JP6124667B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that can improve noise performance by reducing air column resonance noise.

  When the tire rotates in a grounded state, air columnar resonance may be generated from a tubular space formed by a main groove extending in the tire circumferential direction and a road surface. The air column resonance sound is a noise having a frequency of about 1 kHz, which causes discomfort to the driver and also causes a sound outside the vehicle. Therefore, a method capable of reducing the air column resonance sound has been conventionally demanded.

  In the pneumatic tire described in Patent Documents 1 to 3 by the present applicant, a large number of long holes are provided in the side wall of the main groove, and the long holes extend in the depth direction of the main groove and are spaced in the tire circumferential direction. Is provided. According to such a configuration, the frictional resistance of the air flowing in the main groove is increased, and the air column resonance noise can be reduced. The present inventor has found that the air column resonance sound can be reduced and the noise performance can be improved by further improving the method.

Japanese Patent Laid-Open No. 10-315711 JP 2009-126312 A JP 2009-227222 A

  This invention is made | formed in view of the said situation, The objective is to provide the pneumatic tire which can improve noise performance by reducing an air column resonance sound.

  The above object can be achieved by the present invention as described below. That is, the pneumatic tire according to the present invention is a pneumatic tire in which a main groove extending along a tire circumferential direction is provided on a tread surface, and a non-flat portion constituted by a hole or a protrusion is formed on a side wall of the main groove. A plurality of first components formed and extending in the depth direction of the main groove and spaced apart in the tire circumferential direction; and the depth of the main groove more than the first component. A plurality of second components that are short in the vertical direction, and the second component is longer in the tire circumferential direction than the first component, and is not in contact with the first component. And are arranged in the tire circumferential direction so as to be alternately arranged.

  In this tire, the non-flat portion constituted by the hole or the protrusion is formed on the side wall of the main groove, so that the frictional resistance of the air flowing in the main groove increases. In addition, since the first component and the second component longer in the tire circumferential direction are alternately arranged in the tire circumferential direction, the pitch of the non-flat portions in the tire circumferential direction becomes variable. Furthermore, since the second component, which is shorter in the depth direction of the main groove than the first component, is arranged in the tire circumferential direction, the height at which the second component is arranged and the height at which the second component is not arranged. The repeating pattern of the non-flat part is different. As a result, air turbulence is likely to occur, air column resonance noise is reduced, and the frequency is dispersed by changing the degree of the sound in the depth direction of the main groove, thereby improving noise performance. be able to.

  It is preferable that both the first component and the second component are constituted by holes. This facilitates air turbulence in the main groove and increases the degree thereof, which is convenient for reducing air column resonance noise.

  It is preferable that a plurality of the second components are arranged at intervals in the depth direction of the main groove. Thereby, the second component is arranged at a plurality of locations in the depth direction of the main groove, and a region where the second component is not arranged between them is set. As a result, the non-flat portions having different repetitive patterns are alternately arranged in the depth direction of the main groove, so that the frequency of the air column resonance sound is effectively dispersed and the noise performance can be improved satisfactorily.

  In order to effectively reduce air columnar resonance, it is preferable that the first component and the second component are arranged away from the upper edge of the side wall of the main groove toward the groove bottom. Further, when the first component is inclined with respect to the depth direction of the main groove, the phase of the non-flat portion repeating pattern changes in the depth direction of the main groove. Turbulence is more likely to occur, and the effect of reducing air columnar resonance can be improved.

The top view which shows an example of the tread surface with which a pneumatic tire is equipped Perspective view showing the side wall of the main groove Front view showing the side wall of the main groove Sectional drawing which shows A position (AA arrow view), B position (BB arrow view), and C position (CC arrow view) of FIG. The front view which shows the side wall of the main groove in the conventional form Sectional drawing which shows X position (XX arrow view), Y position (YY arrow view), Z position (ZZ arrow view) of FIG. The front view which shows the side wall of the main groove in the form which is not included in this invention The front view which shows the side wall of the main groove in another embodiment Sectional drawing which shows D position (DD arrow view), E position (EE arrow view), and F position (FF arrow view) of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, a plurality of (four in this embodiment) main grooves 3 extending along the tire circumferential direction CD are provided on the tread surface TS included in the pneumatic tire of the present embodiment. Further, in addition to the main groove 3, a lateral groove 4 extending in a direction intersecting with the main groove 3 is also provided, and these separate the land portions 5 such as ribs and blocks.

