cross belt portion, the circumferential reinforcing belt portion and the width reinforcing belt portion are configured as a single-layer composite belt, each of which is divided into functions, a layer of a reinforcing belt is added to each cross belt. Without further increase, the weight of the pneumatic tire can be reduced while improving the durability of the belt layer.

  In the pneumatic tire according to the present invention, the one-layer composite belt is disposed on the outer side in the tire radial direction of the cross belt that does not constitute the composite belt.

  According to this pneumatic tire, in the shoulder region of the tread, the width-direction reinforcing belt portion having the cord of the angle α3 of 10 ° ≦ α3 ≦ 90 ° is disposed on the outer side in the tire radial direction of the cross belt that does not constitute the composite belt. Therefore, belt edge separation (separation) at the outer end of the cross belt in the tire width direction is prevented. As a result, the durability of the belt layer can be further improved.

  In the pneumatic tire according to the present invention, the width direction reinforcing belt portion has a cord in which an angle α3 in the extending direction with respect to the tire circumferential direction is 45 ° ≦ α3 ≦ 90 °.

  According to this pneumatic tire, since the width direction reinforcing belt portion has the cord of the angle α3 of 45 ° ≦ α3 ≦ 90 °, the tire width of the belt layer can be tracked by pulling in the tire circumferential direction in the shoulder region. Since the distortion at the outer end portion in the direction is reduced, the durability of the belt layer can be further improved.

  In the pneumatic tire according to the present invention, in the range from the tire equatorial plane to the tire width direction half width, the cross belt portion has a tire width direction dimension A of 0. 0 relative to the carcass tire width direction dimension W. 4 ≦ A / W ≦ 0.5, and the circumferential reinforcing belt portion has a tire width direction dimension B from the tire equatorial plane to the tire width direction outer end of 0 relative to the carcass dimension W. .6 ≦ B / W ≦ 0.75, and the width direction reinforcing belt portion is a tire width direction dimension from the outer end in the tire width direction of the circumferential reinforcing belt portion to the outer end in the tire width direction. C is set in a range of 0.1 ≦ C / W with respect to the dimension W of the carcass.

  According to this pneumatic tire, each belt portion is arranged corresponding to the center region, shoulder region, and the region between the treads to sufficiently exhibit the tagging effect, so the durability of the belt layer can be further improved.

  In the pneumatic tire according to the present invention, when the sum of the cord strengths in the tire circumferential direction of the circumferential reinforcing belt portion and each of the cross belts is ΣN, the cord strength Ni of the circumferential reinforcing belt portion is 0. It has a relationship of 3 ≦ Ni / ΣN ≦ 0.5.

  According to this pneumatic tire, the internal pressure maintaining function can be sufficiently exhibited while eliminating the bending of the circumferential reinforcing belt portion within the above range. That is, if the cord strength Ni of the circumferential reinforcing belt portion is smaller than 0.3, the internal pressure holding function is insufficient, and if the cord strength Ni is larger than 0.5, the tension applied to the circumferential reinforcing belt portion becomes excessive, and the belt Folding occurs.

  Moreover, in the pneumatic tire according to the present invention, the width direction reinforcing belt portion has a cord having a cord diameter equal to or larger than that of the intersecting belt portion, and the number of cord ends in a predetermined length in the cord arrangement direction is The number of cord ends of the cross belt portion is equal to or less.

  According to this pneumatic tire, the belt edge is secured while ensuring the belt strength by the width direction reinforcing belt having the cord diameter larger than that of the cross belt portion and the number of cord ends in the cord arrangement direction being smaller than that of the cross belt portion. Since the stress of the part is relaxed, the durability of the belt layer can be further improved.

  Further, in the pneumatic tire according to the present invention, the carcass has a cord that is disposed on the outer surface in the tire radial direction and has an angle α4 in the extending direction with respect to the tire circumferential direction of 45 ° ≦ α4 ≦ 90 °, and The tire width direction outer end is further provided with a high-angle belt arranged in the range of the width direction reinforcing belt portion in the tire width direction.

  According to this pneumatic tire, the high-angle belt can cooperate with each belt portion to further improve the durability of the belt layer.

