JP2011162162A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose a pneumatic tire with noise performance improved compared to conventional noise performance by improving a tread pattern. <P>SOLUTION: This pneumatic tire has a block row group 15 formed by mutually adjacently arranging two or more of block rows 13 of juxtaposing a plurality of blocks 12 partitioned by grooves 8 and 10 in the tire circumferential direction, in the tire width direction in a tread part 1, wherein in a block row group extending area being an area sandwiched by one side surface S1 and the other side surface S2 in the tire width direction of the block row group 15, assuming a maximum with of the blocks 12 as (a) and a maximum depth of the grooves 8 and 10 surrounding the blocks 12 as (b), [a/b] is 1 to 5, and the negative ratio which is the groove area ratio of the block row group extending area is 1.0% to 15.0%. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire having a plurality of blocks defined by grooves in a tread portion, and more particularly to a pneumatic tire that improves noise performance.

  In recent years, with the quietness of vehicles, the contribution of noise caused by tires to automobile noise has increased, and the reduction thereof has been demanded. The causes of noise directly radiated from the tire are mainly divided into pattern excitation sound, tire vibration sound, air column resonance sound, and tread slip sound. The pattern vibration sound is a sound that is radiated as a result of an impact input when the lateral groove constituting the tread pattern contacts the road surface, and the tire vibrates due to the impact input. The air column resonance sound is a sound generated by the resonance of the space formed by the grooves forming the tread pattern and the road surface, and the tread sliding sound is a sound generated by the slip of the rubber and the road surface. The sounds of interest in the present invention are pattern excitation sound and tire vibration sound.

  As a method for reducing the pattern excitation sound, a method of dispersing the frequency of the pattern excitation sound by adopting a pitch arrangement that changes individual pitch lengths in the block land portion row (for example, see Patent Document 1), There is known a technique for reducing the impact input by the lateral groove by reducing the ratio of the groove to the tread contact surface, that is, the negative rate. The reduction of the negative rate can be realized by making the block pattern a rib pattern or a pattern close to the rib pattern, and it is only necessary to use a tire that does not have a lateral groove in the extreme. The groove should be greatly reduced.

  On the other hand, as a technique for reducing tire vibration noise, a technique for reducing the compression rigidity of the tread is known. That is, either a material having a low elastic modulus is used as a tread rubber material, or a large number of transverse grooves are provided to increase the deformation in the transverse direction of the block and reduce the rigidity in the compression direction.

JP 2003-136914 A

  However, when trying to reduce the tire noise by designing the lateral groove of the tread pattern, the reduction of the pattern excitation sound and the tire vibration noise is contrary to each other, so that sufficient noise performance has not been obtained conventionally.

  Therefore, an object of the present invention is to propose a pneumatic tire having improved noise performance as compared with the conventional one by improving the tread pattern.

  The inventors have conducted extensive research on a tread pattern that can satisfy the above-mentioned purpose, and it is possible to optimize the negative rate and the size of each block in the tread pattern while suppressing tire vibration noise. The present inventors have found that it is advantageous for reducing the vibration noise and have completed the present invention. That is, the pneumatic tire according to the present invention includes at least two block rows in which a plurality of blocks partitioned by grooves are arranged in the tread portion in the tire circumferential direction and arranged adjacent to each other in the tire width direction. In the block row group extending region, which is a region sandwiched between one side surface and the other side surface in the tire width direction of each block row group, the block has a maximum width a, When the maximum depth of the enclosing groove is b, “a / b” is 1 or more and 5 or less, and the negative ratio which is the groove area ratio of the block row group extending region is 1.0% or more and 15.0%. It is characterized by the following. Here, the “maximum width” refers to the length of a line segment when the length of the line segment connecting two points on the peripheral edge of the block surface or the contour line takes a maximum value.

  According to the pneumatic tire adopting such a configuration, the negative rate and the size (maximum width) of each block are optimized in the block row group extending region in which two or more block rows are arranged adjacent to each other as a group. As a result, even if the negative rate is reduced, the maximum width of the block can be limited, and “a / b” is 1 to 5 and the negative rate is 1.0% to 15.0%, While ensuring the effect of reducing the pattern excitation sound due to the reduction in the groove area, the reaction force against the input to the tire due to road surface unevenness or the like decreases, and the tire vibration noise decreases. Moreover, since the noise performance is enhanced in the block row group extending region, a main groove or the like can be appropriately provided outside the region, so that it is easy to adjust the other performance in the pattern design. It becomes.

