JP3203057B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of reducing noise while maintaining grip performance, particularly running performance on ice and snow.

[0002]

2. Description of the Related Art For example, a tire running on rough terrain, on ice, or on snow is surrounded by a plurality of grooves arranged in the tire circumferential direction and in a direction intersecting the circumferential direction in order to enhance grip on a tread surface. A block pattern composed of blocks is formed.

When traveling on ice, snowy roads or soft roads,
While the block enhances the grip performance, the groove efficiently drains water adhering to the tread surface, makes the contact between the tread surface and the road surface denser, and increases the frictional resistance between both surfaces, so that the grip performance in rainy weather That is, the wet grip performance is enhanced.

[0004]

On the other hand, due to the formation of the groove, the compressed air is suddenly discharged through the columnar groove each time the tread surface comes into contact with the ground during running. Tire noise such as noise and noise generated by the vibration of the block is generated. As vehicles have become more sophisticated and more sophisticated, tires have become more strictly required to suppress tire noise in addition to improving grip performance.

To reduce the noise, it is conceivable to make the grooves, particularly the lateral grooves, shallow. However, the shallow grooves increase the rigidity of the block, and deteriorate the grip performance on icy and snowy roads.

As described above, the improvement in grip performance and the suppression of noise are in a trade-off relationship, and the development of a tread pattern for a tire that overcomes this problem has been an important issue in tire technology. Has been made.

For example, Japanese Patent Laid-Open Publication No. Hei 2-14905 attempts to solve the above-mentioned problem by using an inclined groove which is inclined at a relatively small angle and comes into contact with a ground plane. However, if the angle of inclination of the lateral groove is small, the rigidity of the tread is reduced, leading to a reduction in steering stability performance, and the groove in contact with the ground contact surface tends to lack traction performance on a wet road surface. Has not yet been fully resolved.

As a result of repeated studies to solve the above problems, the inventor has found that a protrusion is provided at the open end of the lateral groove, and a part of the air column resonance sound flowing through the lateral groove is insulated, thereby lowering the grip performance. The present inventors have found that noise can be reduced without causing the present invention to complete the present invention.

An object of the present invention is to provide a pneumatic tire that can reduce running noise of a tire while maintaining grip performance, particularly running performance on icy and snowy roads, and can be suitably used as a snow tire or a tire for running on uneven terrain. I have.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a plurality of vertical grooves extending in a tire circumferential direction on a tread portion, and a horizontal groove and a vertical groove extending in a direction intersecting the vertical grooves and having both ends opened by the vertical grooves. A pneumatic tire having a block pattern provided with outer lateral grooves having both ends opened at a tread edge and a tread edge, wherein a noise-reducing projection protruding from a groove bottom is provided near each of the lateral grooves and at least one opening end. At the same time, the protrusion has a length in the groove direction at the groove bottom of the horizontal groove of 0.3 mm of the groove length of the horizontal groove.
The width is 0.6 times or less and 2 mm or more of the width of the horizontal groove, the height is 0.4 times or less of the groove depth of the horizontal groove and 2 mm or more, and the width of the top of the projection is in the direction of the groove. A pneumatic tire having a length of at least 2 mm.

[0011]

The block pattern formed by the vertical groove and the horizontal groove is formed in the tread portion. The gripping property is maintained by this block when traveling on icy and snowy roads. In addition, since the horizontal groove is open at both ends at the vertical groove or tread edge, water adhering to the ground contact surface can be efficiently drained by the horizontal groove, and the contact between the tread surface and the road surface is made dense and the rolling friction resistance is increased. In addition, grip performance in rainy weather, that is, wet grip performance can be improved.

The inner and outer lateral grooves are provided with protrusions located near the opening ends and protruding from the groove bottom. This suppresses the overspeed of air passing through the lateral groove, reduces the occurrence of air column resonance,
It can reduce the noise caused by running.

When the length of the protrusion in the groove direction exceeds 0.3 times the groove length of the lateral groove, when the width dimension is larger than 0.6 times the groove width of the lateral groove, and The height is 0.
In any case, such as when it exceeds four times, the noise is reduced, but the rigidity of the block is increased and the grip performance is lowered, which is not preferable.

Conversely, if the length in the groove direction is less than 4 mm, the width dimension and the height are less than 2 mm, and if the length in the groove direction at the top of the projection is less than 2 mm, the air passing through the lateral groove is controlled. As a result, the air column sound generated from the lateral groove is not significantly reduced, and the suppression of noise becomes insufficient.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. In the figure, a pneumatic tire 1 includes a plurality of vertical grooves 3 extending in a tire circumferential direction on a tread portion 2 and lateral grooves 4 extending in a direction intersecting the vertical grooves 3.

In the present embodiment, the longitudinal groove 3 is a central longitudinal groove 3A located on the tire equator, and a pair of longitudinal grooves arranged between the central longitudinal groove 3A and the tread edge E. 3B, 3B
The horizontal groove 4 has a central vertical groove 3A and a lateral vertical groove 3B at both ends thereof.
B and the tread edge E are provided with an outer lateral groove 6 which is open, so that the tread portion 2 has these vertical grooves 3.
A block pattern consisting of blocks B surrounded by... Is formed.

In this embodiment, as shown in FIG. 1, a horizontal narrow groove 11A connecting the central vertical groove 3A and a vertical vertical groove 3B, and a vertical vertical groove connecting the horizontal narrow grooves 11A in the circumferential direction. Narrow groove 11
B is established. In this embodiment, the vertical grooves 3 are linear grooves, and the horizontal grooves 5, 6 are formed as curved grooves inclined with respect to the tire axis.

