JP4984633B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire in which a mesh-like protrusion is provided on the inner surface of a buttress portion, and more specifically, it is possible to reduce road noise without causing an excessive increase in mass or an adverse effect on tire performance. Related to pneumatic tires.

  In recent years, with the upgrading and quietness of automobiles, it is required to reduce road noise caused by vibrations during traveling being transmitted to the passenger compartment. In particular, road noise in a frequency band of 250 Hz to 400 Hz is generated by a vibration mode in which a portion of the belt end position of the pneumatic tire and a portion of the tire maximum width position become nodes and the buttress portion between them becomes an antinode. For this reason, conventionally, it has been proposed to reduce the road noise by suppressing the occurrence of vibration by increasing the rigidity of the buttress portion that becomes the antinode of vibration. For example, expanding the belt width or adding a belt edge cover as a method to increase the rigidity of the buttress part, but these methods not only increase the tire mass but also improve tire performance such as steering stability. The impact on will be greater. As another method, it has been proposed to provide a protrusion extending in the tire circumferential direction on the tire inner surface of the buttress portion, and to increase the rigidity of the buttress portion by the protrusion to reduce road noise (for example, Patent Document 1 and Patent Document). 2).

However, when the protrusion extending in the tire circumferential direction is provided on the tire inner surface of the buttress portion, the effect of suppressing the vibration of the tire is not necessarily sufficient, and in order to obtain the effect of reducing road noise, it is necessary to increase the volume of the protrusion. After all, the current situation is that an increase in tire mass and an adverse effect on tire performance cannot be avoided.
JP-A-6-206402 Japanese Patent Laid-Open No. 2001-1726

  An object of the present invention is to provide a pneumatic tire capable of reducing road noise without causing an excessive increase in mass and an adverse effect on tire performance.

In order to achieve the above object, the pneumatic tire of the present invention has a belt layer embedded in the tread portion in the region between the center position in the width direction and a position half the belt half width and the tire maximum width position. A protrusion that protrudes from the inner surface of the tire and extends in a mesh shape is formed, and the end of the protrusion on the tread center side is between a position that is 2/3 times the belt half width from the center position in the width direction of the belt layer and the belt end position. The bead side end of the protrusion is disposed between the tire maximum width position and a position 0.2 times the tire cross-section height from the tire maximum width position, and the mesh interval of the protrusion is set to the tire. In the region where the circumference is uneven and the groove area of the tread portion is relatively large, the mesh spacing of the protrusions is relatively narrow .

  In the present invention, the belt layer extends in a mesh shape while projecting from the inner surface of the tire in a buttress portion defined by a region between the center position in the width direction of the belt layer and a position that is 2/3 times the belt half width and the maximum tire width position. Protrusions that form. In other words, road noise in the frequency band of 250 Hz to 400 Hz is generated by a vibration mode in which the portion of the belt end position of the pneumatic tire and the portion of the tire maximum width position become nodes and the buttress portion between them becomes an antinode. In view of this, road noise can be effectively reduced with a minimum number of reinforcing members by providing a mesh-like protrusion on the buttress portion. Therefore, it is possible to reduce road noise without causing an excessive increase in mass and an adverse effect on tire performance as compared with the conventional method. Further, since the net-like projections have a structure in which a plurality of types of rib components having different extending directions intersect each other, the durability of itself is good.

  In the present invention, the protrusions can be formed of rib components in two directions intersecting with each other, and a rib structure including a plurality of void portions forming a quadrangle in a plan view can be formed by these rib components. Further, the protrusions may be formed of rib components in three directions intersecting with each other, and a honeycomb structure including a plurality of void portions forming a hexagon in plan view may be formed by these rib components. In particular, in the case of a honeycomb structure, the rib components are firmly bound to increase the rigidity of the protrusions, so that road noise can be effectively reduced.

  Also, in order to obtain an effect of reducing road noise while minimizing the increase in mass, the height from the tire inner surface of the portion with the largest protrusion of the rib component constituting the protrusion is the tire thickness at the tire maximum width position. It is preferable that the width of the portion of the rib component constituting the protrusion that contacts the tire inner surface is 0.25 to 0.4 times the tire thickness at the tire maximum width position.