  Further, in the pneumatic tire according to the present invention, the angle α5 with respect to the tire circumferential direction is 10 in the same direction as the cord of the cross belt, which is disposed on the tire radial direction outer side of the cross belt disposed on the tire radial direction outer side. It further includes a protective belt having a cord of ° ≦ α5 ≦ 30 ° and having its own outer end in the tire width direction disposed in a range of the width direction reinforcing belt portion in the tire width direction.

  According to this pneumatic tire, the protection belt can cooperate with each belt portion to further improve the durability of the belt layer.

  The pneumatic tire according to the present invention has a maximum tire width direction dimension of 300 mm or more.

  In general, in a wide pneumatic tire, the durability of the belt layer tends to be lowered. Therefore, the effect of improving the durability of the belt layer can be obtained more remarkably by applying the configuration of the pneumatic tire forming the belt layer as described above.

  Moreover, the pneumatic tire according to the present invention has a flatness ratio of 70% or less.

  In general, in a low-flat rate pneumatic tire, the durability of the belt layer tends to decrease. Therefore, the effect of improving the durability of the belt layer can be obtained more remarkably by applying the configuration of the pneumatic tire forming the belt layer as described above.

  In the pneumatic tire according to the present invention, the cross belt portion supports the internal pressure of the air filled in the pneumatic tire in a range having a large tagging effect such as the center region of the tread. In the range between the center area and the shoulder area of the tread and in the range where the tagging effect is small and the diameter growth is likely to be large as in the vicinity of the main groove on the outer side in the tire width direction of the tread, the circumferential reinforcing belt portion Supports internal pressure. Further, in the shoulder region of the tread and in the range where the burden of supporting the internal pressure of air by the carcass is increased like the outer end portion of the belt layer in the tire width direction, the width is increased by the cord of the angle α3 of 10 ° ≦ α3 ≦ 90 °. The direction reinforcing belt portion follows the pulling in the tire circumferential direction in the shoulder region, and reduces distortion at the outer end portion in the tire width direction of the belt layer. As a result, the durability of the belt layer can be improved. In addition, since the cross belt portion, the circumferential reinforcing belt portion and the width reinforcing belt portion are configured as a single-layer composite belt, each of which is divided into functions, a layer of a reinforcing belt is added to each cross belt. Without further increase, the weight of the pneumatic tire can be reduced while improving the durability of the belt layer.

  Embodiments of a pneumatic tire according to 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 width direction means a direction parallel to the rotation axis of the pneumatic tire, the inner side in the tire width direction means the side toward the tire equator in the tire width direction, and the outer side in the tire width direction means the tire width. The side away from the tire equator in the direction. Further, the tire radial direction refers to a direction orthogonal to the rotation axis, the tire radial inner side is the side toward the rotation axis in the tire radial direction, and the tire radial direction outer side is the side away from the rotation axis in the tire radial direction. Say. The tire circumferential direction is a circumferential direction with the rotation axis as a central axis.

  FIG. 1 is a meridional sectional view showing a pneumatic tire according to an embodiment of the present invention. The pneumatic tire 1 according to the present embodiment is intended for a heavy-duty pneumatic radial tire having a maximum tire width direction dimension Wmax of 300 mm or more and a flatness of 70% or less. Here, as shown in FIG. 1, the flatness ratio is a ratio of the tire height H with respect to the maximum tire width direction dimension Wmax. The maximum tire width direction dimension Wmax is the dimension in the tire width direction of the outermost portions in the tire width direction among the opposing sidewall portions located at both ends in the tire width direction, that is, a pair of sidewalls. This is the distance in the tire width direction between the portions that are farthest from the tire equatorial plane 50 in the tire width direction. Further, the tire height H extends in the tire radial direction from the inner end (that is, the rim base position) of the bead portion (not shown) to the center crown CL that is the intersection of the tire equatorial plane 50 and the tread surface 41. It is the tire cross section height along. In addition, the width direction dimension means a dimension in a direction parallel to the tire width direction (the rotation axis of the pneumatic tire).

