JP2006248317A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire achieving light weight while ensuring rigidity of a side wall part and achieving enhancement of durability. <P>SOLUTION: In the pneumatic tire provided with a carcass layer 4 in which a cord angle relative to a tire circumferential direction is smaller than 90°, a plurality of band-like projection parts 11 extending while inclined in an opposite direction to a cord inclination direction of the most near carcass layer 4 are provided on a surface of the side wall part 2 extending between a tread part 1 and a bead part 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire in which the rigidity of the sidewall portion is optimized, and more specifically, a pneumatic tire that can be reduced in weight while ensuring the rigidity of the sidewall portion, and can improve durability. About.

  Conventionally, in a pneumatic tire, in order to receive a high load at the time of braking or cornering, a plurality of carcass layers are laminated, a cord angle of the carcass layer with respect to the tire circumferential direction is made smaller than 90 °, and a cord is corded between the layers. A so-called half radial structure that intersects each other has been proposed (see, for example, Patent Document 1). Further, when higher rigidity is required, the turn-up portion of the carcass layer is also extended below the shoulder portion and the belt layer.

However, when the rigidity of the sidewall portion is ensured based on the carcass layer, there is a problem that the tire mass increases due to a significant increase in the amount of the carcass material used. Further, as an adverse effect of an increase in tire mass, vehicle motion performance is reduced due to an increase in unsprung mass, which is a factor that reduces the effect obtained by increasing the rigidity of the sidewall portion. Furthermore, if a plurality of carcass layers are stacked or the turn-up portion of the carcass layer is extended under the shoulder portion or the belt layer, the carcass layer stores heat, and the heat storage causes a problem that durability decreases. Yes.
JP-A-1-321939

  An object of the present invention is to provide a pneumatic tire capable of reducing the weight while ensuring the rigidity of the sidewall portion and improving the durability.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a sidewall extending between a tread portion and a bead portion in a pneumatic tire including a carcass layer having a cord angle with respect to a tire circumferential direction of less than 90 °. A plurality of strip-shaped projections extending while being inclined in a direction opposite to the cord inclination direction of the nearest carcass layer are provided on the surface of the portion.

  In the present invention, in a pneumatic tire having a so-called half radial structure, a plurality of tires extending while being inclined in a direction opposite to the cord inclination direction of the nearest carcass layer on the surface (inner surface or outer surface or both surfaces) of the sidewall portion. Since the band-shaped protrusion is provided, the amount of the carcass material used can be reduced while ensuring the rigidity of the sidewall. As a result, the weight of the pneumatic tire is reduced, and the vehicle motion performance can be improved by reducing the unsprung mass. Moreover, by reducing the amount of the carcass material used, heat storage in the carcass layer can be avoided and the durability of the pneumatic tire can be improved.

  In the present invention, in order to ensure the rigidity of the sidewall portion, the angle of the protrusion with respect to the tire circumferential direction is preferably 45 ° to 85 ° at the portion closest to the belt layer. The width of the protrusions is preferably 2 mm or more and 10 mm or less, the distance between the protrusions is 3 mm or more and 15 mm or less, and the height of the protrusions is preferably 2 mm or more and 8 mm or less. The width of the protrusion may be partially changed depending on the required rigidity.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a pneumatic tire according to an embodiment of the present invention. In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. A carcass layer 4 is mounted between the pair of left and right bead portions 3 and 3, and an end portion of the carcass layer 4 is folded around the bead core 5 from the inside to the outside of the tire. The carcass layer 4 includes a plurality of aligned carcass cords, and these carcass cords are inclined with respect to the tire radial direction. The cord angle with respect to the tire circumferential direction measured at the center position in the tread width direction of the carcass layer 4 is smaller than 90 °, and more preferably set in a range of 70 ° to 80 °. On the outer peripheral side of the carcass layer 4 in the tread portion 1, a belt layer 6 is disposed over the entire tire circumference. These belt layers 6 include reinforcing cords that are inclined with respect to the tire circumferential direction, and are arranged such that the reinforcing cords cross each other between the layers. Further, a belt cover layer 7 is disposed on the outer peripheral side of the belt layer 6.

  In the pneumatic tire, a plurality of belt-like protrusions 11 extending while inclining with respect to the tire radial direction are formed on the inner surface of the sidewall portion 2 extending between the tread portion 1 and the bead portion 3. Has been. More specifically, the protrusion 11 is inclined in the direction opposite to the cord inclination direction of the nearest carcass layer 4. These protrusions 11 are preferably present at least in the range from the vicinity of the end of the belt layer 6 to the tire maximum width position in order to effectively reinforce the bending region of the sidewall portion 2. The belt layer 6 may extend from the vicinity of the end portion to the bead portion 3.