Further, the pneumatic tire 1 has sidewall portions 13 extending radially inward from the tread portion 2 and bead portions 15 located at radially inner ends of the sidewall portions 13. Have, each bead part 1
A toroidal carcass 17 that passes through the sidewall portions 13, 13 and the tread portion 2 is bridged between the bead cores 16 provided in the tread portions 5, 15, and a belt layer 19 is disposed radially outward and in the tread portion 2. I have arranged.

The carcass 17 is a so-called radial or semi-radial array in which carcass cords are arranged at an angle of 60 to 90 degrees with respect to the equator C of the tire in this embodiment. , Rayon, aromatic polyamide or other organic fiber cords are employed.

In this embodiment, two belt plies are arranged on the belt layer 19 from the carcass 17 side to the radial outside of the tire. Further, the belt layer 19 includes belt cords which are arranged on each belt ply at an angle and intersect with each other. The belt cords are, like the carcass 17, other than organic fiber cords such as nylon, polyester, rayon and aromatic polyamide. , Steel cord is used.

The vertical groove G can be formed as a zigzag groove or a wavy groove in addition to a straight groove as in this embodiment.

In the present embodiment, the vertical groove 3 and the horizontal groove 4 have their groove depths GH set to the tread lines E, E of the tread portion 2.
Of the tread width TW, which is the distance in the tire axial direction between
The groove width GW is set to 0.04 to 0.12 times the tread width TW while being set to 8 to 0.16 times.

The horizontal groove 5 protrudes from the bottom 7 of the horizontal groove 5 in the vicinity of the opening ends F, F on both sides which are respectively opened to the central vertical groove 3A and the side vertical groove 3B. Protrusions 9, 9 are provided. On the other hand, the outer vertical groove 6 has
The protruding portion 9 having the above-described configuration is provided near one opening end F that opens to B.

The length L of the lateral grooves 5 and 6 where the projections 9 are located at the groove bottom 7 in the groove direction is 0.3 times or less the groove length GL of the lateral grooves 5 and 6, and 4 mm, and the width W is 0.6 times or less of the groove width GW of the lateral grooves 5 and 6 and 2
mm, and the height H of the protrusion 9 from the groove bottom 7 is not more than 0.4 times the groove depth GH of the lateral grooves 5 and 6 and not less than 2 mm. Further, the protrusion 9 has a length L1 in the groove direction at the top 10 of at least 2 mm.

In the pneumatic tire of the present invention,
The vertical groove may be formed as a zigzag groove continuously bent in a letter shape, and the inner and outer horizontal grooves may be formed so that the groove width gradually increases toward the tread edge. It can be transformed into the embodiment.

[0026]

[Specific Example] A tire having a tire size of 225 / 70R15 and having the structure shown in FIG. 1 was prototyped according to the specifications (Examples 1 to 3) shown in Table 1, and its performance was tested. In addition, the conventional tire (Comparative example 1) which does not provide a projection part, and the tires (Comparative examples 2
A test was also conducted for 4), and the performance was compared.

The test conditions are as follows. B) Noise test Each test tire was mounted on a small four-wheel drive vehicle (displacement 1600c).
c), the vehicle was run on a specific road noise test road, and the noise pressure level of the noise was measured on the road noise measurement road. The larger the value, the lower the noise.

B) Snow test Attached to the same vehicle as in item a), sudden braking was applied on ice at an outside temperature of -5 ° C., and the braking distance was measured. displayed. The higher the value, the better. Table 1 shows the test results.

[0029]

[Table 1]

[0030]

As described above, the pneumatic radial tire according to the present invention is provided with a vertical groove or a horizontal groove having both ends opened by the vertical groove and the tread edge, and a groove bottom near at least one open end of the horizontal groove. With the projections that protrude from the groove and regulate the length, width, and height in the groove direction, noise generated during running can be reduced while maintaining grip performance, especially running performance on ice and snow. Or, it can be suitably adopted as a tire for running on uneven terrain.

[Brief description of the drawings]

FIG. 1 is a developed plan view showing a tread pattern of a pneumatic tire of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an enlarged perspective view showing an opening and a protrusion of a lateral groove.

[Description of Signs] 2 Tread portion 3 Vertical groove 4 Lateral groove 5 Lateral groove 6 Outer lateral groove 7 Groove bottom 9 Projection 10 Top E Tread edge F Open end GH Lateral groove depth GL Lateral groove length GW Lateral groove Groove width H Height L Length L1 Top length W Width

Claims (1)

(57) [Claims] 1. A plurality of vertical grooves extending in a circumferential direction of a tire on a tread portion, and a horizontal groove extending in a direction intersecting the vertical grooves and having both ends opened by the vertical grooves. A pneumatic tire having a block pattern provided with outer lateral grooves to be provided, wherein the lateral grooves and at least one of the opening ends are provided with noise-reducing projections protruding from the groove bottom in the vicinity of at least one opening end, and the projections are grooves of the lateral grooves. The length in the groove direction at the bottom is 0.3 times or less and 4 mm or more of the groove length of the lateral groove, the width dimension is 0.6 times or less and 2 mm or more of the groove width of the lateral groove, and the height is the groove depth of the lateral groove. A pneumatic tire characterized in that the length in the direction of the groove at the top of the projection is at least 2 mm, which is 0.4 times or less and 2 mm or more.