  The pneumatic tire 1 includes a carcass 2 and a belt layer 3. The carcass 2 is formed in a toroid-like manner across a pair of bead portions (not shown), and constitutes a tire skeleton. The belt layer 3 is formed by laminating a plurality of belts 31, 32, 33, and 34 and is disposed on the outer side in the tire radial direction of the carcass 2 to cover the carcass 2 in the tire circumferential direction. A rubber material is disposed on the outer side in the tire radial direction of the belt layer 3 to form a tread 4. The tread 4 is exposed to the outside of the pneumatic tire 1, and the surface thereof is formed as a tread surface 41 that is an outline of the tread 4 and serves as a tread surface. The tread surface 41 is formed with a circumferential main groove 41a formed continuously in the tire circumferential direction.

  The belt layer 3 is configured by stacking two cross belts 31, 32, a high-angle belt 33, and a protection belt 34 on the outer side in the tire radial direction of the carcass 2. These belts 31, 32, 33, 34 are formed by covering a plurality of cords made of an elastic material such as a steel fiber material or an organic fiber material with rubber.

  The cross belts 31 and 32 are arranged with cords in which an angle α1 in the extending direction with respect to the tire circumferential direction is 10 ° ≦ α1 ≦ 30 °, and are sequentially laminated on the outer side in the tire radial direction of the carcass 2 so that the cords cross each other. ing. Of these two cross belts 31 and 32, the cross belt 32 disposed on the outer side in the tire radial direction forms a cross belt portion 321 disposed in the center region of the tread 4. A circumferential reinforcing belt portion 322 is juxtaposed on the outer side in the tire width direction of the cross belt portion 321, and the outer side in the tire width direction of the circumferential reinforcing belt portion 322 and in the shoulder region of the tread 4 in the width direction. A reinforcing belt portion 323 is provided side by side. The cross belt portion 321, the circumferential direction reinforcing belt portion 322, and the width direction reinforcing belt portion 323 form a single layer composite belt.

  As described above, the intersecting belt portion 321 forms the intersecting belt 32, and cords in which the angle α1 in the extending direction with respect to the tire circumferential direction is 10 ° ≦ α1 ≦ 30 ° are arranged in the tire width direction. As shown in FIG. 1, the cross belt portion 321 has a tire width direction dimension A of 0.4 ≦ A with respect to the tire width direction dimension W of the carcass 2 in the range from the tire equatorial plane 50 to the tire width direction half width. /W≦0.5 is set. The center region of the tread 4 in which the cross belt portion 321 is disposed in this way is a central region of the tread 4 including the tire equator, and the range in which the cross belt portion 321 is disposed (0.4 ≦ A /W≦0.5).

The circumferential reinforcing belt portion 322 is formed by aligning a plurality of cords made of an elastic material such as a steel fiber material or an organic fiber material and covering them with rubber. The cords of the circumferential reinforcing belt portions 322 are arranged in the tire width direction such that the angle α2 in the extending direction with respect to the tire circumferential direction is 0 ° ≦ α2 ≦ 5 °. As shown in FIG. 1, the circumferential reinforcing belt portion 322 has a tire width from the tire equatorial plane 50 to the outer end in the tire width direction (end on the outer side in the tire width direction) in the range from the tire equatorial plane 50 to the half width in the tire width direction. The direction dimension B is set in a range of 0.6 ≦ B / W ≦ 0.75 with respect to the dimension W of the carcass 2. Further, the circumferential reinforcing belt portion 322 has a cord strength Ni of 0 in the circumferential reinforcing belt portion 322 when the sum of the cord strengths in the tire circumferential direction of the circumferential reinforcing belt portion 322 and the cross belts 32 and 33 is ΣN. .3 ≦ Ni / ΣN ≦ 0.5. Here, the cord strength in the tire circumferential direction is (cord breaking strength) × (number of cord ends (pieces / 50 mm)) × (cos [cord angle] ² ). As described above, the circumferential reinforcing belt portion 322 has a relationship of 0.3 ≦ Ni / ΣN ≦ 0.5, thereby sufficiently exhibiting the internal pressure holding function while eliminating the bending of the circumferential reinforcing belt portion 322 itself. it can. That is, if the cord strength Ni of the circumferential reinforcing belt portion 322 is smaller than 0.3, the internal pressure holding function is insufficient, and if the cord strength Ni is larger than 0.5, the tension applied to the circumferential reinforcing belt portion 322 becomes excessive. The belt breaks. The inner end in the tire width direction (end on the inner side in the tire width direction) of the circumferential reinforcing belt portion 322 may be in contact with the outer end in the tire width direction of the cross belt portion 321, or the tire of the cross belt portion 321. A minute gap may be provided without contacting the outer end in the width direction.