  As shown in FIGS. 2 and 3, a non-flat portion 10 made of a hole is formed on the side wall 3 a of the main groove 3. A similar non-flat portion is formed on a side wall (not shown) opposite to this. The non-flat portion 10 includes a plurality of elongated holes 11 (an example of a first component) that extend in the depth direction DD of the main groove 3 and are spaced apart in the tire circumferential direction CD, and the elongated holes 11. Also has a large number of short round holes 12 (an example of the second component) in the depth direction DD of the main groove 3. That is, the length L1 of the long hole 11 and the length L2 of the round hole 12 in the depth direction DD of the main groove 3 satisfy the relationship L1> L2.

  The round holes 12 are longer in the tire circumferential direction CD than the elongated holes 11 and are arranged in the tire circumferential direction CD so as to be alternately arranged with the elongated holes 11 without contacting the elongated holes 11. Therefore, the width W1 of the long hole 11 and the width W2 of the round hole 12 in the tire circumferential direction CD satisfy the relationship of W1 <W2. In the present embodiment, a large number of the long holes 11 have the same shape, and are arranged at equal intervals in the tire circumferential direction CD. The large number of round holes 12 have the same shape and are arranged at equal intervals in the tire circumferential direction CD.

  Since the unevenness based on such a non-flat portion 10 is provided on the side wall 3a, the frictional resistance of the air flowing in the main groove 3 is increased, which contributes to the reduction of air column resonance noise. Moreover, since the long holes 11 and the round holes 12 longer in the tire circumferential direction CD are alternately arranged in the tire circumferential direction CD, the pitch of the non-flat portions 10 in the tire circumferential direction CD becomes variable. That is, at the height (A position and C position) at which the round holes 12 are arranged, the pitch of the holes is not constant as shown in FIG. On the other hand, when the non-flat part 20 which consists only of the long hole 21 is provided in the side wall 3a like FIG. 5, the pitch of the non-flat part 20 becomes constant like FIG.

  Furthermore, in the present embodiment, the round holes 12 shorter in the depth direction DD of the main groove 3 than in the long holes 11 are arranged in the tire circumferential direction CD. Therefore, the height at which the round holes 12 are arranged (position A and position C) and the height at which the round holes 12 are not arranged (position B) are not formed by the long holes 11 and the round holes 12 as shown in FIG. The repeating pattern of the flat part 10 is different. In this embodiment, the area | region without the round hole 12 is provided over the tire perimeter. On the other hand, in FIG. 5, the repetitive pattern of the non-flat portion 20 is the same as in FIG. 6 at each of the X position, the Y position, and the Z position.

  Based on this configuration, in this pneumatic tire, air turbulence is likely to occur in the main groove 3, and the velocity of air particles flowing in the main groove 3 is non-uniform, thereby reducing air column resonance noise. can do. It is convenient to prevent the round hole 12 from contacting the elongated hole 11 in order to generate air turbulence. In addition, since the cross-sectional shape of the side wall 3a is changed in the depth direction DD of the main groove 3 and the degree of turbulence is easily changed in the depth direction DD, the frequency of the air column resonance sound is dispersed. Noise performance can be improved effectively.

  The length L1 of the long hole 11 in the depth direction DD of the main groove 3 is preferably 50% or more of the depth D3 of the main groove 3, and more preferably 60% or more. By making the length L1 50% or more of the depth D3, it is easy to ensure the effect of reducing the air columnar resonance noise. The length L1 is preferably 90% or less of the depth D3 of the main groove 3, and more preferably 80% or less. By setting the length L1 to 90% or less of the depth D3, the rigidity of the land portion 5 can be secured and deterioration of tire performance can be prevented. The depth D3 of the main groove 3 is, for example, 7.0 to 20.0 mm.

  The length L2 of the round hole 12 in the depth direction DD of the main groove 3 is preferably 10% or more of the depth D3 of the main groove 3. By making the length L2 10% or more of the depth D3, it is easy to ensure the effect of reducing the air columnar resonance noise. The length L2 is preferably 50% or less of the length L1 of the long hole 11, and more preferably 40% or less. By setting the length L2 to 50% or less of the length L1, it is convenient to vary the degree of turbulent flow in the depth direction DD.

  The width W1 of the long hole 11 in the tire circumferential direction CD is preferably 0.2 mm or more, and more preferably 0.5 mm or more. By reducing the width W1 to 0.2 mm or more, it is easy to ensure the effect of reducing the air column resonance noise. Further, the width W1 is preferably 5.0 mm or less, and more preferably 3.0 mm or less. By setting the width W1 to 5.0 mm or less, the frictional resistance of the air flowing in the main groove 3 can be appropriately increased. The width W1 is smaller than the length L1, and the elongated hole 11 is formed to be elongated.

