JP2012188048A - Tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire that increases drainage performance and reduces noise at a high level.SOLUTION: A plurality of first circumferential auxiliary grooves 31a, 31b, 31c, 31d, 31e, 31f which extend in the tire circumferential direction TC are formed in the first shoulder land portion 25 of the pneumatic tire 1. A plurality of second circumferential auxiliary grooves 32a, 32b, 32c, 32d which extend in the tire circumferential direction TC are formed in the second shoulder portion 27 thereof. The number of the first circumferential auxiliary grooves 31 is larger than that of the second circumferential auxiliary grooves 32.

Description

  The present invention relates to a tire in which a plurality of circumferential grooves extending in the tire circumferential direction are formed on the surface of a tread.

  Conventionally, in addition to a circumferential groove extending along the tire circumferential direction, a lug groove extending in a direction intersecting the tire circumferential direction is formed in the tire. By forming the lug groove, water between the road surface and the tire contact surface is pushed out toward the outside in the tread width direction. Thereby, drainage property is improved and the braking performance of the tire on a wet road surface can be ensured (refer to patent documents 1).

JP 2010-23549 A (5th page, FIG. 1 etc.)

  However, as described in Patent Document 1, the lug groove extending in the tread width direction contributes to drainage, while the edge of the block formed by the lug groove hits the road surface as the tire rolls. It can also be a cause of generation of noise (pattern pitch noise).

  In recent years, with the improvement of vehicle engine performance and the appearance of electric vehicles, noise caused by vehicles tends to be reduced. For this reason, the further improvement is calculated | required with respect to the noise resulting from a tire.

  Accordingly, an object of the present invention is to provide a tire that can achieve both high drainage and noise reduction at a high level.

  In order to solve the above-described problems, the present invention has the following features. A plurality of circumferential main grooves (circumferential main grooves 11, 13, 15) extending along the tire circumferential direction (tire circumferential direction TC) on the tread (tread 10) that contacts the road surface, and the plurality of circumferential main grooves And a pair of central land portions (first central land portion 21 and second central land portion 23) formed via the tire equator line (tire equator line CL), and the pair of land portions. A tire (a pneumatic tire 1) having a pair of shoulder land portions (first shoulder land portion 25, second shoulder land portion 27) formed on the outer side in the tread width direction, wherein the pair of central land portions are A first central land portion located on one side in the tread width direction from the tire equator line, and a second central land portion located on the other side in the tread width direction from the tire equator line, A pair of shoulder land parts are tires A first shoulder land portion formed on the shoulder portion on one side in the tread width direction from the road line; a second shoulder land portion formed on the shoulder portion on the other side in the tread width direction from the tire equator line; A plurality of first lug grooves (first lug grooves 41, 42) extending in the tread width direction and aligned along the tire circumferential direction are formed in the first central land portion, 2 A plurality of second lug grooves (second lug grooves 43, 44) extending in the tread width direction and arranged along the tire circumferential direction are formed in the central land portion, and the depth of the first lug groove (D1) is deeper than the depth (D2) of the second lug groove, and the first shoulder land portion includes a plurality of first circumferential subgrooves (first circumferential subgrooves) extending along the tire circumferential direction. 31a, 31b, 31c, 31d, 31e, 31f) are formed, and the second A plurality of second circumferential sub-grooves (second circumferential sub-grooves 32a, 32b, 32c, 32d) extending along the tire circumferential direction are formed in the rudder land portion, and the first circumferential sub-groove and the first circumferential groove are formed. The width in the tread width direction of the two circumferential subgrooves is narrower than the width in the tread width direction of the circumferential main groove, and the number of the first circumferential subgrooves is larger than the number of the second circumferential subgrooves. The main point is that there are many.

  In the above-described feature of the present invention, at least three circumferential main grooves may be formed in the tread.

  In the above-described feature of the present invention, at least one of the plurality of first circumferential sub-grooves is formed outside a grounding end portion on the outer side in the tread width direction in a state where the tire is grounded on the road surface. In addition, at least one of the plurality of second circumferential sub-grooves may be formed on the outer side of the grounding end portion on the outer side in the tread width direction in a state where the tire is grounded.

