JP2010260471A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire lowering the generation of a noise without spoiling drainage performance on a wet road surface. <P>SOLUTION: Circumferential grooves are arranged on a tread surface 1. Land parts are formed in rows of blocks formed of a plurality of blocks, and comprise land parts adjacent to the inner side of the tread width direction of the outermost circumferential groove 2. The groove wall on the tire equatorial plane side of the outermost circumferential groove 2 of the tread surface 1 is an uneven wall surface extending in a tread circumferential direction in a crank-like fashion in an expansion planar view of the tread surface 1, and the groove wall on the outer side of the tread width direction is formed in a linear fashion. A region for partitioning the blocks formed in an adjacent region of the recessed wall surface to the protruded wall surface is an inclined wall surface 13 which is inclined in a direction narrowing the circumferential groove, and terminates halfway at the bottom width of the groove. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire in which noise generated due to air column resonance in a circumferential groove is reduced and dispersed without impairing drainage performance on a wet road surface.

  In a pneumatic tire, in order to achieve both drainage performance and steering stability, it is common to arrange a circumferential groove extending in the tread circumferential direction and a lateral groove extending in a direction crossing the circumferential groove on the tread surface. . In this type of tire, drainage in the front-rear direction of the tire can be performed by the circumferential groove, and drainage to the side of the tire can be performed by the lateral groove.

  In such a tire, when the tire rolls on the ground, the air in the circumferential groove is oscillated and resonated in a tubular space defined by the circumferential groove and the road surface. However, there is a problem that it accounts for a large proportion of pattern noise.

  Thus, for example, Patent Documents 1 to 3 disclose tires intended to reduce generated noise by changing the groove width of the circumferential groove to disperse the air column resonance frequency of the air in the groove.

  However, although the tires described in Patent Documents 1 to 3 can reduce the generated noise, the groove volume of the circumferential groove is reduced by partially narrowing the groove width of the circumferential groove. Further improvement of drainage performance on wet road surfaces has been desired.

JP-A-7-195910 JP-A-3-136909 JP 2006-82586 A

  Therefore, the present invention provides a pneumatic tire in which generated noise is reduced without impairing drainage performance on a wet road surface.

  The pneumatic tire according to the present invention is provided with at least a pair of circumferential grooves located on the tread surface with the tire equatorial plane interposed therebetween, and an outermost circumferential groove positioned farthest from the tire equatorial plane and a circumferential groove adjacent thereto. The land portion partitioned between the two is a block row composed of a plurality of blocks, and is composed of a land portion adjacent to the innermost side in the tread width direction of the outermost peripheral groove, and the outermost peripheral groove of the tread surface is The groove wall on the tire equatorial plane side is a concave and convex wall surface that extends in a crank shape in the tread circumferential direction in a development plan view of the tread surface, and the groove wall on the outer side in the tread width direction is linear, and the convex wall surface of the concave wall portion A region that divides a block formed in a region adjacent to the portion is an inclined wall surface that is inclined in the direction of narrowing the circumferential groove and ends in the middle of the groove bottom width.

  Here, the “inclined wall surface” can be formed not only by a flat inclined surface that is linearly inclined in a side view but also by an inclined surface that is a convex or concave curved surface.

  In such a tire, the circumferential grooves are more preferably arranged symmetrically across the tire equatorial plane.

  In the pneumatic tire of the present invention, the groove wall on the tire equator surface side of the outermost circumferential groove located farthest from the tire equator surface of the tread surface extends in a crank shape in the tread circumferential direction in a development plan view of the tread surface. By making the groove wall on the outer side in the tread width direction straight and changing the groove volume sequentially, the air column resonance frequency of the air in the circumferential groove can be dispersed, resulting in a reduction in generated noise. At the same time, the shoulder land portion located on the outer side of the outermost circumferential groove in the tread width direction protrudes into the outermost circumferential groove, and it is possible to suppress the deterioration of uneven wear resistance by locally reducing the rigidity of the portion. .