  The interval S1 between the long holes 11 is preferably 1.0 mm or more, and more preferably 2.0 mm or more. By setting the interval S1 to 1.0 mm or more, it becomes easy to arrange the round holes 12 having an appropriate size. The interval S1 is set larger than the width W1. Further, the interval S1 is preferably 10.0 mm or less, and more preferably 8.0 mm or less. By setting the interval S1 to 10.0 mm or less, the arrangement density of the long holes 11 and the round holes 12 is increased, which is convenient for reducing the air column resonance noise.

  The width W2 of the round hole 12 in the tire circumferential direction CD is preferably 1.1 times or more, and more preferably 1.2 times or more the width W1 of the long hole 11. By making the width W2 1.1 times or more the width W1, it is convenient to make the pitch of the non-flat portions 10 appropriately variable. Further, the width W2 is preferably 0.9 times or less, more preferably 0.8 times or less of the interval S1 of the long holes 11. By making the width W2 0.9 times or less of the interval S1, the round holes 12 can be easily arranged so as not to contact the long holes 11.

  The depth D1 of the long hole 11 and the depth D2 of the round hole 12 are set to 0.2 to 3.0 mm, for example. In the present embodiment, the depth D1 and the depth D2 are the same size, but they may be different. When making them different, it is preferable to make the depth D2 larger than the depth D1 from the viewpoint of suppressing deterioration of the rigidity of the land portion 5 and preventing deterioration of tire performance.

  The long hole 11 is disposed away from the upper edge 3b of the side wall 3a of the main groove 3 toward the groove bottom 3c, and terminates at the closed end 11a without reaching the upper edge 3b. Similarly, the round hole 12 is also arranged away from the upper edge 3b of the side wall 3a toward the groove bottom 3c. In this way, air columnar resonance noise can be effectively reduced because the long hole 11 and the round hole 12 do not open to the top surface of the land portion 5. The long hole 11 is arranged away from the groove bottom 3c of the main groove 3 toward the upper edge 3b, and terminates at the closed end 11b without reaching the groove bottom 3c. This is convenient for preventing cracks. Similarly, the round hole 12 is also arranged away from the groove bottom 3c toward the upper edge 3b.

  In the non-flat portion 10, a plurality of (two in the present embodiment) round holes 12 are arranged with an interval S <b> 2 in the depth direction DD of the main groove 3. Therefore, the round holes 12 are arranged at a plurality of locations (A position and C position) in the depth direction DD, and an area where the round holes 12 are not arranged is set between them (B position). In the A position and the C position, the pitch of the non-flat portion 10 is variable, so that air turbulence is likely to occur. However, between the A position and the C position, a region having a different repeated pattern is interposed. By doing so, the frequency of the air column resonance sound is effectively dispersed, and the noise performance can be improved satisfactorily.

  It is preferable that the round holes 12 are arranged at two or three places in the depth direction DD of the main groove 3, thereby easily forming the round holes 12 with an appropriate size. In order to secure the effect of dispersing the frequency of the air column resonance sound, the interval S2 between the round holes 12 in the depth direction DD of the main groove 3 is preferably 5 to 20% of the depth D3 of the main groove 3. The round hole 12 of the present embodiment is disposed closer to the groove bottom 3 c than the closed end 11 a of the elongated hole 11, and is disposed closer to the upper edge 3 b than the closed end 11 b of the elongated hole 11.

In the present embodiment, the round holes 12 aligned in the depth direction DD of the main groove 3 have the same shape, but these shapes and sizes may be different. In addition, the structure where the round hole 12 is arranged in the tire circumferential direction CD at one place in the depth direction DD of the main groove 3 as in the non-flat portion 30 shown in FIG. 7 is not included in the present invention.

  In the case where the non-flat portions 10 are formed on the side walls 3a on both sides of the main groove 3, the phase of the non-flat portion 10 on the one side wall 3a is repeated, and the non-flat portions 10 on the other side wall 3a are repeated. It is preferable to shift in the tire circumferential direction CD with respect to the pattern phase. This enhances the effect of dispersing the frequency of the air column resonance sound, which is convenient for improving noise performance.

