JP2010070045A - Tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for attaining road noise reduction in a tire having circumferential direction sub-grooves that intermittently extend in a circumferential direction of a tread. <P>SOLUTION: This tire includes the plurality of circumferential direction sub-grooves that intermittently extend in the circumferential direction of the tread under arrangement where the grooves adjacent to each other in the circumferential direction partially overlap with each other in the tread width direction at the tread, and at least two lateral grooves for connecting between the circumferential direction sub-grooves adjacent to each other at the overlap part. In the tire, a cross vent for connecting the one side wall of the groove to the other side wall is provided on at least one of the lateral grooves. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tire, and particularly to a tire with reduced road noise.

It is customary to ensure drainage mainly by arranging a plurality of circumferential grooves extending in the tread circumferential direction on the tread surface of the tire. Furthermore, in recent years, circumferential sub-grooves that extend in an inclined direction with respect to the circumferential groove and terminate in the land section defined by the circumferential groove are arranged to further improve drainage performance and the land section. A tread pattern that is intended to ensure rigidity has been proposed. For example, Patent Document 1 describes an inclined lug groove corresponding to the circumferential sub-groove.
JP 2006-123706 A

  In such a tread pattern, that is, a tire having a circumferential sub-groove extending intermittently in the circumferential direction of the tread, the occurrence of road noise becomes a new problem.

  Therefore, the present invention intends to provide means for realizing road noise reduction in a tire having the specific tread pattern.

  The inventor has intensively investigated the cause of noise generation in tires having circumferential sub-grooves extending intermittently in the circumferential direction of the tread, and elucidated that the rubber thickness of the tread surface is uneven in the circumferential direction. Arrived. Further, when the cause of the uneven rubber thickness in the circumferential direction was examined, when the circumferential sub-grooves were arranged, in the portion where the grooves partially overlapped in the tread width direction, It was found that the fluid rubber stays and the thickness of the tread rubber after vulcanization becomes uneven in the circumferential direction, resulting in deterioration of tire uniformity and noise generation.

This invention is made | formed based on the above knowledge, The summary structure is as follows.
(1) The tread has a plurality of circumferential sub-grooves extending intermittently in the circumferential direction under an arrangement in which grooves adjacent in the circumferential direction partially overlap in the tread width direction. In a tire having at least two lateral grooves that connect between adjacent circumferential sub-grooves, a cross vent that connects one side wall and the other side wall of the groove is provided on at least one of the lateral grooves. Tire characterized by.

(2) The tire according to (1), wherein the cross vent is disposed on or near a tread surface.

  ADVANTAGE OF THE INVENTION According to this invention, the uniformity of a tire can be improved and generation | occurrence | production of road noise can be suppressed.

Hereinafter, the tire of the present invention will be described in detail with reference to the drawings.
An example of a tread pattern according to the present invention is shown in FIG. In the illustrated tread pattern, the tread 1 is divided into three rows of land portions 3a, 3b, and 3c by two circumferential grooves 2a and 2b extending in the circumferential direction of the tread and a tread end E. Further, in the land portion row 3a on one side, lateral grooves 4a and 4b extending in the tread width direction between the circumferential groove 2a and the tread end E are alternately arranged in the circumferential direction, and the land portion row 3c on the other side is arranged. The horizontal grooves 4c and sipes 4d extending in the tread width direction between the circumferential grooves 2b and the tread ends E are alternately arranged in the circumferential direction.

  The remaining land portion 3b is open to the circumferential groove 2a, and the lateral groove 5a is inclined toward the circumferential groove 2b and extends into the land portion 3b toward the circumferential groove 2b. A lateral groove 5b that extends toward the circumferential groove 2 and inclines with respect to the circumferential groove and extends into the land portion 3b. These lateral grooves 5a and 5b are connected to circumferential grooves on the opposite side to the opening side through sipes 6a and 6b extending from the terminal portion in the land portion 3b.

  Here, the land portion 3b is further provided with a plurality of circumferential sub-grooves 7 extending intermittently in the tread circumferential direction, and the grooves 7 adjacent to each other in the circumferential direction partially overlap each other in the tread width direction. It is important to have below. Accordingly, blocks 30 and 31 are defined in the overlapping portion of the circumferential sub-groove 7 by the circumferential sub-groove 7 and the lateral grooves 5a and 5b described above. The tire of the present invention does not need to be limited to the illustrated example except that the tread pattern includes the circumferential sub-groove 7 and the lateral grooves 5a and 5b.

The illustrated circumferential sub-grooves 7 meander gently in the circumferential direction of the tread and have a shape extending in an S shape. However, the overall shape is not limited to the illustrated example, for example, a zigzag shape or a linear shape. . As shown in FIG. 1, the circumferential sub-grooves 7 adjacent to each other in the tread circumferential direction may have an overlapping portion W that partially overlaps in the tread width direction.
This overlapping portion W is preferably in the range of S to 2S, when a portion other than the overlapping portion W of the circumferential sub-groove 7 is a non-overlapping portion S. This is because, within this range, the circumferential block rigidity and drainage performance related to brake performance are in an appropriate balance.

  Further, the lateral grooves 5a and 5b may be grooves extending between the grooves 7 in the overlapping portion W of the circumferential sub-groove 7, and are not necessarily inclined with respect to the circumferential grooves 2a and 2b. You may open to the circumferential groove | channel 2a or 2b, without providing the sipe 6a and 6b in the side.

