JP2015066990A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of enhancing a grounding property while reducing tube resonance sound.SOLUTION: In a pneumatic tire provided, in a tread part 10, with a main groove 12 extending in a tire circumferential direction X, a lateral groove 14 extending in a direction intersecting the tire circumferential direction X, and a block 22 partitioned by the main groove 12 and the lateral groove 14, holes 28 are arranged at an interval in the tire circumferential direction X on a side wall 26 of a block 22 facing the main groove 12. The holes 28 arranged on a central part 30 side of the block 22 are closer to a ground contact surface 34 of the block 22 than the holes 28 arranged on end parts 32, 32 sides of the block 22.

Description

  The present invention relates to a pneumatic tire.

  Some pneumatic tires include a land portion on the surface of a tread portion that is divided by a main groove extending in the tire circumferential direction and a lateral groove intersecting the main groove. In a tire provided with such a groove in the tread portion, pattern noise is generated between the tire and the road surface during traveling, and in particular, air column resonance noise (about 800 Hz to 1250 Hz) caused by the main groove is a major cause. It has become.

  The generation principle of the air column resonance sound is as follows. That is, when the tire contacts the ground, the volume changes due to deformation of the main groove, and the air trapped in the main groove repeatedly compresses and expands, so that the pumping sound from the grounded main groove space, that is, Generates air columnar resonance. At that time, the air column resonance noise increases when the pumping pressure of the air in the main groove increases.

  In order to reduce such air columnar resonance noise, it is effective to reduce the flow velocity of the air passing through the space of the grounded main groove.

  Therefore, by providing a plurality of holes along the tire circumferential direction on the side wall of the land portion facing the main groove, and increasing the frictional resistance between the side wall of the land portion facing the main groove and the air, the inside of the main groove is It has been proposed to suppress air columnar resonance generated by reducing the flow velocity of the passing air (for example, see Patent Documents 1 and 2 below).

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

  In the land part divided by the main groove and the horizontal groove like a block, there is a difference in rigidity between the end part side and the center part side in the tire circumferential direction, and the ground pressure in the center part of the land part is higher than the end part. . As described above, since the contact pressure is not uniform, there is a problem that the contact property of the land portion is low. As described above, in order to reduce air columnar resonance noise, it has been known to provide a plurality of holes in the side wall of the land portion, but the grounding property of the land portion is improved by using the hole portion. It was not known to do.

  This invention is made | formed in view of the above point, and it aims at providing the pneumatic tire which can improve a ground contact property, reducing air column resonance noise.

  A pneumatic tire according to the present invention includes a main groove extending in a tire circumferential direction, a lateral groove extending in a direction intersecting the tire circumferential direction, and a land portion partitioned by the main groove and the lateral groove in an air tread. In the entering tire, a plurality of hole portions are provided at intervals in a tire circumferential direction on the side wall of the land portion facing the main groove, and the hole portion provided on the center side of the land portion is It is provided at a position closer to the ground contact surface of the land portion than the hole portion provided on the end portion side of the land portion.

  According to the present invention, on the central portion side of the land portion, the hole portion is provided at a position close to the ground contact surface, and the friction resistance between the side wall of the land portion and the air is increased while reducing the rigidity of the central portion of the land portion. On the end side of the land portion, a hole is provided at a position away from the ground contact surface of the land portion, while suppressing a decrease in rigidity on the end side of the land portion, The frictional resistance can be increased. For this reason, air columnar resonance can be suppressed, and variations in the ground contact pressure in the tire circumferential direction can be suppressed to improve the ground contact performance.

The expanded view of the tread pattern of the pneumatic tire which concerns on 1st Embodiment. The side view of the land part in 1st Embodiment. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. (A) is a top view of a hole part, (b) is the BB sectional drawing of FIG. The side view of the land part which concerns on the example of a change of 1st Embodiment. The expanded view of the tread pattern of the pneumatic tire which concerns on 2nd Embodiment. The side view of the land part in 2nd Embodiment. It is a side view of the land part of the pneumatic tire which concerns on a comparative example.

(First embodiment)
The pneumatic tire according to the embodiment is not illustrated, but the pair of left and right bead portions and sidewall portions and the radially outer ends of the left and right sidewall portions are connected to each other between the sidewall portions. And a tread portion 10 provided. A carcass extending between a pair of bead portions is embedded in the tire, and the carcass is composed of at least one carcass ply passing through the sidewall portion from the tread portion 10 and having both ends locked at the bead portions. A belt is provided on the outer periphery side of the carcass in the tread portion 10 and reinforces the tread portion 10 on the outer periphery of the carcass.