  In the above-described feature of the present invention, the groove width in the direction orthogonal to the extending direction of the first lug groove and the groove width in the direction orthogonal to the extending direction of the second lug groove may be 1 mm to 2 mm. .

  In the above-described feature of the present invention, the depth of the first circumferential sub-groove is 0.35 to 0.6 of the depth of the circumferential main groove, and the depth of the second circumferential sub-groove is The depth of the circumferential main groove may be 0.20 to 0.60.

  In the above-described feature of the present invention, the inner second circumferential sub-groove located on the innermost side in the tread width direction among the plurality of second circumferential sub-grooves and the second adjacent to the inner second circumferential sub-groove. The space | interval with the circumferential direction subgroove may be formed so that it may become wider than the space | interval of other 2nd circumferential direction subgrooves.

  In the above-described feature of the present invention, a narrow groove having a narrower width in the tread width direction than the circumferential main groove is formed in the center of the first central land portion or the second central land portion in the tread width direction. May be.

  According to the present invention, it is possible to provide a tire capable of achieving both high drainage performance and noise reduction at a high level.

FIG. 1 is a development view of a tread of a pneumatic tire according to an embodiment of the present invention. 2 is a cross-sectional view taken along line AA shown in FIG. FIG. 3 is a sectional view of the pneumatic tire according to the embodiment of the present invention in the tread width direction and the tire radial direction. FIG. 4 is a diagram illustrating a sample used for comparative evaluation.

  An embodiment of a tire according to the present invention will be described with reference to the drawings. Specifically, (1) tire tread configuration, (2) circumferential sub-groove configuration, (3) action and effect, (4) comparative evaluation, and (5) other embodiments will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(1) Configuration of Tire Tread FIG. 1 is a development view of a tread that constitutes a pneumatic tire 1 according to an embodiment of the present invention. 2 is a cross-sectional view taken along line AA shown in FIG. The pneumatic tire 1 has a tread 10 that comes in contact with the road surface. The tread 10 is formed with a plurality of circumferential main grooves extending along the tire circumferential direction TC and a plurality of land portions extending in the tire circumferential direction TC.

  In the embodiment, the pneumatic tire 1 is formed with three circumferential main grooves 11, 13, 15 extending along the tire circumferential direction TC. Further, the pneumatic tire 1 is partitioned by the circumferential main grooves 11, 13, and 15, so that a pair of central land portions formed via the tire equator line CL and a tread than the pair of central land portions. A pair of shoulder land portions formed on the outer side in the width direction are formed.

  In the embodiment, the pneumatic tire 1 is formed with a first central land portion 21 partitioned by the circumferential main groove 11 and the circumferential main groove 13. The pneumatic tire 1 is formed with a second central land portion 23 partitioned by the circumferential main groove 11 and the circumferential main groove 14.

  In the pneumatic tire 1, a first shoulder land portion 25 formed on the outer side in the tread width direction from the circumferential main groove 13 and a second shoulder formed on the outer side in the tread width direction from the circumferential main groove 15. A land portion 27 is formed.

  The first central land portion 21 is formed with a plurality of first lug grooves 41 and 42 that extend in the tread width direction TW and are aligned along the tire circumferential direction TC. The second central land portion 23 is formed with a plurality of second lug grooves 43 and 44 extending in the tread width direction TW and aligned along the tire circumferential direction TC. In the embodiment, the depth D1 of the first lug grooves 41 and 42 is deeper than the depth D2 of the second lug grooves 43 and 44 (see FIG. 2).

  The groove width Wm1 in the direction orthogonal to the extending direction of the first lug grooves 41 and 42 and the groove width Wm2 in the direction orthogonal to the extending direction of the second lug grooves 43 and 44 are 1 mm to 2 mm.

  In addition, narrow grooves 51 and 52 that are narrower in the tread width direction than the circumferential main grooves 11, 13, and 15 are formed in the center portions in the tread width direction of the first central land portion 21 and the second central land portion 23. Has been.