  The width-direction reinforcing belt portion 323 is formed by arranging a plurality of cords made of an elastic material such as a steel fiber material or an organic fiber material and covering them with rubber. The cords of the width direction reinforcing belt portions 323 are arranged in the tire width direction such that the angle α3 in the extending direction with respect to the tire circumferential direction is 10 ° ≦ α3 ≦ 90 °, preferably 45 ° ≦ α3 ≦ 90 °. As shown in FIG. 1, the width direction reinforcing belt portion 323 is formed from the tire width direction outer end of the circumferential direction reinforcing belt portion 322 to its own tire width direction outer end in the range from the tire equatorial plane 50 to the tire width direction half width. The tire width direction dimension C is set in a range of 0.1 ≦ C / W with respect to the dimension W of the carcass 2. Further, the width direction reinforcing belt portion 323 has a cord that is equal to or larger than the cord diameter of the intersecting belt portion 321. Further, the width direction reinforcing belt portion 323 is formed such that the number of cord ends, which is the number of cords driven into a predetermined length (for example, unit length 50 mm) in the arrangement direction, is equal to or less than the number of cord ends of the cross belt portion 321. That is, the width direction reinforcing belt portion 323 is formed such that the cord diameter is thicker than that of the cross belt portion 321 and the number of cord ends is smaller than that of the cross belt portion 321. Further, the width direction reinforcing belt portion 323 has a cord larger than the cord diameter of the cross belt portion 321 and the number of cord ends in a predetermined length in the cord arrangement direction is equal to or less than the number of cord ends of the cross belt portion 321. By doing so, since the stress at the belt edge portion can be relaxed while ensuring the belt strength, the durability of the belt layer 3 can be further improved. The inner end of the width direction reinforcing belt portion 323 in the tire width direction may be in contact with the outer end of the circumferential direction reinforcing belt portion 322 in the tire width direction, or the outer end of the circumferential direction reinforcing belt portion 322 in the tire width direction. A minute gap may be provided without contacting the surface. The shoulder region of the tread 4 in which the width direction reinforcing belt portion 323 is arranged in this manner is a region of the end portion of the tread 4 in the tire width direction (a portion in a predetermined range from the outer end in the tire width direction), and the belt layer. 3 in which the width direction end portion is located, and includes a range (0.1 ≦ C / W) in which the width direction reinforcing belt portion 323 is disposed.

  The single-layer composite belt is not limited to the cross belt 32, and the cross belt 31 disposed on the inner side in the tire radial direction may be configured as a composite belt.

  The high-angle belt 33 is disposed on the outer side in the tire radial direction of the carcass 2 and on the inner side in the tire radial direction of the cross belt 31. In the high-angle belt 33, the angle α4 in the extending direction with respect to the tire circumferential direction is 45 ° ≦ α4 ≦ 90 °, and the cords are arranged in the tire width direction. Further, the high-angle belt 33 has its own outer end in the tire width direction (end on the outer side in the tire width direction) disposed in the tire width direction range of the above-described width direction reinforcing belt portion 323.

  As described above, the carcass 2 is disposed on the outer surface in the tire radial direction and has a cord in which the angle α4 in the extending direction with respect to the tire circumferential direction is 45 ° ≦ α4 ≦ 90 °, and its outer end in the tire width direction is By further including a high-angle belt 33 disposed in the range of the width-direction reinforcing belt portion 323 in the tire width direction, the high-angle belt 33 cooperates with the belt portions 321, 322, and 323 to endure the belt layer 3. Can be improved.