  As shown in FIG. 1, a plurality of main grooves 12 extending in the tire circumferential direction X and a plurality of lateral grooves 14 extending in a direction crossing the tire circumferential direction X are provided on the surface of the tread portion 10. In this example, two inner center main grooves 12A and 12A arranged on both sides of the tire equator C, and two shoulder mains arranged on the outer side in the tire width direction Y of the center main groove 12A, respectively. Four main grooves 12 with grooves 12B and 12B are provided. Accordingly, the tread portion 10 includes a center region 16 on the tire equator C, a pair of left and right mediate regions 18 adjacent to the outer side in the tire width direction Y, and a pair of left and right shoulder regions 20 adjacent to the outer side in the tire width direction Y. With.

  On the surface of the tread portion 10, a plurality of blocks 22 are provided as land portions partitioned by the main groove 12 and the lateral groove 14. In this example, the land portion is formed as a rib 24 continuous in the tire circumferential direction X in the center region 16, but in the mediate region 18 and the shoulder region 20, a block row in which a plurality of blocks 22 are arranged in parallel. Is formed.

  In the mediate region 18 and the shoulder region 20, the lateral grooves 14 are arranged side by side in the tire circumferential direction X at a predetermined interval. The lateral grooves 14 extend along a direction perpendicular to the tire circumferential direction X, that is, the tire width direction Y. Therefore, as shown in FIG. 1, the block 22 defined by the lateral grooves 14 has a rectangular shape in plan view, and each corner is formed at a right angle.

  As shown in FIG. 2, the side wall 26 of the block 22 facing the main grooves 12 </ b> A and 12 </ b> B has a long hole-shaped hole portion 28 that is longer in the depth direction Z of the main grooves 12 </ b> A and 12 </ b> B than the tire circumferential direction X. Is provided.

  A plurality of holes 28 are provided at intervals in the tire circumferential direction X in the side wall 26 of each block 22, that is, in the region R sandwiched between the lateral grooves 14 adjacent in the tire circumferential direction X. The holes 28 are provided side by side in the tire circumferential direction X. However, the positions in the depth direction Z are not constant in the region R, and the holes 28 having different positions in the depth direction are in the tire circumferential direction X. It is provided in one row. Specifically, in each block 22, the hole portion 28 provided on the central portion 30 side in the tire circumferential direction X of the block 22 is provided in the hole portion 28 provided on the end portion 32 side in the tire circumferential direction X of the block 22. Rather than the ground contact surface 34 of the block 22.

  In this example, when the side wall 26 of the block 22 is divided into three regions of the central portion 30 and both end portions 32 and 32 in the tire circumferential direction X, the regions 30, 32, and 32 are each in the depth direction Z. A plurality of hole portions 28 are arranged in parallel at the same position so as to be adjacent to each other in the tire circumferential direction X. The hole portion 28 of the central portion 30 is provided at a position close to the ground plane 34, and the hole portions 28 of both end portions 32, 32 are provided at positions away from the ground plane 34. Thus, the change in the position of the hole 28 in the depth direction Z is completed within one block 22.

  As an example of various dimensions of the hole 28, when the width W of the main grooves 12A and 12B is 10 mm and the depth D of the main grooves 12A and 12B is 10 mm, the height of the hole 28 (that is, the depth direction) The length along Z) h is 1.0 to 3.0 mm, the width of the hole 28 (that is, the length along the tire circumferential direction X) w is 0.6 to 3.0 mm, and the depth of the hole 28. The length d from the side wall 26 of the block 22 to the bottom of the hole 28 can be 0.3 to 2.0 mm (see FIGS. 3 and 4). When the height h of the hole 28 is too small, the width w of the hole 28 is too small, or the depth d of the hole 28 is too small, the frictional resistance against the air flowing through the main grooves 12A and 12B. It is difficult to reduce the air column resonance noise. Further, when the height h of the hole 28 is too large, the width w of the hole 28 is too large, or the depth d of the hole 28 is too large, the rigidity of the block 22 is greatly reduced.

  The ratio (T / S) of the opening area T obtained by summing the areas where the hole portions 28 open to the side walls 26 to the area S of the side walls 26 of the block 22 provided with the plurality of hole portions 28 is 0.03 to 0.2. It is preferable to be within the range. If the area ratio is too small, the effect of reducing the air columnar resonance noise is small. Conversely, if the area ratio is too large, the rigidity of the block 22 is greatly reduced.