  A plurality of first circumferential sub-grooves 31a, 31b, 31c, 31d, 31e, and 31f extending along the tire circumferential direction TC are formed in the first shoulder land portion 25. The second shoulder land portion 27 is formed with a plurality of second circumferential sub-grooves 32a, 32b, 32c, and 32d extending along the tire circumferential direction TC.

(2) Configuration of circumferential sub-groove FIG. 3 is a cross-sectional view of the pneumatic tire 1 according to the embodiment of the present invention in the tread width direction and the tire radial direction. The width in the tread width direction of the first circumferential sub-grooves 31a, 31b, 31c, 31d, 31e, and 31f is narrower than the width of the circumferential main grooves 11, 13, and 15. The width in the tread width direction of the second circumferential sub-grooves 32a, 32b, 32c, and 32d is narrower than the width of the circumferential main grooves 11, 13, and 15. The first circumferential sub-grooves 31a, 31b, 31c, 31d, 31e, 31f may be formed to have the same width as the second circumferential sub-grooves 32a, 32b, 32c, 32d. In the embodiment, the number of first circumferential sub-grooves 31 is greater than the number of second circumferential sub-grooves 32.

  FIG. 3 shows ground contact end lines L1 and L2 corresponding to the outer ends in the tread width direction of the ground shape when the pneumatic tire 1 is grounded on the road surface. In the embodiment, the first circumferential sub-groove 31f is formed on the outer side in the tread width direction than the ground end line L1. The second circumferential sub-groove 32d is formed on the outer side in the tread width direction than the ground end line L2.

  In the embodiment, the depth D4 of the first circumferential sub-grooves 31a, 31b, 31c, 31d, 31e, and 31f is 0.35 to 0.6, which is the depth D3 of the circumferential main grooves 11, 13, and 15. (That is, D4 / D3 = 0.35-0.60), the depth D5 of the second circumferential sub-grooves 32a, 32b, 32c, 32d is 0. 0 of the depth D3 of the circumferential main grooves 11, 13, 15. 20 to 0.60 (that is, D5 / D3 = 0.20 to 0.60).

  Further, among the plurality of second circumferential sub-grooves 32a, 32b, 32c, 32d, a second circumferential sub-groove 31a (which constitutes an inner second circumferential sub-groove) located on the innermost side in the tread width direction; The interval Wa between the second circumferential sub-groove 31b adjacent to the second circumferential sub-groove 31a is between the other second circumferential sub-grooves (the second circumferential sub-groove 32b and the second circumferential sub-groove 32c). It is wider than the interval Wc.

(3) Action / Effect The first shoulder land portion 25 of the pneumatic tire 1 according to the embodiment includes a plurality of first circumferential sub-grooves 31a, 31b, 31c, 31d, 31e extending along the tire circumferential direction TC. 31f is formed. The second shoulder land portion 27 is formed with a plurality of second circumferential sub-grooves 32a, 32b, 32c, and 32d extending along the tire circumferential direction TC.

  In the pneumatic tire 1, the first shoulder land portion 25 and the second shoulder land portion 27 are so-called plain ribs that are not formed with lug grooves along the tread width direction. The occurrence of noise (pattern pitch noise) due to this can be suppressed.

  Moreover, in the pneumatic tire 1, instead of forming lug grooves in the first shoulder land portion 25 and the second shoulder land portion 27, the first circumferential sub-grooves 31a, 31b, 31c, 31d, 31e, 31f, second Circumferential sub-grooves 32a, 32b, 32c, and 32d are formed. Thereby, in the tread width direction outer side, the effect which drains the water between a road surface and a tire ground-contact surface from the rotation direction front side of a tire to the back side can be heightened.

  In the pneumatic tire 1, the first central land portion 21 is formed with a plurality of first lug grooves 41 and 42 extending in the tread width direction and aligned along the tire circumferential direction. The portion 23 is formed with a plurality of second lug grooves 43 and 44 extending in the tread width direction and arranged in the tire circumferential direction. Thereby, in the pneumatic tire 1, the water between the road surface and the ground contact surface of the tire is drained to the nearest circumferential main grooves 11, 13, 15 in the first central land portion 21 and the second central land portion 23. easy.