As described above , the mesh area of the protrusions is made uneven on the tire circumference, and the mesh area of the protrusions is relatively narrow at the portion where the groove area of the tread portion is relatively large. It is possible to cancel the mass imbalance caused by the tire and improve the tire uniformity.

  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. Two carcass layers 4 are mounted between the pair of left and right bead portions 3 and 3, and end portions of the carcass layers 4 are folded around the bead core 5 from the inside to the outside of the tire. On the outer peripheral side of the carcass layer 4 in the tread portion 1, two belt layers 6 are disposed over the entire circumference of the tire. 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. The belt cover layer 7 includes a reinforcing cord oriented in the tire circumferential direction, and the reinforcing cord is continuously wound in the tire circumferential direction.

  In the pneumatic tire, a region between a position P1 that is 2/3 times the belt half width Wb and a tire maximum width position P2 at which the tire cross-sectional width W is maximum from the center position C in the width direction of the belt layer 4 having the maximum width. X is formed with a protrusion 11 that protrudes from the tire inner surface and extends in a mesh shape.

  FIG. 2 shows an example of a mesh-like projection formed on the inner surface of the tire, and FIG. 3 shows the projection of FIG. 2 in an enlarged manner. 2 and 3, the mesh-shaped protrusion 11 is composed of rib components 11x and 11y in two directions intersecting each other, and these rib components 11x and 11y form a quadrangle (square, rectangular or parallelogram) in plan view. A grid structure including a plurality of gap portions 12 is formed. In this case, while the increase in mass is suppressed by the presence of the plurality of gap portions 12, the rib components 11x and 11y in the two directions are tightly bound to increase the rigidity of the protrusions 11, so that the effect of reducing road noise is sufficient. can get.

  FIG. 4 shows another example of a mesh-like projection formed on the inner surface of the tire, and FIG. 5 shows the projection of FIG. 4 in an enlarged manner. 4 and 5, the mesh-shaped protrusion 11 is composed of three-direction rib components 11x, 11y, and 11z that intersect with each other, and a plurality of gaps that form a hexagon in plan view by these rib components 11x, 11y, and 11z. A honeycomb structure including the portion 12 is formed. In this case, while the increase in mass is suppressed by the presence of the plurality of gap portions 12, the rib components 11x, 11y, and 11z in the three directions are firmly bound to increase the rigidity of the protrusions 11, so that an effect of reducing road noise is achieved. growing.

  The protrusions 11 are desirably formed integrally on the tire inner surface during tire vulcanization, but may be bonded to the tire inner surface using an adhesive or the like after vulcanization. If a core or the like made of a rigid body is used instead of the rubber bladder as the means for pressurizing the tire inner surface during tire vulcanization, the formation of the protrusions 11 is easy. As a material for the protrusion 11, hard rubber, plastic resin, or the like can be used in addition to the same type of rubber as the rubber on the inner surface of the tire. When the same type of rubber or hard rubber as the rubber on the inner surface of the tire is used, the projection 11 can be molded during vulcanization, so that a sticking step after vulcanization is not required, and there is a concern that the adhesive portion of the projection 11 will peel off. Disappear.

  As shown in FIG. 1, the end 11a of the protrusion 11 on the tread center side is disposed between a position P1 that is 2/3 times the belt half width Wb from the center position C in the width direction of the belt layer 6 and the belt end position P3. ing. Further, the bead side end 11b of the protrusion 11 is disposed between the tire maximum width position P2 and a position P4 that is 0.2 times the tire cross-section height H from the tire maximum width position P2.

  Thus, by forming the protrusion 11 which protrudes from the tire inner surface and extends in a mesh shape in the buttress portion defined by the region X, the belt end position P3 portion and the tire maximum width position P2 of the pneumatic tire are formed. The vibration with which the portion becomes a node and the buttress portion in between becomes a belly can be suppressed with a minimum reinforcing member. Therefore, road noise in a frequency band of 250 Hz to 400 Hz can be reduced without causing an excessive increase in mass or an adverse effect on tire performance.