In addition, the area defining the block formed in the area adjacent to the convex wall surface portion of the concave wall surface portion is an inclined wall surface that is inclined in the direction of narrowing the circumferential groove and ends in the middle of the groove bottom width, Circumferential groove from the concave wall surface side of the peripheral groove to the convex wall surface side or in the opposite direction by effectively reducing the flow resistance of drainage through the peripheral groove by preventing sudden shrinkage and rapid expansion It is possible to improve the property of making the flow of water in the interior sufficiently smooth, and to prevent the drainage from deteriorating due to a sudden change in the groove width. As a result, a decrease in the wet performance of the tire can be effectively prevented.
Thus, with this pneumatic tire, it is possible to achieve both a reduction in generated noise and a reduction in wet performance in particular.

It is a tread pattern which shows one embodiment of the pneumatic tire of the present invention. (A) is AA sectional drawing of FIG. 1, (b) is BB sectional drawing of FIG. (A)-(c) is a tread pattern which shows one Embodiment of the conventional pneumatic tire.

Hereinafter, the pneumatic tire of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a developed plan view of a tread surface showing an embodiment of the pneumatic tire of the present invention. 2A is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 2B is a cross-sectional view taken along the line BB in FIG.

  In the figure, 1 is a tread surface, 2 is a circumferential groove extending in a straight line in the tread circumferential direction at a position that is equally spaced from the tire equator CL, and 3 is a tread surface of the tread surface 1. Each tread edge is shown.

  In the figure, for example, in a central land portion 4 defined between two circumferential grooves 2 that are symmetrically located across the tire equatorial plane CL, in a substantially letter shape toward the circumferential groove 2 in the vicinity of the tire equatorial plane CL. A plurality of bent grooves 5 having a steeply inclined groove portion 5a and a gently inclined groove portion 5b that are bent and open into the same circumferential groove 2 at both ends, and an intermediate portion of the gently inclined groove portion 5b of the bent groove 5 A plurality of curved grooves 6 that branch and curve in the vicinity of the tire equatorial plane CL and open to the circumferential groove 2 across the steeply inclined groove portion 5a of the bent groove 5 are disposed. In the central land portion 4 near the tire equator plane CL, the steeply inclined groove portions 5a of the bent groove 5 extending across the tire equator plane CL communicate with each other. The horizontal grooves 7 and the curved grooves 6 in the vicinity of the curved portions of the curved grooves 6 are disposed in the same manner as in the downwardly straight linear grooves 8.

  By the way, a substantially triangular first block 9 defined by the bent portion of the bent groove 5 and the curved groove 6 is formed on both side portions thereof, and the bent groove is adjacent to the tread circumferential direction of the first block 9. The substantially triangular second block 10 defined by the five steeply inclined groove portions 5 a and the curved groove 6, and the steeply inclined groove portion 5 a and the curved portion of the bent groove 5 adjacent to the second block 10 in the tread circumferential direction. A third block 11 defined by the groove 6, and a block row including a fourth block 12 defined by the bent groove 5, the curved groove 6 and the lateral grooves 7, 8 in the vicinity of the tire equatorial plane CL. Form.

  Further, in this tire, the groove wall on the tire equatorial plane side of the circumferential groove 2 of the tread surface 1 is a convex wall surface extending in a crank shape in the tread circumferential direction in the development plan view of the tread surface 1, and the groove on the outer side in the tread width direction. While making the wall straight, the block formed in the adjacent area of the concave wall surface part to the convex wall surface part, in FIG. 1, the area defining the first block 9 is inclined to narrow the circumferential groove 2. In FIG. 1, the inclined wall surface 13 protrudes toward the opposing wall side of the circumferential groove 2 and ends in the middle of the groove bottom width.

  Further, such an inclined wall surface 13 can be provided with a skirt portion on the inclined wall surface 13 whose height gradually decreases in the tread circumferential direction, as well as being stepped down. It is possible to further prevent the drainage from being deteriorated due to a sudden change in the groove width of the groove 2.