In the above-described tread pattern, it is important to provide a cross vent 8 that connects one side wall and the other side wall of at least one of the lateral grooves 5a and 5b. In FIG. 1, the case where the cross vent 8 is provided in both the lateral grooves 5a and 5b and the case where it is provided in the lateral groove 5b are shown together.
The cross vent 8 is a rubber layer straddling, for example, between one side wall and the other side wall of the lateral groove 5b at a position spaced from the groove bottom, as shown in FIG. 2 along the line II-II in FIG. In the example of FIG. 2, the surface of the cross vent 8 is provided so as to coincide with the tread surface. As shown in FIG. 3, the surface of the cross vent 8 may be disposed inside the lateral groove 5b. In short, the cross vent 8 is interposed between one side wall and the other side wall of the lateral groove. Just do it.

Now, in the land portion 3b in which the circumferential sub-groove 7 is arranged, the negative ratio in the overlapping portion W and the non-overlapping portion S (when the target groove is limited to the circumferential sub-groove 7) is the same as that in the non-overlapping portion S. It becomes large at the portion W. If this is replaced with a mold used for vulcanization molding of tires, the proportion of the mold convexities that form grooves in the mold is higher in the overlapping portion W than in the non-overlapping portion S. Since this mold convex part acts like a weir that hinders the flow of rubber during vulcanization molding, the flow of rubber is naturally limited in the overlapping part W than in the non-overlapping part S. Since the overlapping portion W is a portion where the mold convex portion overlaps in the tread width direction, the flow of rubber in the tread width direction is particularly disturbed. Further, the overlapping portion W is provided with transverse grooves 5a and 5b, which also become mold convex portions during vulcanization molding, and as a result, the overlapping portion W is divided into two sections ( Block in the tire) occurs, and the rubber is surely retained here.
Then, as a result of the difference in rubber flow between the overlapping portion W and the non-overlapping portion S, the thickness of the tread rubber at the overlapping portion W (hereinafter simply referred to as rubber thickness) in the tire after vulcanization molding is non- It becomes thicker than the rubber thickness at the overlapping portion S.

Therefore, by providing the cross vent 8, the rubber flow during vulcanization molding is equalized between the non-overlapping portion S and the overlapping portion W, and with this, the overlapping portion W in the tire after vulcanization molding is performed. And the non-overlapping portion S are prevented from having a rubber thickness difference, and variations in the rubber thickness in the circumferential direction are suppressed.
That is, when the cross vent 8 is replaced with a mold used for vulcanization molding, it is a mold concave portion and a portion that becomes a path for rubber. Accordingly, the provision of the cross vent 8 in either of the lateral grooves 5a and 5b means that a rubber path to the outside of the section is provided in the two sections surrounded by the mold convex portions in the overlapping portion W, and particularly the tread circumference. The flow of rubber in the direction is ensured. As a result, it is possible to equalize the rubber flow during vulcanization molding between the non-overlapping portion S and the overlapping portion W.

  In particular, the cross vent 8 is preferably provided such that its surface coincides with the tread surface, as shown in FIG. Because, during vulcanization molding, the rubber flow between the blocks 30 and 31 sandwiching the transverse groove 5b is performed through the cross vent 8, so that if the surface of the cross vent 8 and the tread surface coincide, Since the rubber flow can be realized without stagnation, particularly the rubber flow to the corner portion 9 of the block is reliably ensured.

  The cross vent 8 is preferably provided with a width of 2 mm to 3 mm in the width direction of the lateral groove. This is because if less than 2 mm, the fluidity of the rubber cannot be ensured, and if it exceeds 3 mm, the cross vent is difficult to break during vulcanization, and there is a possibility that the block end is chipped.

  Furthermore, the total width of the cross vent 8 is preferably about ½ of the block width. This is to allow the rubber to flow efficiently while ensuring the drainage of the groove.

A tire having the tread pattern shown in FIG. 1 with the specifications shown in Table 1 was manufactured in a size 215/45 R17. Each prototype tire was investigated for uniformity and noise characteristics. The results are also shown in Table 1.
The uniformity has 18 overlapping portions W on the tread circumference, so the prototype tire adjusted to an internal pressure of 210 kPa is pressed against the indoor drum so as to have a load of 3.92 kmN, and a speed of 80 km / This is an evaluation of an 18th-order component of the radial force deflection when rotated at h.

  The noise characteristics are because the prototype tire is mounted on four wheels of a vehicle and the sound when traveling at 80 km / h is measured with a measuring instrument in the vehicle, and there are 18 overlapping portions W on the circumference. The 18th-order component of sound is evaluated.

FIG. 3 is a partial development view of a tread showing a tread pattern of a tire according to the present invention. It is sectional drawing of the cross vent part which follows the II-II line | wire of FIG. It is sectional drawing of a cross vent part.

Explanation of symbols

1 tread 2a, 2b circumferential groove 3a, 3b, 3c land portion row 4a, 4b, 4c transverse groove 4d sipe 5a, 5b transverse groove 6a, 6b sipe 7 circumferential sub groove 8 cross vent 30, 31 block E tread end

Claims (2)

  The tread has a plurality of circumferential sub-grooves extending intermittently in the circumferential direction under an arrangement in which grooves adjacent to each other in the circumferential direction partially overlap in the tread width direction. In a tire having at least two lateral grooves extending between adjacent circumferential sub-grooves, at least one of the lateral grooves is provided with a cross vent that connects one side wall and the other side wall of the groove. Tire.   The tire according to claim 1, wherein the cross vent is disposed on or near a tread surface.

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