  Here, when the end portion 11a of the protrusion 11 is positioned on the tread center side from the position P1 that is 2/3 times the belt half width Wb from the center position C in the width direction of the belt layer 6, the mass of the road noise reduction effect can be obtained. Rolling resistance deteriorates due to the increase. Further, when the end portion 11a of the protrusion 11 is located on the bead side with respect to the belt end position P3, the effect of reducing road noise becomes insufficient. On the other hand, when the end portion 11b of the protrusion 11 is positioned on the bead side with respect to the tire maximum width position P2, the rolling resistance is deteriorated due to an increase in mass although an effect of reducing road noise is obtained. If the end 11b of the protrusion 11 is located on the tread center side from the position P4 that is 0.2 times the tire cross-section height H from the tire maximum width position P2, the effect of reducing road noise becomes insufficient.

  6 is an enlarged view of the main part of FIG. 1, and FIG. 7 is a cross-sectional view taken along line AA of FIG. As shown in FIG. 6, the protrusion 11 gradually protrudes from the tire inner surface toward both ends in the width direction toward the center. Of course, the protrusion amount of the protrusion 11 may be uniform over the entire width. As shown in FIG. 7, the rib component of the protrusion 11 has a cross-sectional shape in which the apex side has an arc shape. The cross-sectional shape of the rib component of the protrusion 11 is not particularly limited, and the same effect can be obtained in the case of a trapezoid or the like.

  The height h from the tire inner surface of the portion with the largest protrusion amount of the rib component constituting the protrusion 11 is preferably 0.25 to 0.4 times the tire thickness T at the tire maximum width position P2. When the height h is less than 0.25 times the tire thickness T at the tire maximum width position P2, the effect of reducing road noise becomes insufficient. Further, when the height h exceeds 0.4 times the tire thickness T at the tire maximum width position P2, the rolling resistance is deteriorated due to the increase in mass, and further, the rib components are deformed due to the deformation of the protrusion 11 accompanying the tire rolling. It becomes easy to produce a damage in the united part.

  The width w of the portion of the rib component constituting the protrusion 11 that contacts the tire inner surface is preferably 0.25 to 0.4 times the tire thickness T at the tire maximum width position P2. If the width w is less than 0.25 times the tire thickness T at the tire maximum width position P2, the effect of reducing road noise becomes insufficient. Further, if the width w exceeds 0.4 times the tire thickness T at the tire maximum width position P2, the rolling resistance is deteriorated due to the increase in mass, and further, the rib components are bound together by deformation of the protrusion 11 accompanying the tire rolling. It becomes easy to produce damage to the part which has done.

Grid spacing P of the projections 11 (see FIGS. 3 and 5) is made uneven on tires laps in consideration of the variation in the groove area of the tread portion 1. In other words, in a portion where the groove area of the tread portion 1 is relatively large, the mesh spacing P of the protrusions 11 is made relatively narrow, thereby canceling the mass imbalance caused by the groove area variation and improving the tire uniformity. can do. In the present invention, the protrusions 11 are used not only as vibration suppression means but also as uniformity improvement means . Note that the mesh interval P of the protrusion 11 means the interval between the vertex positions of the opposing rib components, and when there is no vertex, it means the interval between the center positions in the width direction of the opposing rib components.

  In the pneumatic tire of tire size 215 / 60R16 95H, tires of Conventional Examples 1-2, Examples 1-6, and Comparative Examples 1-3, in which the tire inner surface shape was varied, were produced.

  The tire of Conventional Example 1 has no protrusion on the inner surface of the buttress portion. The tire of Conventional Example 2 has a belt width increased by 10 mm compared to Conventional Example 1 without providing protrusions on the inner surface of the buttress portion.

  In Examples 1 to 6 and Comparative Examples 1 to 3, protrusions are provided on the tire inner surface of the buttress portion, and the positions and dimensions thereof are set as shown in Table 1. In addition, the position of the end portion on the tread center side of the protrusion is indicated by a distance from the center position C in the belt width direction using the belt half width Wb as an index, and the position of the end portion on the bead side of the protrusion is indicated by the tire cross-section height H. The distance from the tire maximum width position P2 is shown, and the height h and width w of the protrusion are shown as a ratio to the tire thickness T at the tire maximum width position.