  The formation range P of the hole portion 28 in the depth direction Z of the main grooves 12A and 12B is, for example, p1 at a depth position of 0.5 mm from the ground contact surface 34 of the block 22, and is linear in the cross-sectional shape of the side wall 26 of the block 22. It is preferable that the contact point between the portion and the arc portion on the bottom side is within a range sandwiched between p1 and p2 with p2.

  In the case of the pneumatic tire as described above, the hole portion 28 provided in the central portion 30 of the block 22 is closer to the ground contact surface 34 of the block 22 than the hole portions 28 provided in both end portions 32 and 32 of the block 22. Therefore, the friction resistance between the side wall 26 of the block 22 and the air can be increased while lowering the rigidity at the central portion 30, and the block can be suppressed while suppressing the decrease in rigidity at the both end portions 32 and 32. The frictional resistance between the side wall 26 of 22 and the air can be increased. Generally, the ground pressure distribution in the block is higher at the center than at both ends, but the rigidity at the center 30 can be reduced by the arrangement of the hole 28, so that the ground pressure at the center is effective. Can be reduced. As a result, the flow velocity of the air passing through the space of the main grooves 12A and 12B is reduced to suppress air columnar resonance noise, while suppressing the variation (dispersion) of the ground pressure of the block 22 in the tire circumferential direction X, thereby reducing the ground contact. Can be improved.

  In addition, although the hole part 28 which has such an effect may be provided in all the side walls 26 facing the main grooves 12A and 12B of the block 22, it is only in a part of the side walls 26 facing the main grooves 12A and 12B. It may be provided. Moreover, you may provide in the side wall which faces not only the main groove 12 but the horizontal groove 14. FIG. That is, when a hole is provided in the side wall facing the lateral groove 14, the hole in the central portion in the width direction of the block 22 is provided at a position closer to the grounding surface 34 of the block 22 than the holes in both ends in the width direction. Also, the ground pressure in the width direction of the block 22 can be equalized and the ground performance can be improved.

  The arrangement of the holes 28 is not limited to the mode shown in FIG. 2. For example, as shown in FIG. 5A, the side wall 26 of the block 22 is placed in the center portion 30 and both end portions 32 in the tire circumferential direction X. , 32 and intermediate portions 36, 36 therebetween, the hole portion 28 of the central portion 30 is provided at a position closest to the ground plane 34, and the hole portions 28 of both ends 32, 32 are separated from the ground plane 34. The holes 28 of the intermediate portions 36 and 36 may be provided at an intermediate position in the depth direction Z at the farthest position. As described above, the plurality of hole portions 28 may be arranged in a step shape such that the center portion 30 side is closer to the ground surface 34 than the end portion 32 side of the block 22.

  Moreover, as shown in FIG.5 (b), the hole 28 adjacent to the tire circumferential direction X may be arrange | positioned so that at least one part may overlap in the depth direction Z of main groove 12A, 12B. In the example of FIG. 5B, the plurality of hole portions 28 are all arranged in a step shape so as to be closer to the ground plane 34 toward the central portion 30 side than the end portion 32 side of the block 22. Is disposed so as to overlap at least a part of the hole 28 adjacent to the tire circumferential direction X in the depth direction Z of the main grooves 12A and 12B. Therefore, the rigidity can be gradually changed from the central portion 30 of the block 22 to both end portions 32 and 32, and the difference in rigidity in the block 22 can be easily adjusted uniformly.

  As shown in FIG. 5C, the plurality of hole portions 28 may be provided at positions that gradually approach the ground plane 34 as they go from both end portions 32, 32 of the block 22 to the central portion 30. Thereby, it is easy to adjust the rigidity difference in the block 22 more uniformly, and the grounding property can be further improved.

(Second Embodiment)
A second embodiment will be described based on FIGS. 6 and 7. As shown in FIG. 6, in the tread portion 10 </ b> A according to the second embodiment, the lateral groove 14 extends in a direction inclined with respect to the tire width direction Y. Therefore, the block 22A defined by the lateral groove 14 has a parallelogram shape in plan view having an obtuse angle portion 38 and an acute angle portion 40 as shown in FIG. The obtuse angle portion 38 and the acute angle portion 40 are corner portions of the block 22A facing the main grooves 12A and 12B intersecting the transverse groove 14, and the obtuse angle portion 38 is partitioned at an obtuse angle between the main grooves 12A and 12B and the transverse groove 14. In the corner portion, the acute angle portion 40 is a corner portion defined by the main grooves 12A and 12B and the lateral groove 14 at an acute angle.