  The first block 9 is provided with two sipes 14 extending from the steeply inclined groove part 5a of the bent groove 5 in a direction substantially perpendicular to the steeply inclined groove part 5a. And the other sipe extending in the vicinity of the bent portion of the bent groove 5 is terminated in the first block 9. The block 9 is provided with a substantially straight sipe 15 extending from the steeply inclined groove portion 5a to the curved groove 6, and the block portions divided by the sipe 14 and 15 are substantially equal in size. The second block 10 includes two sipes 16 extending from the steeply inclined groove portion 5a of the bent groove 5 in a direction substantially perpendicular to the steeply inclined groove portion 5a and ending in the block 10, The block 10 is provided with a substantially straight sipe 17 extending from the curved groove 6 to the circumferential groove 2.

A chamfered portion 18 in which the land height gradually decreases toward the circumferential groove 2 is provided at an acute corner between the circumferential groove 2 and the steeply inclined groove portion 5 a of the bent groove 5 of the second block 10.
Moreover, the chamfered part 19 which inclines in the direction which reduces the land part height toward the steeply inclined groove part 5a is provided in the part at the side of the steeply inclined groove part 5a of the 1st block 9 and the 2nd block 10.

The third block 11 includes three sipes extending from the steeply inclined groove portion 5a of the bent groove 5 toward the curved groove 6 and extending across the third block 11 substantially perpendicular to the curved groove 6. 20, the sipe 20 from the circumferential groove 2, and a sipe 21 that extends from the circumferential groove 2 in parallel with the sipe 20 and ends in the block 11.
Further, a chamfered portion 22 in which the land portion height gradually decreases toward the circumferential groove 2 is provided at a corner portion of the third block 11 adjacent to the chamfered portion 18.

  Further, the fourth block 12 includes two sipes 23 that are inclined in the tread circumferential direction from the steeply inclined groove portion 5a of the bent groove 5 and extend almost in parallel toward the tire equatorial plane CL. A substantially straight sipe 24 is disposed inclining in the circumferential direction toward the tire equatorial plane CL. Further, a substantially triangular chamfered portion 25 is provided on the side of the curved groove 6 where the sipe 24 of the fourth block 12 is disposed, and is inclined toward the curved groove 6 in a direction of gradually decreasing the land portion height.

In this tire, by providing a circumferential groove 2 extending in the tread circumferential direction in the tread tread surface 1, the drainage in the front-rear direction of the tread ground surface is ensured, and between the two circumferential grooves 2. By providing the central land portion 4 with the bent grooves 5, the curved grooves 6 and the lateral grooves 7 and 8, the water present in the central land portion 4 is mainly drained smoothly to the side of the central land portion 4. Can be done.
In addition, the chamfered portions 18, 19, 22, and 25 increase the rigidity of the tip portion, prevent crushing at the time of grounding, and in turn, escape deformation into the groove, improve drainage, Smooth grounding can be ensured, noise can be reduced, and uneven wear resistance can be improved.

In the shoulder land portion 26 formed between the circumferential groove 2 and the tread tread surface end 3, a lateral groove 27 extending substantially parallel to the tread circumferential direction from the circumferential groove 2 toward the tread tread surface end 3 is provided at a predetermined interval. A plurality of blocks are arranged to form a block row. Then, three sipes 28 extending from the circumferential groove 2 toward the tread surface end 3 are disposed between the lateral grooves 27 adjacent to each other in the tread circumferential direction. A cutout portion 29 that is stepped down toward the circumferential groove 2 is provided on the circumferential groove 2 side of the sipe 28 at the center.
As a result, it is possible to adjust the rigidity of the shoulder land portion 26 between the circumferential groove 2 and the tread tread edge 3 and the drainage to the side, and improve steering stability and wet braking performance. This is not essential.

  Further, when viewed from the entire tread surface, a pattern that is point-symmetric with respect to the tire equatorial plane CL is preferable, but in the present invention, a so-called directional pattern that is line-symmetric can also be used.

  More preferably, in this tire, the circumferential grooves 2 are symmetrically arranged with the tire equatorial plane CL in between, so that the circumferential grooves 2 caused by the generation of air column resonance can be minimized. Further, the vicinity of the tire equatorial plane CL becomes a rib base, so that the rigidity can be enhanced, and the outer side can improve the braking performance and drainage by the circumferential groove 2.