  The protective belt 34 is disposed on the outermost side in the tire radial direction and on the outer side in the tire radial direction of the cross belt 32 disposed on the outer side in the tire radial direction. The protection belt 34 is arranged in the tire width direction with an angle α5 with respect to the tire circumferential direction in the same direction as the cord of the cross belt 32 and 10 ° ≦ α5 ≦ 30 °. Further, the protective belt 34 has its own outer end in the tire width direction disposed in the range of the width direction reinforcing belt portion 323 in the tire width direction.

  Thus, the angle α5 with respect to the tire circumferential direction is 10 ° ≦ α5 ≦ 30 ° in the same direction as the cross belt 32 disposed on the tire radial direction outer side of the cross belt 32 disposed on the tire radial direction outer side. The protective belt 34 further includes a protection belt 34 having a cord and having an outer end in the tire width direction disposed within a range of the width direction reinforcing belt portion 323 in the tire width direction, so that the protection belt 34 has the belt portions 321 and 322. , 323, the durability of the belt layer 3 can be further improved.

  In the pneumatic tire 1 configured as described above, the tire diameter of the carcass 2 is such that an angle α1 in the extending direction with respect to the tire circumferential direction has a cord of 10 ° ≦ α1 ≦ 30 °, and the cords cross each other. One of the two cross belts 31, 32 stacked on the outer side in the direction forms a cross belt portion 321 disposed in the center region of the tread 4, and is further arranged in parallel on both sides of the cross belt portion 321 in the tire width direction. A circumferential reinforcing belt portion 322 having a cord in which an angle α2 in the extending direction with respect to the tire circumferential direction is 0 ° ≦ α2 ≦ 5 °, and the tread 4 are arranged side by side on both sides of the circumferential reinforcing belt portion 322 in the tire width direction. And a width direction reinforcing belt portion 323 having a cord in which the angle α3 in the extending direction with respect to the tire circumferential direction is 10 ° ≦ α3 ≦ 90 ° and is formed of five belt portions in the tire width direction. And a composite belt of one layer.

  For this reason, the cross belt portion 321 and the cross belt 31 act as a low-angle cross belt layer with a cord having an angle α1 of 10 ° ≦ α1 ≦ 30 °, and the circumferential reinforcing belt portion 322 has 0 ° ≦ α2 ≦ 5 °. By acting as a tire circumferential reinforcing layer by the cord of the angle α2, the shape of the pneumatic tire 1 filled with air is held by the cross belt portion 321, the cross belt 31, and the circumferential reinforcing belt portion 322. Further, in the range where the tagging effect (pantograph effect) is large as in the center region of the tread 4, the cross belt portion 321 supports the internal pressure of the air filled in the pneumatic tire 1. Further, in the range between the center region and the shoulder region of the tread 4 and in the range in which the tagging effect is small and the diameter growth is likely to be large as in the vicinity of the circumferential main groove 41a on the outer side in the tire width direction of the tread 4, circumferential reinforcement The belt portion 322 supports the internal pressure of air. Further, in the shoulder region of the tread 4 and in the range where the burden of supporting the internal pressure of the air by the carcass 2 becomes large like the outer end portion of the belt layer 3 in the tire width direction, the angle α3 of 10 ° ≦ α3 ≦ 90 ° is satisfied. The cord causes the width direction reinforcing belt portion 323 to follow the pulling in the tire circumferential direction in the shoulder region to reduce the distortion of the belt layer 3 at the outer end in the tire width direction. As a result, the durability of the belt layer 3 can be improved. The width direction reinforcing belt portion 323 preferably has a cord having an angle α3 of 45 ° ≦ α3 ≦ 90 ° in order to follow pulling in the tire circumferential direction in the shoulder region.

  Moreover, since the cross belt portion 321, the circumferential reinforcing belt portion 322, and the width direction reinforcing belt portion 323 are configured as a single-layer composite belt, each of which is divided into functions, it is reinforced in addition to the cross belts 32 and 33. Therefore, the pneumatic tire 1 can be reduced in weight while improving the durability of the belt layer 3 without further increasing the number of belt layers.