  As shown in FIG. 7, a plurality of hole portions 28 are provided at intervals in the tire circumferential direction X in the side wall 26 of each block 22A, that is, in a region R sandwiched between the lateral grooves 14 adjacent to the tire circumferential direction X. Yes. In this example, the hole portion 28 provided in the end portion 32 on the obtuse angle portion 38 side of the block 22A is closer to the ground contact surface 34 of the block 22A than the hole portion 28 provided in the end portion 32 on the acute angle portion 40 side. Is provided. The hole portion 28 provided in the end portion 32 on the obtuse angle portion 38 side of the block 22A is also provided at a position farther from the ground plane 34 than the hole portion 28 provided in the central portion 30 of the block 22A. Accordingly, in the depth direction Z of the main grooves 12 </ b> A and 12 </ b> B, the main grooves 12 </ b> A and 12 </ b> B are provided at positions between the hole portion 28 at the end portion 32 on the acute angle portion 40 side and the hole portion 28 at the central portion 30.

  In the pneumatic tire according to the second embodiment, the hole portion 28 provided on the obtuse angle portion 38 side of the block 22A has a contact surface 34 of the block 22A than the hole portion 28 provided on the acute angle portion 40 side of the block 22. Therefore, the obtuse angle portion 38 side has a higher effect of reducing the rigidity than the acute angle portion 40 side. Therefore, the rigidity difference between the obtuse angle portion 38 side and the acute angle portion 40 of the block 22A can be reduced while suppressing the air column resonance noise, and the contact pressure in the tire circumferential direction X in the block 22A can be equalized. It is also advantageous for suppressing heel and toe wear.

  Also in the second embodiment, as in the first embodiment, each hole 28 is disposed so as to overlap at least a part of the hole 28 adjacent to the tire circumferential direction X in the depth direction Z of the main grooves 12A, 12B. May be. Alternatively, the block 22A may be provided at a position gradually approaching the ground contact surface 34 as it goes from both end portions 32, 32 to the central portion 30. Thereby, the rigidity can be gradually changed from the end portion 32 on the obtuse angle portion 38 side of the block 22A to the end portion 32 on the acute angle portion 40 side through the central portion 30, and the rigidity difference in the block 22A can be adjusted uniformly. Cheap.

  About 2nd Embodiment, the other structure and effect are the same as 1st Embodiment, and description is abbreviate | omitted.

(Other embodiments)
According to the above embodiment, since the hole 28 has a long hole shape in the depth direction Z of the main grooves 12A and 12B as compared with the tire circumferential direction X, the hole 28 adjacent to the tire circumferential direction X and It is easy to overlap the depth direction Z, and the adjustment amount (the amount of change in rigidity) when adjusting the rigidity in the blocks 22 and 22A is increased, and the difference in rigidity in the blocks 22 and 22A is adjusted uniformly. Cheap. However, the hole 28 may be provided in a long hole shape that is longer in the tire circumferential direction X than in the depth direction Z, and is provided in a square shape or a circular shape in which the depth direction Z and the tire circumferential direction X are equal. Also good.

  In the above embodiment, the case where the blocks 22, 22A divided by the lateral grooves 14 in the tire circumferential direction X are land portions has been described. However, in the present invention, the land portions partitioned by the main grooves and the lateral grooves are as described above. It is not limited to the blocks divided in the tire circumferential direction. For example, in the rib extending in the tire circumferential direction defined by the main groove, the lateral groove is provided so as to terminate in the middle without completely dividing the rib, whereby the tire circumferential direction on one end side in the tire width direction It may be a land portion that is continuous with the other end portion and is partitioned in the tire circumferential direction. Even in such a rib-shaped land portion, a plurality of hole portions 28 may be provided at intervals in the tire circumferential direction X in the region R sandwiched between the lateral grooves adjacent in the tire circumferential direction, as in the above embodiment. .

  Although some embodiments have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

  In order to specifically show the configuration and effects of the above embodiment, a radial tire for a passenger car (size: 195 / 60R15, rim: 6J) was prototyped and performance evaluation was performed. The evaluation method is as follows.

(1) Grounding property The ground pressure and the ground pressure dispersion were measured with the standard rim described in JATM YEAR BOOK and the maximum load capacity and the corresponding air pressure, and the reciprocal of the ground pressure dispersion is shown in Table 1. 2, the value of Comparative Example 4 was displayed as an index with each value being 100. The larger the value, the smaller the variation in ground pressure and the better the grounding performance.

