JP5207449B2 - Automotive tires - Google Patents

Description

  The present invention relates to an automobile tire in which air column resonance noise is reduced without deteriorating drainage performance.

  When the tire is grounded, a tubular space is formed by the main groove extending in the tire circumferential direction and the road surface. When the tire rotates, the compressed air is discharged to the tubular space, and as a result, air column resonance noise is generated. The air column resonance sound is annoying noise having a frequency of about 1 kHz, and it has been conventionally required to reduce the air column resonance sound. For example, in the pneumatic tire described in Patent Document 1, a large number of elongated holes extending in the main groove depth direction are provided on the side wall of the main groove. The long hole increases the frictional resistance against the air flow in the main groove, and as a result, the air column resonance noise is reduced.

Further, Patent Document 2 discloses a reinforced annular band disposed inside the tread portion in the radial direction without using air pressure, and a direction crossing the annular band from the reinforced annular band to the inside in the radial direction. extending, non-pneumatic tire which is supported by the structure having a plurality of web spokes are fixed to the wheel or hub is disclosed. Even in such a tire, it is desired to reduce air columnar resonance noise.

Japanese Patent Laid-Open No. 10-315711 Special Table 2005-500932 Publication

  However, the required performance for noise reduction of tires has become more severe in recent years, and further reduction of air column resonance noise is required. If the arrangement, width, and shape of the main groove are changed, the air columnar resonance noise can be greatly reduced. However, other tire performance such as drainage performance may be deteriorated.

  Therefore, an object of the present invention is to provide an automobile tire that can reduce air columnar resonance noise without deteriorating other tire performance by further improving the shape of the long hole (narrow groove).

The automobile tire of the present invention is an automobile tire in which a main groove extending in the tire circumferential direction is carved in a tread.
A first narrow groove extending in the groove depth direction is engraved on the side wall of the main groove, and a second narrow groove extending in the tire circumferential direction is engraved on the tread surface side of the side wall of the main groove ,
The second narrow groove is carved on the tread surface side from the boundary with a height of 30 to 60% of the depth D of the main groove from the groove bottom of the main groove .

  In the conventional technology, the narrow groove engraved on the side wall of the main groove and extending in the groove depth direction provides resistance to the air flow in the main groove, thereby reducing air column resonance noise. . The inventor paid attention to the phenomenon that when the tire is grounded, the side wall of the main groove is deformed so as to swell toward the side wall of the opposing main groove, and when the tire leaves the road surface, the side wall of the main groove returns to its original shape. . The inventor reduces the air column resonance noise more effectively by the deformation of the side wall and the air in the main groove is also discharged in the groove depth direction and resistance is given to the air flow in the groove depth direction. I found out that

  Therefore, in the automobile tire of the present invention, the second narrow groove gives resistance to the flow of the air in the main groove in the groove depth direction, and more effectively reduces the air column resonance noise.

  Hereinafter, embodiments of an automobile tire according to the present invention will be described with reference to the drawings. FIG. 1 is a view showing a side wall of a main groove of an automobile tire according to the present invention, and FIG. 2 is a view showing a part of a side wall 3 of the main groove 1. The main groove 1 extends in the tire circumferential direction R and forms a block 2 together with a lateral groove (not shown). A first narrow groove 11 and a second narrow groove 12 are carved on the side wall 3 and the opposite side wall (not shown) of the main groove 1.

  A first narrow groove 11 extending in the groove depth direction is carved on the side wall 3 of the main groove 1. Furthermore, a second narrow groove 12 extending in the tire circumferential direction is carved on the tread surface 5 side of the side wall 3. In addition, although the example of the tire in which the block was formed in the tread is shown, the same effect can be obtained by providing the narrow grooves 11 and 12 on the side walls on both sides of the main groove forming the rib.

  FIG. 3 shows a state of deformation of the main groove 1 when the tire contacts the road surface G. The side wall 3 of the main groove 1 is deformed so as to swell toward the opposite side wall. When the tire moves away from the road surface G, the side wall 3 of the main groove 1 returns to its original shape, but the deformation of the side wall 3 causes the air in the main groove 1 to be discharged also in the groove depth direction, increasing the air columnar resonance noise. Cause.

  Therefore, the first narrow groove 11 provides resistance to the air flowing in the groove direction in the main groove 1, and air column resonance noise can be reduced. Furthermore, since the second narrow groove 12 provides resistance to the air discharged from the main groove 1 in the groove depth direction, the air columnar resonance noise can be reduced more effectively.

  Although depending on the width W and depth D of the main groove 1, when the tire contacts the road surface G, the width is the largest at a position 30 to 60% of the depth D of the main groove 1 from the groove bottom 6. The main groove 1 is deformed so as to be narrow. Therefore, it is preferable that the second fine groove 12 is carved from the groove bottom 6 toward the tread surface 5 with the position B having a height D1 of 30 to 60% of the depth D of the main groove 1 as the boundary B.