  Further, since the composite belt is disposed on the outer side in the tire radial direction of the cross belt 31, particularly in the shoulder region of the tread 4, 10 ° ≦ α3 ≦ 90 ° (preferably 45 ° ≦ α3 ≦ 90 °). Since the width direction reinforcing belt portion 323 having the cord of the angle α3 is disposed on the outer side in the tire radial direction of the cross belt 31 that does not constitute a single-layer composite belt, the outer end portion of the cross belt 31 in the tire width direction (tire Prevent belt edge separation (near the outer edge in the width direction). As a result, the durability of the belt layer 3 can be further improved.

  In the range from the tire equatorial plane 50 to the tire width direction half width, the cross belt portion 321 has its own tire width direction dimension A with respect to the tire width direction dimension W of the carcass 2 0.4 ≦ A / W ≦ 0. 5, the circumferential reinforcing belt portion 322 has a tire width direction dimension B from the tire equatorial plane 50 to the outer end in the tire width direction of 0.6 ≦ B / W ≦ 0 with respect to the dimension W of the carcass 2. The width direction reinforcing belt portion 323 has a tire width direction dimension C from the outer end in the tire width direction of the circumferential direction reinforcing belt portion 322 to the outer width end of the tire width direction to the dimension W of the carcass 2. On the other hand, a range of 0.1 ≦ C / W is set. For this reason, each belt part 321,322,323 is arrange | positioned corresponding to a center area | region, a shoulder area | region, and the area | region between them, and since the tagging effect is fully exhibited, durability of the belt layer 3 can be improved more.

  FIG. 2 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention. An embodiment of the present invention will be described with reference to FIG. Here, the pneumatic tire 1 according to the embodiment described above is prototyped, and the performance test of the performance of the pneumatic tire 1 and the conventional pneumatic tire is performed to determine the durability and weight of the belt layer. The two items were conducted. In this performance test, a pneumatic tire having a tire size of 445 / 50R22.5 was mounted on a rim having a size of 22.5 × 14.00, and the air pressure was set to 830 kPa. For durability, the pneumatic tire was mounted on an indoor drum tester, and the distance traveled until the pneumatic tire broke at a speed of 45 km / h and a load of 63.50 kN was measured. The index indicates that the larger the index, the better the durability. Further, the weight is indicated by an index with the measured result of the conventional example as 100%, and the smaller the index, the better the weight reduction.

  In this example, as shown in FIG. 2, one type as a conventional example compared with the present invention and six types as examples of the present invention are tested by the above method. In the pneumatic tires shown in Examples 1 to 6, the high-angle belt 33, the cross belt 31, the cross belt 32 (cross belt portion 321, circumferential direction reinforcement) are sequentially arranged from the tire radial direction outer side surface of the carcass 2 having a tire width direction dimension of 430 mm. A belt layer 3 is formed by laminating four layers of a belt portion 322, a width direction reinforcing belt portion 323), and a protective belt 34. On the other hand, in the pneumatic tire shown in the conventional example, a high-angle belt, a cross belt, a circumferential reinforcing belt portion, and a cross belt (outer in the tire radial direction) are sequentially arranged from the outer side in the tire radial direction of the carcass having a tire width dimension of 430 mm. , And the outermost protective belt in the radial direction of the tire constitutes five belt layers. That is, while the pneumatic tires of Examples 1 to 6 are provided with the cross belt portion 321, the circumferential reinforcing belt portion 322, and the width direction reinforcing belt portion 323 with respect to the conventional pneumatic tire, The fifth belt is not provided.

  As apparent from FIG. 2, the pneumatic tires shown in “Examples 1 to 6” improve the durability of the belt layer 3 and reduce the weight.

  As described above, the pneumatic tire according to the present invention is suitable for achieving both improvement in durability and weight reduction of the belt layer.