  In the pneumatic tire of the present invention, at least one block row group is provided in the tread portion, and extends in the tire circumferential direction between the block row groups and has a groove width larger than the groove. It is preferable to provide a circumferential main groove.

  In addition, in the pneumatic tire of the present invention, the tread portion has at least two circumferential main grooves on the outer side in the tire width direction from the tire equatorial plane, and the tire width direction outermost of the circumferential main grooves. It is preferable that both regions outside the circumferential main groove located on the outer side in the tire width direction are shoulder regions, and the block row group is arranged in at least one of the shoulder regions. Here, the “tread ground contact” is an industrial standard valid for the region where the tire is produced or used, for example, “Year Book” of The Tire and Rim Association Inc. in the United States, and The European Tire and Rim Technical Organization in Europe. “Standard Manual” of Japan, and in Japan, tires are assembled to standard rims at the applicable size of the standard described in the “JATMA Year Book” of the Japan Automobile Association, and the maximum load (maximum load capacity) and the maximum In the state where the air pressure corresponding to the load is applied, it is the outermost position in the tire width direction of the surface where the tire surface contacts the ground.

  According to the present invention, it is possible to propose a pneumatic tire with improved noise performance as compared to the conventional one by improving the tread pattern.

(A) is the partial expanded view which showed the tread pattern of the tire (tire of Example 1) of one Embodiment according to this invention, (b) followed the AA line in Fig.1 (a). It is sectional drawing. It is the figure which showed the relationship between the negative rate applied to this invention, the value of "a / b", and noise performance. (A)-(d) is the figure which showed the example of the other block shape applicable to this invention, respectively. 4 is a partial development view showing a tread pattern of a tire of Example 2. FIG. FIG. 4 is a partial development view showing a tread pattern of a tire of Example 3. 6 is a partial development view showing a tread pattern of a tire of Example 4. FIG. 4 is a partial development view showing a tread pattern of a tire of Comparative Example 1. FIG. 5 is a partial development view showing a tread pattern of a tire of Comparative Example 2. FIG. 6 is a partial development view showing a tread pattern of a tire of Comparative Example 3. FIG. It is the partial expanded view which showed the tread pattern of the pneumatic tire of the prior art (tire of the prior art example 1).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial development view showing a tread pattern of a pneumatic tire (hereinafter simply referred to as “tire”) according to an embodiment of the present invention.

  Although the tire of this embodiment is not shown in the figure, a pair of sidewall portions that are connected via a shoulder portion to the outer side in the width direction of the tread portion that forms the tread surface of the tire, and arranged radially inward of these sidewall portions. A tire structure according to a conventional example, comprising a pair of bead portions, a carcass extending in a toroidal shape between the pair of bead portions inside the tire, and a belt layer disposed radially outside the crown region of the carcass. Tire.

  As shown in FIG. 1, in the tire, a plurality of shoulder blocks 3 that extend over the tread portion 1 across the tread ground end TE and are partitioned by a bag groove-like lateral groove 2 are arranged side by side in the tire circumferential direction. A substantially rib-shaped shoulder block row 4 and a plurality of circumferential main grooves (in this case, one on each side of the tire equatorial plane E) arranged in the tire width direction inside the shoulder block row 4 and extending in the tire circumferential direction 5 is provided. Each of the circumferential main grooves 5 is preferably arranged in a region of 35% or less of the tread contact width TE in the tire width direction from the tire equatorial plane E. This is because the wear performance decreases when the block row width between the ground contact TE and the circumferential main groove is narrowed. The groove width of the circumferential main groove 5 is preferably 10 to 40% of the tread ground contact width TE in order to ensure sufficient drainage.

  In addition, the tire has a plurality of circumferences extending between the circumferential main grooves 5 and the shoulder block row 4 with a groove width smaller than the circumferential main grooves 5 and curved in an S shape in the tire circumferential direction. A plurality of rows of block rows 13 in which blocks 12 defined by the direction sub-grooves 8 and the plurality of lateral grooves 10 extending across the circumferential sub-grooves 8 are arranged in the tire circumferential direction are adjacent to each other in the tire width direction. A block row group 15 is provided. A similar block row group 15 is also provided between the circumferential main grooves 5. Therefore, when both regions outside the circumferential main groove 5 in the tire width direction are shoulder regions R1, R2, the block row group 15 is arranged in the left and right shoulder regions R1, R2. Three or more circumferential main grooves may be disposed, and in this case, both the outer regions in the tire width direction than the circumferential main grooves located on the outermost side in the tire width direction among the plurality of circumferential main grooves are respectively shouldered. A zone.

