JP4984614B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire provided with a protrusion on the inner surface of a buttress portion, and more specifically, air that can reduce road noise without causing an excessive increase in mass or an adverse effect on tire performance. Related to 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 plurality of ridges extending in a range of for the radial -30 ° ~ + 30 ° and formed at intervals in the tire circumferential direction while protruding from the inner surface of the tire, the belt layer one end of said protrusion 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 and the belt end position, and the other end of the protrusion is positioned at the tire maximum width position and the tire maximum width position. The width of the portion contacting the inner surface of the tire is set to 3 mm to 10 mm, and the interval between the protrusions in the tire circumferential direction is made uneven on the tire circumference. In the region where the groove area of the tread portion is relatively large, It is characterized by a relatively large number of ridges .

  In the present invention, the belt layer extends in the radial direction while projecting from the inner surface of the tire to a buttress portion defined by a region between a position that is 2/3 times the belt half width and the tire maximum width position from the center position in the width direction of the belt layer. A plurality of protrusions to be formed are formed at intervals in the tire circumferential direction. 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 protrusions extending in the radial direction 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.

In the present invention, the ridge extends in the radial direction. However, as described above, since the extension direction is in the range of −30 ° to + 30 ° with respect to the radial direction , road noise is effectively reduced. Can be reduced.

Further, in order to obtain the effect of reducing road noise while minimizing the increase in mass, the height from the tire inner surface on the most protruding amount large portion of ridge is preferably set to the 2mm or more. For the same reason, it is preferable that the interval between the protrusions in the tire circumferential direction is 20 mm to 30 mm.

As described above, the distance in the tire circumferential direction of the ridges and unevenly on the circumference of the tire, since the groove area is relatively large portion of the tread portion is relatively large, the number of ridges, It is possible to cancel the mass imbalance caused by the change in the groove area and improve the tire uniformity.

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

  1 and 2 show 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. In X, a plurality of ridges 11 projecting from the tire inner surface and extending in the radial direction are formed at arbitrary intervals in the tire circumferential direction (see FIG. 2). As used herein, the radial direction means the tire meridian direction. The ridges 11 are desirably formed integrally on the inner surface of the tire during vulcanization of the tire, but may be bonded to the inner surface of the tire after vulcanization using an adhesive or the like.

  The end portion 11a on the tread center side of the protrusion 11 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. 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, the belt of a pneumatic tire is formed on the buttress portion defined by the region X by forming a plurality of ridges 11 projecting from the tire inner surface and extending in the radial direction at intervals in the tire circumferential direction. The end position P3 portion and the tire maximum width position P2 portion become nodes, and vibrations in which the buttress portion is an antinode 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 located on the tread center side from the position P1 which is 2/3 times the belt half width Wb from the center position C in the width direction of the belt layer 6, an effect of reducing road noise can be obtained. Rolling resistance deteriorates due to the increase in mass. 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 ridge 11 is located on the tread center side from the position P4 which 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.

The ridges 11 extend in the radial direction, and the extension direction is in the range of −30 ° to + 30 ° with respect to the radial direction. If the extending direction of the ridge 11 deviates from the above range, it is difficult to ensure the rigidity or effectiveness in suppressing the vibration. Further, the protrusion 11 may meander in a wavy manner in the above angle range.

  3 is an enlarged view of a main part of FIG. 1, and FIG. 4 is a cross-sectional view taken along the line AA of FIG. As shown in FIG. 3, the protruding amount of the protrusion 11 from the tire inner surface gradually increases from both ends in the longitudinal direction toward the center. Of course, the protrusion amount of the protrusion 11 may be uniform over the entire length. As shown in FIG. 4, the protrusion 11 has a cross-sectional shape in which the apex side is an arc shape. The cross-sectional shape of the ridge 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 inner surface of the tire where the protrusion 11 has the largest protrusion amount is preferably 2 mm or more. If the height h is less than 2 mm, the effect of reducing road noise is insufficient. On the other hand, if the height h exceeds 5 mm, the rolling resistance deteriorates due to an increase in mass. Therefore, the preferable range of the height h is 2 mm to 5 mm.

The width w of the portion in contact with the tire inner surface of the protrusion 11 shall be the 3 mm to 10 mm. If the width w is less than 3 mm, the effect of reducing road noise becomes insufficient. On the other hand, if the width w exceeds 10 mm, the rolling resistance deteriorates due to the increase in mass .

  The interval between the protrusions 11 in the tire circumferential direction is preferably 20 mm to 30 mm. If this distance is less than 20 mm, the rolling resistance deteriorates due to an increase in mass. Conversely, if it exceeds 30 mm, the effect of reducing road noise becomes insufficient. The intervals in the tire circumferential direction of the protrusions 11 may be uniform on the tire circumference or may be non-uniform.

Tire circumferential direction of the spacing of the ridges 11 is unevenly on tires laps in consideration of the variation in the groove area of the tread portion 1.

  FIG. 5 shows the relationship between the change in the groove area of the tread portion and the protrusions arranged in consideration of the change. In FIG. 5, the upper side of the alternate long and short dash line corresponds to a tread portion where the groove 12 is formed, and the lower side of the alternate long and short dash line corresponds to a buttress portion where the ridge 11 is formed. As shown in FIG. 5, when the number of the protrusions 11 is relatively increased in the portion where the groove area of the tread portion is relatively large, the mass imbalance caused by the change in the groove area is canceled, and the tire uniformity is reduced. Can be improved. Thus, the protrusion 11 can be used not only as a vibration suppressing means but also as a uniformity improving means.

  In a pneumatic tire having a tire size of 215 / 60R16 95H, tires of Conventional Examples 1-2, Examples 1-3, and Comparative Examples 1-5 having different tire inner surface shapes were produced.

  The tire of Conventional Example 1 has no protrusion on the tire inner surface of the buttress portion. The tire of Conventional Example 2 has a belt width 10 mm wider than that of Conventional Example 1 without providing protrusions on the tire inner surface of the buttress portion.

  In Examples 1 to 3 and Comparative Examples 1 to 5, 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. The position of the end of the ridge on the tread center side is indicated by the 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 of the ridge on the bead side indicates the tire cross-section height H. The distance from the tire maximum width position P2 is shown, and the extending direction of the ridge is shown by an angle with respect to the radial direction.

  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. The tires of Comparative Examples 1 to 3 and 5 were insufficient in reducing road noise. In the tire of Comparative Example 4, 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 the pneumatic tire of FIG. It is a principal part enlarged view of FIG. It is AA arrow sectional drawing of FIG. It is explanatory drawing which shows the relationship between the change of the groove area of a tread part, and the protrusion arranged considering the change.

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 Projection 12 Groove

Claims (3)

The region between the widthwise center position of the buried belt layer in the tread portion and the 2/3 position and the tire maximum width position of the belt half width, -30 ° ~ + 30 against the radial direction while protruding from the inner surface of the tire A plurality of ridges extending in the range of ° are formed at intervals in the tire circumferential direction, and one end of the ridge is located at 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 other 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 , The width of the portion of the ridge that is in contact with the inner surface of the tire is 3 mm to 10 mm, the intervals in the tire circumferential direction of the ridge are made uneven on the tire circumference, and the portion where the groove area of the tread portion is relatively large A pneumatic tire with a relatively large number of strips . The pneumatic tire according to claim 1, the height from the tire inner surface on the most protruding amount large portion of ridge was over 2 mm. The pneumatic tire according to claim 1 or 2 , wherein an interval between the protrusions in the tire circumferential direction is 20 mm to 30 mm.

Images