  In the non-flat portion 40 shown in FIG. 8, the elongated holes 11 are inclined with respect to the depth direction DD of the main groove 3, and therefore the phase of the repetitive pattern of the non-flat portion 40 changes in the depth direction DD. To do. That is, the phase of the repetitive pattern of the non-flat portion 40 is different from each other at the D position, the E position, and the F position as shown in FIG. For this reason, the turbulent flow of the air flowing in the main groove 3 is more likely to occur, and the effect of reducing the air column resonance noise can be improved. The inclination angle θ of the elongated hole 11 with respect to the depth direction DD is preferably within 45 degrees in order to reduce air columnar resonance noise.

  In the above-described embodiment, the example in which the non-flat portion is configured by the hole has been described. However, in the present invention, the non-flat portion may be configured by the protrusion. That is, both or one of the first component and the second component may be a protrusion protruding from the side wall 3a of the main groove 3, and preferred dimensions and intervals thereof are the same as in the case of the hole. However, in consideration of the degree of generating turbulent flow in the air in the main groove and the drainage property in the main groove, it is preferable to form the non-flat portion with a hole as in the above-described embodiment.

  In the above-described embodiment, an example in which the second component has a round shape has been described. However, the present invention is not limited to this, and the second component may have other shapes such as a square shape, a triangular shape, a trapezoidal shape, and a parallelogram shape. It doesn't matter. However, in order to prevent cracks on the side walls of the main groove, the second component is preferably a round hole or a round protrusion as described above.

  In the present invention, the non-flat portion as described above can be formed on the side walls of all the main grooves in the tread surface, but only on the side walls of some main grooves in the tread surface. It doesn't matter. In addition, if the non-flat portion is formed on the side wall of the main groove in the tread surface that is continuously opened in the tire circumferential direction without opening the lateral groove, the effect of improving the noise performance is increased.

  The pneumatic tire of the present invention is a modification to the extent that the irregularities for forming the non-flat portion as described above are formed in the bone portion for forming the main groove provided in the tire mold, and the rest is a conventional tire manufacturing process. Manufacture can be performed in the same manner.

  The pneumatic tire of the present invention is the same as an ordinary pneumatic tire except that the non-flat portion as described above is formed on the side wall of the main groove, and any conventionally known material, shape, structure, etc. Can be adopted.

  The present invention is not limited to the embodiment described above, and various improvements and modifications can be made without departing from the spirit of the present invention.

  In order to show concretely the configuration and effect of the present invention, the noise performance was evaluated and will be described. The noise performance was evaluated by performing a bench test using a single tire in accordance with JASO-C606 and measuring the 1 kHz air column resonance sound level of 1/3 octave band at 80 km / h. The tire noise difference is evaluated based on the result of Comparative Example 1, and the larger the negative value, the better the noise performance.

  The size of the tire used for the evaluation was 225 / 45R17, and the non-flat portions of FIGS. 5 and 6 were formed as the non-flat portions of FIGS. What was formed was Example 1, and what was formed with the non-flat portion of FIGS. Except for the configuration related to the side wall of the main groove, the tire structure and the rubber composition in each example are common, the depth of the main groove is 8 mm, and the depth of the hole is 0.3 mm. The evaluation results are shown in Table 1. The interval S1 of Comparative Example 1 is a value measured every other interval as shown in FIG.

  As shown in Table 1, the air columnar resonance noise can be reduced in Examples 1 and 2 compared to Comparative Example 1, and the improvement effect of Example 2 is particularly great.

3 main groove 3a side wall 3b upper edge 3c groove bottom 10 non-flat part 11 long hole (example of first component)
12 round holes (example of second component)

Claims (4)

In the pneumatic tire in which the main groove extending along the tire circumferential direction is provided on the tread surface,
A non-flat portion constituted by a hole or a protrusion is formed on the side wall of the main groove,
The non-flat portion extends in the depth direction of the main groove and is arranged at intervals in the tire circumferential direction, and the depth direction of the main groove is greater than the first component. A number of short second components,
Said second component, together with a long in the tire circumferential direction than the first component, it has been arranged on the first component and the tire circumferential direction and alternately arranged without contact with the first component The pneumatic tire is characterized in that a plurality of the second components are arranged at intervals in the depth direction of the main groove .   The pneumatic tire according to claim 1, wherein both the first component and the second component are configured by holes. The pneumatic tire according to claim 1 or 2 , wherein the first component and the second component are disposed away from the upper edge of the side wall of the main groove toward the groove bottom side. The pneumatic tire according to claim 1, wherein the first component is inclined with respect to a depth direction of the main groove.