  In the present invention, for the sake of convenience, a region sandwiched between one side surface S1 and the other side surface S2 in the tire width direction of each block row group 15 (a region indicated by hatching in FIG. 1) is referred to as a block row group extending region. In each block row group extending region, “a / b” is 1 where the maximum width of the block 12 is a and the maximum depth of the grooves 8 and 10 surrounding the block 12 is b (see FIG. 1B). The negative ratio, which is the groove area ratio in each block row group extending region, is in the range of 1.0% to 15.0%. “A / b” is preferably 3. Here, “the groove surrounding the block” refers to the circumferential sub-groove 8 and the lateral groove 10, and “the maximum depth of the groove surrounding the block” refers to the depth of the circumferential sub-groove 8 or the lateral groove 10. It shall be the maximum depth of the larger of.

  The blocks 12 in each block row group extending region are arranged in a staggered manner. That is, the blocks 12 in the block row 13 adjacent in the tire width direction are arranged so that the phases are different from each other in the tire circumferential direction. Here, “the phase is different in the tire circumferential direction” means that, for example, in the example of FIG. 1, each block 12 is shifted by half a pitch in the tire circumferential direction between adjacent block rows 13 and 13. Say that. By adopting such a staggered arrangement, the grounding timing of the lateral grooves 10 can be shifted, which is advantageous for reducing pattern noise. Moreover, as shown in FIG. 1, pattern noise can be further reduced by shifting the position of the lateral groove 10 in the tire circumferential direction between all the block rows 13 and 13.

  According to the tire adopting such a configuration, in the block row group extending region in which two or more block rows 13 are arranged adjacent to each other, the negative rate and the size of each block 12 (“a / b”) Therefore, the maximum width a of the block 12 can be limited even if the negative rate is lowered, and “a / b” is 1 to 5 and the negative rate is 1.0% to 15.0. By setting the ratio to less than or equal to%, the reaction force against the input to the tire due to road surface unevenness or the like can be reduced and the tire vibration noise can be reduced while ensuring the effect of reducing the pattern excitation sound due to the reduction in the groove area. In addition, since the noise performance is enhanced in each block row group extending region, a main groove or the like can be appropriately provided outside the region, and adjustment with other performance can be achieved in pattern design. It becomes easy.

  Further, by setting “a / b” to 1 to 5 and the negative rate to 1.0% to 15.0%, the edge component by the block 12 is increased while ensuring the required block rigidity. Therefore, wet performance and further on-ice performance can be improved. Moreover, since the surface area of the block 12 is relatively small, the grounding property of each block 12 can be improved, and the distance from the central area to the peripheral edge on the surface of the block 12 can be reduced. The water film can be efficiently removed when the block 12 is grounded, which also contributes to the improvement of the wet performance.

  The reason why “a / b” is 1 or more and 5 or less and the negative rate is 1.0% or more and 15.0% or less in the block row group extending region is shown in FIG. This is because a good noise performance can be obtained as can be seen from the relationship between the negative rate and “a / b” and the noise performance, and furthermore, a balance with other performances can be secured, that is, “a / b”. Is less than 1, it is not preferable from the viewpoint of securing the steering stability and wear resistance, and if “a / b” exceeds 5, the compression rigidity of each block 12 becomes too large. This is not preferable because there is a possibility that the effect of reducing the vibration noise (effect of absorbing or attenuating vibration) due to the road surface unevenness targeted by the present invention may not be obtained. Further, when the negative rate is less than 1.0% in the block row group extending region, there is a possibility that the minimum wet performance that should be ensured in the block row group extending region may not be obtained. If it exceeds 15.0%, the effect of reducing the pattern excitation sound targeted by the present invention may not be sufficiently obtained, which is not preferable.

  Further, according to the tire of this embodiment, two or more block row groups 15 are provided in the tread portion 1, and the grooves 8 and 10 extend in the tire circumferential direction between the block row groups 15 and 15 and surround the block 12. Since the circumferential main groove 5 has a large groove width, the noise performance can be improved in the block row group extending region, while the drainage performance can be ensured in the other region. The negative effect on drainage due to the decrease in the negative rate can be eliminated.