  Therefore, the pneumatic tire 1 can suppress the occurrence of pattern pitch noise while ensuring the braking performance of the tire on a wet road surface.

  In the pneumatic tire 1 according to the embodiment, the number of the first circumferential sub-grooves 31 is larger than the number of the second circumferential sub-grooves 32. Therefore, when the pneumatic tire 1 is mounted on the vehicle, the first central land portion 21 and the first shoulder land portion 25 are located on the vehicle inner side, and the second central land portion 23 and the second shoulder land portion 27 are on the vehicle outer side. When mounted so as to be positioned, the number of grooves on the inner side of the vehicle is large, so that the braking performance of the tire when traveling straight on a wet road surface can be ensured. Further, since the number of grooves on the vehicle outer side is small during cornering, the pattern rigidity on the outer side in the tread width direction where the contact pressure is increased can be ensured. As a result, DRY performance can be ensured.

  The pneumatic tire 1 can suppress the occurrence of pattern pitch noise without impairing the braking performance of the tire on a wet road surface and the steering stability during cornering.

  In the pneumatic tire 1, at least one of the first circumferential sub-grooves (in the embodiment, the first circumferential sub-groove 31 f) is on the outer side in the tread width direction when the pneumatic tire 1 is in contact with the road surface. It is formed outside the ground end line L1 defined at the ground end. Further, at least one of the second circumferential sub-grooves (in the embodiment, the second circumferential sub-groove 32d is formed outside the ground end line L2. Accordingly, the first shoulder land portion 25 is formed. The effect which excludes the water which contacts the side surface of the 2nd shoulder land part 27 to the tread width direction outer side is heightened.

  In the pneumatic tire 1, the groove width Wm1 of the first lug grooves 41 and 42 and the groove width Wm2 of the second lug grooves 43 and 44 are 1 mm to 2 mm. When the groove widths Wm1 and Wm2 are 1 mm or less, the effect of draining water between the road surface and the ground contact surface is insufficient, and when the groove width is 2 mm or more, uneven wear such as heel and toe wear easily occurs. Since the pattern rigidity is insufficient, the steering stability may be lowered.

  During cornering, the ground contact area of the pneumatic tire 1 is larger toward the vehicle outer side and smaller toward the vehicle inner side. That is, the ground contact shape changes to a fan shape or a trapezoidal shape. On the other hand, in the pneumatic tire 1, the depth D1 of the first lug grooves 41, 42 is formed deeper than the depth D2 of the second lug grooves 43, 44, and the first circumferential sub-grooves 31a, The depth D4 of 31b, 31c, 31d, 31e, 31f is 0.35 to 0.6 of the depth D3 of the circumferential main groove, and the depth of the second circumferential subgrooves 32a, 32b, 32c, 32d. D5 is 0.20 to 0.60 of the depth D3 of the circumferential main groove.

  That is, the drainage capacity of the first circumferential sub-grooves 31a, 31b, 31c, 31d, 31e, 31f is greater than the drainage capacity of the second circumferential sub-grooves 32a, 32b, 32c, 32d.

  Therefore, when the pneumatic tire 1 is mounted on the vehicle, the first central land portion 21 and the first shoulder land portion 25 are located on the vehicle inner side, and the second central land portion 23 and the second shoulder land portion 27 are on the vehicle outer side. When mounted so as to be positioned, the drainage capacity on the vehicle inner side is increased, so that the braking performance of the tire when traveling straight on the wet road surface can be ensured in the vehicle inner part. Further, at the time of cornering, the pattern rigidity on the outer side in the tread width direction where the contact pressure is increased can be ensured on the outer side of the vehicle. As a result, DRY performance can be ensured.

  In the pneumatic tire 1, the interval between the second circumferential sub-groove 32 a located on the innermost side in the tread width direction and the second circumferential sub-groove 32 b adjacent to the second circumferential sub-groove 32 a is different from each other. It is wider than the interval between the second circumferential sub-grooves (32b to 32d).

  In this manner, by increasing the distance between the second circumferential sub-groove 32a and the second circumferential sub-groove 32b, it is possible to ensure a ground contact area during cornering and improve braking performance.