(2) Noise performance (Air columnar resonance)
The air column resonance sound is measured by measuring the 1 kHz air column resonance sound level of 1/3 octave band in a bench test (speed: 80 km / h) of a new tire in accordance with JASO C606, and converting the sound pressure level to energy. The value was converted into a value, and the reciprocal number was expressed as an index with Table 1 representing the value of Comparative Example 1 and Table 2 representing the value of Comparative Example 4 as 100, respectively. The larger the value, the smaller the air column resonance sound and the better the noise performance.

  The structures of tires according to Examples 1 to 5 and Comparative Examples 1 to 4 are shown in Table 1 below. Examples 1-4 and Comparative Examples 1-3 are tires having the tread pattern shown in FIG. 1, and Examples 5 and Comparative Example 4 are tires having the tread pattern shown in FIG. In Example 1, the hole part 28 shown in FIG. 2 is formed in the side wall 26 of the block 22, and in Examples 2-4, the hole part 28 shown in FIGS. 5A to 5C is provided in the side wall 26 of the block 22. In Example 5, the hole portion 28 shown in FIG. 7 was formed in the side wall 26 of the block 22A. In Comparative Example 1, as shown in FIG. 8A, the hole portion 28 is provided in a row at the same position in the center in the depth direction Z on the side wall 26 of the block 22. In Comparative Example 2, as shown in FIG. 8 (b), holes 28 are provided in a row at the same position on the side wall 26 of the block 22 near the bottom in the depth direction Z. In Comparative Example 3, as shown in FIG. 8C, holes 28 are provided in a row at the same position on the ground surface side in the depth direction Z on the side wall 26 of the block 22. In Comparative Example 4, as shown in FIG. 8 (d), the hole portion 28 is located in the center in the depth direction Z on the side wall 26 of the block 22A so that the obtuse angle portion 38 and the acute angle portion 40 have the same height. In the same position. In addition, the hole 28 with respect to the area S of the hole 28 and the main grooves 12A and 12B provided in the pneumatic tires of Examples 1 to 5 and Comparative Examples 1 to 4 and the main grooves 12A and 12B and the side wall 26 of the blocks 22 and 22A is the side wall. Tables 1 and 2 show the ratio (T / S) of the opening area T, which is the total area of the openings 26.

  Each of the above performance evaluations was performed on the pneumatic tires of Examples 1 to 5 and Comparative Examples 1 to 4, and the results are shown in Tables 1 and 2.

  From the results of Tables 1 and 2, it can be seen that the pneumatic tires of Examples 1 to 5 are superior in noise performance and have improved grounding performance as compared with the pneumatic tires of Comparative Examples 1 to 4.

DESCRIPTION OF SYMBOLS 10 ... Tread part, 12A, 12B ... Main groove, 14 ... Transverse groove, 22, 22A ... Block 26 ... Side wall, 28 ... Hole part, 30 ... Center part, 32 ... End part, 34 ... Grounding surface 38 ... Obtuse angle part, 40 ... acute angle part, X ... tire circumferential direction, Y ... tire width direction, Z ... depth direction

Claims (4)

In a pneumatic tire including a main groove extending in a tire circumferential direction, a lateral groove extending in a direction intersecting the tire circumferential direction, and a land portion partitioned by the main groove and the lateral groove in a tread portion,
A plurality of hole portions are provided at intervals in the tire circumferential direction on the side wall of the land portion facing the main groove, and the hole portion provided on the center side of the land portion is an end of the land portion. The pneumatic tire is provided at a position closer to the ground contact surface of the land portion than the hole portion provided on the portion side. The pneumatic tire according to claim 1, wherein the hole portion has a long hole shape that is longer in a depth direction of the main groove than in a tire circumferential direction. The pneumatic tire according to claim 1, wherein the hole portion is disposed so as to overlap with at least a part of the hole portion adjacent in the tire circumferential direction and a depth direction of the main groove. The land portion includes an obtuse angle portion partitioned at an obtuse angle by the main groove and the lateral groove, and an acute angle portion partitioned at an acute angle by the main groove and the lateral groove,
The hole portion provided at the end portion on the obtuse angle portion side is closer to the grounding surface than the hole portion provided at the end portion on the acute angle portion side, and provided in the center portion of the land portion. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is provided at a position farther from the contact surface than the hole.

Images