  Furthermore, according to the tire of this embodiment, since the block row group 15 is arranged in the shoulder regions R1, R2, the rolling resistance can be advantageously reduced. This is because the region dominant to the rolling resistance is the region near the belt end of the tread portion 1, that is, the shoulder regions R1 and R2, and a plurality of relatively small blocks 12 are provided in the shoulder regions R1 and R2. This is because the tread portion 1 can be subdivided to make the vicinity of the belt end of the tread portion 1 flexible, and the energy loss of the tread portion 1 during tire load rolling can be significantly reduced.

  By the way, in the example mentioned above, although the surface outline shape of the block 12 was made into the octagon, it is not limited to this, As shown to Fig.3 (a)-(d), it is a square, a pentagon, and a hexagon. In such a case, the maximum width a of the block 12 is the maximum value of the length of the line segment connecting two points on the peripheral edge of the block 12 or on the contour line. It can be obtained as the length of that line segment.

  Next, tires of Examples 1 to 4 according to the present invention, tires of Conventional Example 1 according to the prior art, and tires of Comparative Examples 1 to 3 were respectively prototyped and subjected to various performance evaluations. These tires are all radial tires for passenger cars having a tire size of 195 / 65R15. Table 1 shows the specifications of each tire. In addition, in FIG. 10, the part painted in satin shows a groove | channel, and the part adjacent to the said groove | channel is a land part. In Table 1, “negative rate” refers to the negative rate of the block row group extending region, and “tread negative rate” refers to the negative rate of the entire tread including the circumferential main groove.

  About each said test tire, the following tests were done and performance was evaluated.

(1) Noise performance The noise performance was measured in accordance with the tire single-body noise measurement method in European vehicles described in ECER117. The internal pressure and load of the tire were determined according to the measurement method according to the vehicle used. The evaluation is “−3 dB” when the noise level is 2.5 dB to 3.4 dB lower, “−2 dB” when the noise level is 1.5 dB to 2.4 dB lower, and 0.5 dB to 1.4 dB lower than the conventional example 1. The case is assumed to be “−1 dB”. If it is less than ± 0.5 dB compared to Conventional Example 1, it is set to “0 dB”. Further, it is “+1 dB” when it is higher by 0.5 to 1.4 dB, “+2 dB” when it is higher by 1.5 dB to 2.4 dB, and “+3 dB” when it is higher by 2.5 dB to 3.4 dB. Since this test method is an evaluation based on the overall value of tire noise, it can be considered that the effect is sufficient even if the reduction is, for example, 0.5 dB. The evaluation results are shown in Table 2.

(2) Steering stability performance The circuit course in a dry state was subjected to sports driving in various driving modes and evaluated based on the feeling of a test driver. The evaluation results are shown in Table 2. The evaluation in Table 2 is the index of the tires of Examples 1 to 4 and the tires of Comparative Examples 1 to 3 with the result of Conventional Example 1 being 100. The larger the value, the better the steering stability. It shows that.

  From the results shown in Table 2, it can be seen that the application of the present invention improved the noise performance as compared with the prior art. Moreover, it turns out that required steering stability can be ensured by application of this invention.

  Thus, according to the present invention, it has become possible to propose a pneumatic tire having improved noise performance as compared with the prior art by improving the tread pattern.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Horizontal groove 3 Shoulder block 4 Shoulder block row | line | column 5 Circumferential direction main groove 8 Circumferential direction auxiliary groove 10 Horizontal groove 12 Block 13 Block row 15 Block row group

Claims (3)

The tread portion includes at least one block row group formed by arranging two or more block rows arranged in the tire circumferential direction adjacent to each other in the tire width direction.
In the block row group extending region, which is a region sandwiched between one side surface and the other side surface of each block row group in the tire width direction, the maximum width of the block is a, and the maximum depth of the groove surrounding the block is b As described above, “a / b” is 1 or more and 5 or less, and the negative ratio that is the groove area ratio of the block row group extending region is 1.0% or more and 15.0% or less. Pneumatic tire.   The tread portion includes two or more block row groups, and has at least one circumferential main groove extending in the tire circumferential direction between the block row groups and having a groove width larger than the groove. Pneumatic tires.   The tread portion has at least two circumferential main grooves on the outer side in the tire width direction from the tire equatorial plane, and the outer side in the tire width direction than the circumferential main groove located on the outermost side in the tire width direction among the circumferential main grooves. The pneumatic tire according to claim 1 or 2, wherein each of the regions is defined as a shoulder region, and the block row group is disposed in at least one of the shoulder regions.

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