(Noise)
Next, a tire according to the present invention having a structure as shown in FIG. 1 was prototyped, tire size: P265 / 7OR17 (TRA standard, P TYPE TIRES USED ON PASSENGER CAR AND STATIONWAGONS), rim size: 17 × 8J, tire pressure : At 210 kPa, noise characteristics were evaluated with a noise meter 50 cm lateral from the tire on a drum at 80 km / h. In the evaluation, the A characteristic (dB) and the peak sound pressure level are indexed, and the results are shown in Table 1. In the evaluation, the comparative example tire 1 is set to 100, and the smaller the numerical value, the better the performance.
The comparative example tire 1 was not provided with an uneven wall surface in the circumferential groove as shown in FIG. The comparative example tire 2 has an uneven wall surface on the outer side in the tread width direction of the circumferential groove as shown in FIG. The comparative tire 3 was an inclined wall surface in which the land height did not gradually decrease as shown in FIG.
In the present invention, since the tire structure other than the tread surface is not required to be modified, it is almost the same as the structure of the conventional pneumatic tire.

(Uneven wear resistance)
For each of Example Tire 1 and Comparative Example Tire 1 to Comparative Example Tire 3, the test vehicle: GM Sierra 250OHD, after running 16000 km on the test course, the amount of step difference between the shoulder block stepping part and the kicking part ( mm), and the results are shown in Table 1.
In the evaluation, the comparative tire 1 is set to 100, and the smaller the numerical value, the better the performance.

(Snow surface braking)
For each of the example tire and the comparative example tire 1 to the comparative example tire 3, the snowy road surface was indexed by Toyota Motor Hilux Surf at an initial speed of 40km / h, and the stop distance (mm) at full brake was indexed. Table 1 shows.
In the evaluation, the comparative tire 1 is set to 100, and the smaller the numerical value, the better the performance.

(Wet road surface braking)
For each of the example tire, comparative tire 1 to comparative tire 3, the wet road surface was indexed by Toyota Motor Hilux Surf, initial speed 40 km / h, and the stopping distance (mm) at full brake was indexed. It is shown in 1.
In the evaluation, the comparative tire 1 is set to 100, and the smaller the numerical value, the better the performance.

  From the results shown in Table 1, the example tires can improve the wet road surface braking performance without reducing noise, uneven wear resistance, and snow road surface braking performance as compared with the comparative tires 1 to 3.

DESCRIPTION OF SYMBOLS 1 Tread tread 2 Circumferential groove 3 Tread tread edge 4 Central land part 5 Bent groove 5a Steeply inclined groove part 5b Slowly inclined groove part 6 Curved groove 7, 8, 27 Lateral groove 9 First block 10 Second block 11 Third block 12 First Four blocks 13 Inclined wall surface 14, 15, 16, 17, 20, 21, 23, 24, 28 Sipe 18, 19, 22, 25 Chamfered portion 26 Shoulder land portion 29 Notched portion CL Tire equator surface

Claims (2)

At least a pair of circumferential grooves located on the tread tread with the tire equatorial plane in between, and a land portion that is partitioned between the outermost circumferential groove located farthest from the tire equatorial plane and the adjacent circumferential groove In a pneumatic tire composed of a land portion adjacent to the inner side in the tread width direction of the outermost circumferential groove, a block row composed of a plurality of blocks,
In the tread tread surface, the groove wall on the tire equator surface side of the outermost circumferential groove is a concave wall surface extending in a crank shape in the tread circumferential direction in a development plan view of the tread surface, and the groove wall on the outer side in the tread width direction is made straight. The region defining the block formed in the region adjacent to the convex wall portion of the concave wall portion is an inclined wall surface that is inclined in the direction of narrowing the circumferential groove and ends in the middle of the groove bottom width. Pneumatic tires.   The pneumatic tire according to claim 1, wherein the circumferential grooves are arranged symmetrically across the tire equatorial plane.

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