  In the pneumatic tire 1, a narrow groove 51, which is narrower in the tread width direction than the circumferential main grooves 11, 13, 15 in the center of the first central land portion 21 or the second central land portion 23 in the tread width direction. 52 is formed.

  By the narrow grooves 51 and 52, the first central land portion 21 and the second central land portion 23 are easily deformed at the time of ground contact, and the shear stress accumulated in the first central land portion 21 and the second central land portion 23 at the time of ground contact. Can be released. For this reason, uneven wear such as heel and toe wear in which the edge portions of the first lug grooves 41 and 42 and the second lug grooves 43 and 44 wear preferentially can be prevented.

(4) Comparative Evaluation Next, in order to further clarify the effects of the present invention, comparative evaluation performed using pneumatic tires according to the following examples will be described. Specifically, (4.1) Description of sample, (4.2) Evaluation method, and (4.3) Evaluation result will be described. In addition, this invention is not limited at all by these examples.

(4.1) Explanation of sample The following samples 1 and 2 were prepared as the object of tire noise evaluation. Samples 1 and 2 will be described with reference to FIG.

Sample 1 is an existing pneumatic tire in which a circumferential main groove along the tire circumferential direction and a lug groove along the tread width direction are formed. Sample 2 is a pneumatic tire 1 according to the embodiment. Table 1 shows the groove width of the circumferential sub-groove and the ratio of the groove depth to the circumferential main grooves 11, 13, 15 in the pneumatic tire of Sample 2. The depths of the circumferential main grooves of Samples 1 and 2 were both set to 7.5 mm. The groove volume of sample 1 and the groove volume of sample 2 were the same.

(4.2) Evaluation method Using the pneumatic tires of Samples 1 and 2, tire noise was evaluated. Data on tire noise was measured under the following conditions.
・ Tire size: 205 / 55R16
・ Rim size: Standard rim of JATMA 6.5J × 16
・ Internal pressure condition: Standard internal pressure specified by JATMA ・ Load condition: 1 adult male ride ・ Test vehicle: Domestic car sedan ・ Steering stability evaluation: Based on test driver feeling evaluation.
・ Tire noise evaluation: Based on test driver feeling evaluation.
Using the pneumatic tire of Sample 1 as a reference, the steering stability was scored by the 10-point method, and the noise evaluation was scored by the 5-point method (see Table 2).

(4.3) Evaluation results Table 3 shows the evaluation results of the steering stability and the tire noise.

  From the results shown in Table 3, it was found that the tire of sample 2 can reduce the pattern noise as compared with the tire according to sample 1.

(5) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the embodiment of the present invention can be modified as follows. Specifically, the tire may be a tire filled with air or nitrogen gas, or may be a solid tire not filled with air or nitrogen gas. Further, the tire is not necessarily a pneumatic tire, and may be a tire mounted on a vehicle such as a passenger car.

  In the embodiment of the present invention described above, the case where the circumferential main grooves 11, 13, 15 are formed in the tread 10 has been described. However, the number of circumferential main grooves is not limited to three. There may be four.

  In addition, narrow grooves 51 and 52 that are narrower in the tread width direction than the circumferential main grooves 11, 13, and 15 are formed in the center portions in the tread width direction of the first central land portion 21 and the second central land portion 23. Explained. However, a narrow groove may be formed in one of the first central land portion 21 and the second central land portion 23.

  Moreover, in embodiment, the groove depth of the 1st lug grooves 41 and 42 formed in the 1st central land part 21 was demonstrated so that it might be the same. Further, the second lug grooves 43, 44 have been described as having the same groove depth. However, the groove depth D1 of the first lug grooves 41 and 42 may be greater than the groove depth D2 of the second lug grooves 43 and 44, and the depth of the first lug groove 41 and the depth of the first lug groove 42 are: May be different. Further, the depth of the second lug groove 43 and the depth of the second lug groove 44 may be different.