  For these test tires, road noise, steering stability, and rolling resistance were evaluated by the following test methods, and the results are also shown in Table 1.

Road noise:
The test tire was assembled on a wheel having a rim size of 16 × 7 JJ, adjusted to an internal pressure of 200 kPa, and mounted on a test vehicle (front wheel drive vehicle) having a displacement of 2000 cc. Then, load conditions equivalent to two passengers are set in a test vehicle equipped with a measuring instrument, a microphone is installed at the driver's seat window side position, and a road noise with a frequency of 315 Hz generated when traveling at a speed of 60 km on the test course [ dB (A)] was measured.

Steering stability:
The test tire was assembled on a wheel having a rim size of 16 × 7 JJ, adjusted to an internal pressure of 200 kPa, and mounted on a test vehicle (front wheel drive vehicle) having a displacement of 2000 cc. Then, a sensory test was conducted by a test driver for handling stability including lane changeability and turning ability, and the handling stability was scored by a 10-point method. The larger this evaluation point, the better the steering stability.

Rolling resistance:
The test tire was assembled on a wheel having a rim size of 16 × 7 JJ, adjusted to an internal pressure of 200 kPa and mounted on a rolling resistance tester, and the rolling resistance was measured at a speed of 80 km / h. The evaluation results are shown as an index with the conventional example 1 as 100, using the reciprocal of the measured value. It means that rolling resistance is so small that this index value is large.

  As shown in Table 1, the tires of Examples 1 to 3 were able to effectively reduce road noise while maintaining tire performance equivalent to that of Conventional Example 1. In the tire of Conventional Example 2, although the reduction effect of road noise was slightly recognized, the steering stability was lowered. In the tires of Comparative Examples 1 and 2, the road noise reduction effect was insufficient. In the tire of Comparative Example 3, although the reduction effect of road noise was recognized, the rolling resistance was deteriorated.

It is a meridian half section view showing a pneumatic tire according to an embodiment of the present invention. It is a perspective sectional view showing an example of a mesh-like projection formed in the tire inner surface. It is a top view which expands and shows the protrusion of FIG. It is a perspective sectional view showing other examples of mesh-like projections formed in the tire inner surface. It is a top view which expands and shows the protrusion of FIG. It is a principal part enlarged view of FIG. It is AA arrow sectional drawing of FIG.

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 11a End part of protrusion tread center side 11b End part of protrusion bead side 11x, 11y, 11z Rib component 12 Air gap portion

Claims (4)

Protrusions that extend from the inner surface of the tire and extend in a mesh shape are formed in a region between the center position in the width direction of the belt layer embedded in the tread portion and a position that is 2/3 times the belt half width and the maximum tire width position. The end of the protrusion on the tread center side is disposed between a position that is 2/3 times the belt half width from the center position in the width direction of the belt layer and the belt end position. It is arranged between a large position and a position 0.2 times the tire cross-section height from the maximum tire width position, and the mesh spacing of the projections is made uneven on the tire circumference, so that the groove area of the tread portion is relatively A pneumatic tire in which the mesh spacing of the protrusions is relatively narrow at a particularly large portion .   2. The pneumatic tire according to claim 1, wherein the protrusion includes a rib component in two directions intersecting each other, and a rib structure including a plurality of void portions forming a quadrangle in a plan view is formed by the rib component.   2. The pneumatic tire according to claim 1, wherein the protrusion is configured by rib components in three directions intersecting each other, and a honeycomb structure including a plurality of void portions having a hexagonal shape in plan view is formed by the rib components.   The height from the tire inner surface of the portion having the largest protrusion amount of the rib component constituting the protrusion is set to 0.25 to 0.4 times the tire thickness at the tire maximum width position, and the rib component constituting the protrusion The pneumatic tire according to any one of claims 1 to 3, wherein a width of a portion in contact with the tire inner surface is set to 0.25 to 0.4 times a tire thickness at a tire maximum width position.

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