  In the pneumatic tire described above, a half radial structure is adopted, and at the same time, a plurality of belt-like protrusions 11 extending on the inner surface of the sidewall portion 2 while being inclined in a direction opposite to the cord inclination direction of the nearest carcass layer 4 are provided. Since it is provided, the usage amount of the carcass material can be reduced while ensuring the rigidity of the sidewall portion 2. Thereby, a pneumatic tire can be reduced in weight. And by reducing the usage-amount of carcass material, the heat storage in the carcass layer 4 can be avoided and the durability of a pneumatic tire can be improved.

  Here, the angle of the protrusion 11 with respect to the tire circumferential direction is preferably 45 ° to 85 ° at a portion closest to the belt layer. If this angle deviates from the above range, the reinforcing effect due to the intersection with the carcass cord becomes insufficient. When the angle of the protrusion 11 with respect to the tire circumferential direction is 60 ° to 80 °, a more preferable effect is obtained.

  The width of the protrusion 11 is preferably 2 mm or more and 10 mm or less. If the width of the protrusion 11 is less than 2 mm, the effect of increasing the rigidity in the tire circumferential direction is insufficient, and conversely if it exceeds 10 mm, the tire mass increases. A preferred width is 4 mm to 7 mm. Further, the width of the protrusion 11 may be partially changed according to the required rigidity. For example, the rigidity balance may be optimized by partially widening the width of the protrusion 11 in the vicinity of the tire maximum width position where the greatest force is applied. However, the ratio of the maximum width to the minimum width is desirably 2.0 or less.

  The interval between the protrusions 11 is preferably 3 mm or more and 15 mm or less. If the distance between the protrusions 11 is less than 3 mm, the adjacent protrusions 11 may interfere with each other when the deformation of the sidewall portion 2 is large, causing a sudden change in rigidity (abrupt behavior change). If it exceeds, the effect of increasing the rigidity in the tire circumferential direction becomes insufficient. A preferable interval is 5 mm to 8 mm. Moreover, you may change the space | interval of the projection part 11 partially according to the required rigidity. For example, the rigidity balance may be optimized by partially narrowing the interval between the protrusions 11 in the vicinity of the tire maximum width position where the greatest force is applied.

  The height of the protrusion 11 is preferably 2 mm or more and 8 mm or less. If the height of the protrusion 11 is less than 2 mm, the effect of increasing the rigidity in the tire circumferential direction becomes insufficient. Conversely, if the height exceeds 8 mm, no further effect is obtained, and only an increase in weight is caused. A preferred height is 4 mm to 6 mm.

  FIG. 2 shows a pneumatic tire according to another embodiment of the present invention. As shown in FIG. 2, in this embodiment, a plurality of belt-like protrusions 11 extending on the outer surface of the sidewall portion 2 while being inclined in a direction opposite to the cord inclination direction of the nearest carcass layer 4 are formed. ing. As described above, the protrusion 11 may be provided on the outer surface of the sidewall 2.

  In the embodiment described above, the case where the band-like protrusions are provided on the inner surface or the outer surface of the sidewall part has been described. However, in the present invention, the band-like protrusions may be provided on both surfaces of the sidewall part.

  In the embodiment described above, the pneumatic tire including one carcass layer has been described. However, the present invention can also be applied to a pneumatic tire including a plurality of carcass layers. When providing a plurality of carcass layers, it is desirable to arrange the carcass cords so as to cross each other. In any case, it is necessary that the inclination direction of the band-shaped protrusions intersects the cord inclination direction of the nearest carcass layer.

  In the pneumatic tire of tire size 255 / 40R17 94W, the tires of Conventional Example 1 and Examples 1 to 3 in which a half radial structure was adopted and the shape of the inner surface of the sidewall portion were varied were produced.

  The tire of Conventional Example 1 includes two carcass layers, and the turn-up end position of the carcass layer is disposed near the belt end, and the inner surface of the sidewall portion is substantially smooth (see FIG. 3). The tire of Example 1 includes two carcass layers, and the turn-up end position of the carcass layer is arranged near the upper end of the filler, and the direction opposite to the cord inclination direction of the carcass layer closest to the inner surface of the sidewall portion Are provided with a plurality of belt-like protrusions inclined at an angle of 80 ° with respect to the tire circumferential direction. The tire of Example 2 includes two carcass layers, and the turn-up end position of the carcass layer is arranged near the upper end of the filler, and the direction opposite to the cord inclination direction of the carcass layer closest to the inner surface of the sidewall portion Are provided with a plurality of belt-like protrusions inclined at an angle of 60 ° with respect to the tire circumferential direction. The tire of Example 3 includes one carcass layer, the turn-up end position of the carcass layer is disposed near the belt end, and the direction opposite to the cord inclination direction of the carcass layer closest to the inner surface of the sidewall portion Are provided with a plurality of belt-like protrusions inclined at an angle of 70 ° with respect to the tire circumferential direction. The width of the protrusions was 6 mm, the distance between the protrusions was 9 mm, and the height of the protrusions was 5 mm.