As shown in FIG. 4, the first narrow groove 11 may be connected to the second narrow groove 12 located closest to the groove bottom 6. The first narrow groove 11, a plurality of second fine grooves 12, as shown in FIG. 5, all of the second narrow groove 12 as shown in FIG. 6, may be respectively linked manner. The second narrow groove 12 only needs to extend in the circumferential direction, and may be divided and extended in the circumferential direction as shown in FIG.

  The width w1 of the first narrow groove 11 is not less than 0.2 mm and not more than 0.2 times the depth D of the main groove 1, and the depth d1 is not less than 0.2 mm and the width W of the main groove 1 is 0. 5 times or less, the interval p1 is preferably 0.4 to 10.0 mm, and the length L1 is preferably 30 to 100% of the main groove depth D. The width w2 of the second narrow groove 12 is 0.2 mm or more and 0.1 times or less of the depth D of the main groove 1, and the depth d2 is 0.2 mm or more and is 0. 5 times or less, and the interval p2 is preferably 0.4 mm or more and 0.2 times or less of the depth D of the main groove 1. Out of these ranges, the widths w1 and w2 of the narrow grooves 11 and 12 become narrower, the depths d1 and d2 of the narrow grooves 11 and 12 become shallower, and the intervals p1 and p2 between the narrow grooves 11 and 12 become wider. In some cases, the air column resonance noise cannot be effectively reduced. Conversely, when the widths w1 and w2 of the narrow grooves 11 and 12 are widened, the depths d1 and d2 of the narrow grooves 11 and 12 are deepened, and the intervals p1 and p2 between the narrow grooves 11 and 12 are narrowed, The rigidity of the block 2 may become low, and other performances of the tire may deteriorate.

  The configuration of the main groove of the present invention can be applied to an automobile tire provided with a tread rubber that contacts the ground, and can be applied not only to a pneumatic tire but also to the above-described non-pneumatic tire.

  Example tires and comparative tires according to the present invention were manufactured and evaluated. The tread pattern is a pattern in which ribs 21 shown in FIG. 8 are formed, and the narrow grooves 11 and 12 are carved on both side walls 3 of all the main grooves 1. The tire size was 215 / 60R16, the rim size was 16 × 7-JJ, and the air pressure was 230 kPa.

  Examples 1 to 6 were tires provided with narrow grooves 11 and 12. The comparative example was a tire provided with only the second narrow groove 12 extending in the groove depth direction without including the first narrow groove 11 extending in the circumferential direction. The dimensions and form of each narrow groove were as shown in Table 1.

  The evaluation results are as shown in Table 1. The drainage performance is the speed at which hydroplaning begins to occur when the vehicle is mounted on a rear-wheel-drive sedan type passenger car with a displacement of 2500 cc and travels on a wet road with a water depth of 8 mm at an increased speed. It shows with the index which set the comparative example as 100, and shows that drainage performance is excellent, so that a number is large.

  The noise level is a bench test based on JASO-C606 (speed is 50 km / h), and the 1 kHz air column resonance sound level of 1/3 octave band is measured. It is represented by If the value is negative, the air column resonance sound level is reduced.

  According to Table 1, in the example tire, the air column resonance sound level was reduced without impairing the drainage performance.

It is a figure which shows the side wall of the main groove of the tire for motor vehicles which concerns on this invention. FIG. 3 is a view showing a part of the side wall 3 of the main groove 1. It is a figure which shows the deformation | transformation of a main groove. FIG. 3 is a view showing a part of the side wall 3 of the main groove 1. FIG. 3 is a view showing a part of the side wall 3 of the main groove 1. FIG. 3 is a view showing a part of the side wall 3 of the main groove 1. FIG. 3 is a view showing a part of the side wall 3 of the main groove 1. It is a figure which shows the tread pattern which concerns on an Example and a comparative example.

Explanation of symbols

1 Main Groove 2 Block 3 Main Groove Side Wall 11 First Fine Groove 12 Second Fine Groove

Claims (2)

In the automobile tire in which the main groove extending in the tire circumferential direction is carved in the tread,
A first narrow groove extending in the groove depth direction is engraved on the side wall of the main groove, and a second narrow groove extending in the tire circumferential direction is engraved on the tread surface side of the side wall of the main groove ,
An automobile tire characterized in that the second narrow groove is carved on the tread surface side from the boundary with a boundary of 30 to 60% of the depth D of the main groove from the groove bottom of the main groove. . The width w1 of the first narrow groove is not less than 0.2 mm and not more than 0.2 times the depth D of the main groove, and the depth d1 is not less than 0.2 mm and is equal to the width W of the main groove. 0.5 times or less, the interval p1 is 0.4 to 10.0 mm, the length L1 is 30 to 100% of the main groove depth D,
The width w2 of the second narrow groove is 0.2 mm or more and 0.1 times or less of the depth D of the main groove, and the depth d2 is 0.2 mm or more of the width W of the main groove. The automobile tire according to claim 1, wherein the tire is 0.5 times or less and the interval p <b> 2 is 0.4 mm or more and 0.2 times or less of the depth D of the main groove.

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