  Further, in the embodiment, the depth D4 of the first circumferential sub-grooves 31a, 31b, 31c, 31d, 31e, and 31f is 0.35 to 0.6 of the depth D3 of the circumferential main grooves 11, 13, and 15. It has been described that the depth D5 of the second circumferential sub-grooves 32a, 32b, 32c, and 32d is 0.20 to 0.60 of the depth D3 of the circumferential main grooves 11, 13, and 15. Further, the first circumferential sub-grooves 31a, 31b, 31c, 31d, 31e, and 31f have been described as having the same depth D4. Further, the second circumferential sub-grooves 32a, 32b, 32c, and 32d have been described as having the same depth D5.

  However, the relationship between the depth D3 of the circumferential main groove and the depth D4 of the first circumferential subgroove 31, D4 / D3 = 0.35 to 0.60, the depth D3 of the circumferential main groove and the second circumferential direction Within the range which satisfies the relationship of the depth D5 of the subgroove 32, D5 / D3 = 0.20-0.60, you may differ individually.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire, 10 ... Tread, 11, 13, 15 ... Circumferential main groove, 21 ... 1st central land part, 23 ... 2nd central land part, 25 ... 1st shoulder land part, 27 ... 2nd shoulder Land part 31 ... 1st circumferential sub groove, 31a-31f ... 1st circumferential sub groove, 32 ... 2nd circumferential sub groove, 32a-32f ... 2nd circumferential sub groove, 41, 42 ... 1st lug Groove, 43, 44 ... second lug groove 51, 52 ... narrow groove

Claims (7)

On the tread that contacts the road surface,
A plurality of circumferential main grooves extending along the tire circumferential direction;
A pair of central land portions formed through the tire equator line by being partitioned by the plurality of circumferential main grooves, and a pair of shoulder land portions formed on the outer side in the tread width direction than the pair of central land portions. A tire having
The pair of central land portions are:
A first central land portion located on one side in the tread width direction from the tire equator line;
A second central land portion located on the other side in the tread width direction from the tire equator line,
The pair of shoulder land portions are:
A first shoulder land portion formed on a shoulder portion on one side in the tread width direction from the tire equator line;
A second shoulder land portion formed on the shoulder portion on the other side in the tread width direction from the tire equator line,
A plurality of first lug grooves extending in the tread width direction and aligned along the tire circumferential direction are formed in the first central land portion,
A plurality of second lug grooves extending in the tread width direction and aligned along the tire circumferential direction are formed in the second central land portion,
The depth of the first lug groove is deeper than the depth of the second lug groove,
A plurality of first circumferential sub-grooves extending along the tire circumferential direction are formed in the first shoulder land portion,
A plurality of second circumferential sub-grooves extending along the tire circumferential direction are formed in the second shoulder land portion,
The width in the tread width direction of the first circumferential sub-groove and the second circumferential sub-groove is narrower than the width in the tread width direction of the circumferential main groove,
The number of the first circumferential sub-grooves is greater than the number of the second circumferential sub-grooves.   The tire according to claim 1, wherein at least three circumferential main grooves are formed in the tread. At least one of the plurality of first circumferential sub-grooves is formed on the outer side of the tread width direction outer ground end in a state where the tire is in contact with the road surface,
3. The tire according to claim 1, wherein at least one of the plurality of second circumferential sub-grooves is formed on an outer side than a grounding end portion on an outer side in a tread width direction in a state where the tire is grounded.   4. The groove width in a direction orthogonal to the direction in which the first lug groove extends and the groove width in a direction orthogonal to the direction in which the second lug groove extends are 1 mm to 2 mm. The described tire. The depth of the first circumferential sub-groove is 0.35 to 0.6 of the depth of the circumferential main groove,
The tire according to any one of claims 1 to 4, wherein a depth of the second circumferential sub-groove is 0.20 to 0.60 of a depth of the circumferential main groove.   Of the plurality of second circumferential sub-grooves, the distance between the inner second circumferential sub-groove located on the innermost side in the tread width direction and the second circumferential sub-groove adjacent to the inner second circumferential sub-groove is The tire according to any one of claims 1 to 5, which is wider than an interval between the other second circumferential sub-grooves.   7. The thin groove having a narrower width in the tread width direction than the circumferential main groove is formed in the center of the first central land portion or the second central land portion in the tread width direction. The tire according to claim 1.

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