  About these test tires, tire mass, durability, steering stability, running time, and circumferential rigidity were evaluated by the following test methods, and the results are shown in Table 1.

Tire mass:
The mass of the test tire was measured. The evaluation results are shown as an index with Conventional Example 1 as 100. It means that it is so light that this index value is small.

durability:
The test tire is assembled to a wheel with a rim size of 17 × 9.5 JJ, the air pressure is set to 200 kPa, and after performing the durability test specified in JIS D4230 using a drum tester, the load is continuously increased by 10% every 4 hours. The test was continued while increasing the distance traveled until the tire failed. The evaluation results are shown as an index with Conventional Example 1 as 100. The larger the index value, the better the durability.

Steering stability:
The test tire is mounted on a wheel with a rim size of 17 x 9.5 JJ, mounted on a four-wheel drive vehicle equipped with a motor with a supercharger with a displacement of 2000 cc, and the air pressure after warm-up is 200 kPa. The sensory evaluation by was carried out. The evaluation results are shown as an index with Conventional Example 1 as 100. The larger the index value, the better the steering stability.

Travel time:
The test tire is mounted on a wheel with a rim size of 17 x 9.5 JJ, mounted on a four-wheel drive vehicle equipped with a motor with a supercharger with a displacement of 2000 cc, and the air pressure after warm-up is 200 kPa. The section travel was carried out and the time required for the section travel was measured. The evaluation results are shown as an index with the conventional example 1 as 100, using the reciprocal of the measured value. The larger the index value, the shorter the traveling time and the better the traveling performance.

Circumferential rigidity:
Using a side stiffness tester, the stiffness in the tire circumferential direction was measured under the conditions of a rim size of 17 × 9.5 JJ and an air pressure of 200 kPa. The evaluation results are shown as an index with Conventional Example 1 as 100. A larger index value means higher circumferential rigidity.

  As shown in Table 1, the tires of Examples 1 to 3 had good evaluation results of tire mass, durability, steering stability, running time, and circumferential rigidity in comparison with Conventional Example 1.

  Next, tires of Examples 4 to 8 in which a half radial structure was adopted in the pneumatic tire having a tire size of 255 / 40R17 94W and the inner surface shapes of the sidewall portions were varied were produced. The tires of Examples 4 to 8 include two carcass layers, the turnup end position of the carcass layer is disposed near the upper end of the filler, and the direction of the cord inclination of the carcass layer closest to the inner surface of the sidewall portion. A plurality of belt-like projections inclined in opposite directions are provided, and the angle with respect to the tire circumferential direction is 60 °, and the width of the projections, the interval between the projections, and the height of the projections are varied.

For these test tires, the circumferential rigidity was evaluated by the test method described above, and the results are shown in Table 2. The evaluation result of the circumferential rigidity is shown by an index with the conventional example 1 as 100.

  As shown in Table 2, the tires of Examples 4 to 8 had good evaluation results of peripheral rigidity in comparison with Conventional Example 1.

1 is a perspective cross-sectional view showing a pneumatic tire according to an embodiment of the present invention with a part cut away. FIG. 5 is a perspective sectional view showing a pneumatic tire according to another embodiment of the present invention with a part cut away. It is a perspective sectional view showing a conventional pneumatic tire with a part cut away.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Belt layer 7 Belt cover layer 11 Protrusion part

Claims (4)

In a pneumatic tire having a carcass layer with a cord angle with respect to the tire circumferential direction smaller than 90 °, the cord inclination direction of the carcass layer closest to the surface of the sidewall portion extending between the tread portion and the bead portion is A pneumatic tire provided with a plurality of belt-like protrusions extending while inclining in the opposite direction. The pneumatic tire according to claim 1, wherein an angle of the protrusion with respect to the tire circumferential direction is set to 45 ° to 85 ° at a portion closest to the belt layer. The pneumatic tire according to claim 1 or 2, wherein a width of the protrusions is 2 mm or more and 10 mm or less, an interval between the protrusions is 3 mm or more and 15 mm or less, and a height of the protrusions is 2 mm or more and 8 mm or less. . The pneumatic tire according to any one of claims 1 to 3, wherein a width of the protruding portion is partially changed.

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