It is a meridional sectional view showing a pneumatic tire according to an embodiment of the present invention. It is a graph which shows the result of the performance test of the pneumatic tire concerning the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Carcass 3 Belt layer 31 Cross belt 32 Cross belt 321 Cross belt part 322 Circumferential reinforcement belt part 323 Width direction reinforcement belt part 33 High angle belt 34 Protection belt 4 Tread 41 Tread surface 41a Circumferential main groove 50 Tire Equatorial plane CL Center crown A Dimension in the tire width direction of the intersecting belt B B Width in the tire width direction from the tire equator plane to the end in the tire width direction of the circumferential reinforcing belt portion C Width direction from the outer end in the tire width direction of the circumferential reinforcing belt portion Tire width direction dimension to the outer end of the reinforcing belt part in the tire width direction Ni cord strength W Carcass tire width direction dimension Wmax Maximum tire width direction dimension of pneumatic tire

Claims (10)

At least two intersecting belts that are laminated on the outer side in the tire radial direction of the carcass so that the angle α1 in the extending direction with respect to the tire circumferential direction has a cord of 10 ° ≦ α1 ≦ 30 ° and the cord intersects each other. In a pneumatic tire provided with a belt layer,
A cross belt portion disposed in the center area of the tread as one of the cross belts;
A circumferential reinforcing belt portion having cords arranged side by side on both sides in the tire width direction of the intersecting belt portion and having an angle α2 in the extending direction relative to the tire circumferential direction of 0 ° ≦ α2 ≦ 5 °;
The circumferential reinforcing belt portion has cords arranged side by side in the tire width direction and disposed in the shoulder region of the tread so that the angle α3 in the extending direction with respect to the tire circumferential direction is 10 ° ≦ α3 ≦ 90 °. A pneumatic tire comprising a one-layer composite belt comprising a width direction reinforcing belt portion.   2. The pneumatic tire according to claim 1, wherein the one-layer composite belt is disposed on the outer side in the tire radial direction of the cross belt that does not constitute the composite belt.   The pneumatic tire according to claim 1 or 2, wherein the width direction reinforcing belt portion has a cord in which an angle α3 in an extending direction with respect to a tire circumferential direction is 45 ° ≦ α3 ≦ 90 °. In the range from the tire equator to the half width in the tire width direction,
The cross belt portion is set such that its own tire width direction dimension A is 0.4 ≦ A / W ≦ 0.5 with respect to the carcass tire width direction dimension W.
In the circumferential reinforcing belt portion, a tire width direction dimension B from the tire equatorial plane to the outer end in the tire width direction is set in a range of 0.6 ≦ B / W ≦ 0.75 with respect to the carcass dimension W. ,
In the width direction reinforcing belt portion, a tire width direction dimension C from the outer end in the tire width direction of the circumferential direction reinforcing belt portion to an outer end in the tire width direction of the own circumferential direction is 0.1 ≦ C / It is set to the range of W. The pneumatic tire according to any one of claims 1 to 3 characterized by things.   When the sum of the cord strengths in the tire circumferential direction of the circumferential reinforcing belt portion and each of the cross belts is ΣN, the cord strength Ni of the circumferential reinforcing belt portion is 0.3 ≦ Ni / ΣN ≦ 0.5 The pneumatic tire according to any one of claims 1 to 4, characterized by comprising:   The width direction reinforcing belt portion has a cord larger than the cord diameter of the cross belt portion, and the number of cord ends in a predetermined length in the cord arrangement direction is equal to or less than the number of cord ends of the cross belt portion. The pneumatic tire according to any one of claims 1 to 5, wherein:   The carcass is disposed on the outer surface in the tire radial direction and has a cord in which an angle α4 in the extending direction with respect to the tire circumferential direction is 45 ° ≦ α4 ≦ 90 °, and its outer end in the tire width direction is the width direction reinforcement The pneumatic tire according to claim 1, further comprising a high-angle belt disposed in a range of the belt portion in the tire width direction.   The cross belt disposed on the outer side in the tire radial direction has a cord in which the angle α5 with respect to the tire circumferential direction in the same direction as the cord of the cross belt is 10 ° ≦ α5 ≦ 30 °. And a protective belt disposed at an outer end of the tire width direction in a range of the width direction reinforcing belt portion in the tire width direction. Pneumatic tire.   The pneumatic tire according to claim 1, which has a maximum tire width direction dimension of 300 mm or more.   The pneumatic tire according to any one of claims 1 to 9, wherein the pneumatic tire has a flatness ratio of 70% or less.

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