JPH0648119A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To maintain a travel performance and reduce travel noise on an ice and snow covered road, and reduce a travel noise by forming a noise reduction projection having the predetermined values of length along a groove at the bottom thereof, width, height and length along a top groove in the vicinity of one opening end of a lateral groove. CONSTITUTION:A central longitudinal groove 3A extending in a tire peripheral direction and another longitudinal groove 3B between the groove 3A and a tread end E are formed on a tread section 2. In addition, lateral grooves 5 and 6 open to the grooves 3A and 3B, and both of the groove 3B and the tread end E are formed. Also, a projected section 9 is provided on a groove bottom in the vicinity of the open end F the lateral groove 5 to longitudinal grooves 3A and 3B, and the open end F of the lateral groove 6 to the longitudinal groove 3B. The length L of the section 9 along the direction of a groove at the bottom thereof is kept equal to or less than 0.3 times of groove length GL, and 4mm. The breadth W is kept equal to or less than 0.6 times of the breadth GW of the lateral grooves 5 and 5, and 2mm. Also, the height H from the groove bottom is kept equal to or less than the depth GH of the lateral grooves 5 and 6, and equal to or above 2mm, while the length of a crown section along a groove direction is made at least 2mm. As a result, a noise can be reduced, while road holding capability and travel capability on an ice and snow covered road being maintained.

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 achieving low noise while maintaining grip performance, particularly running performance on ice and snow.

[0002]

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

When traveling on ice, snow or soft roads,
While the block enhances grip, the groove efficiently discharges water adhering to the tread surface, closes the contact between the tread surface and the road surface, and increases the frictional resistance between the two surfaces, resulting in 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, air column resonance caused by abrupt discharge of compressed air through the columnar groove each time the tread surface comes into contact with the ground during traveling. Tire noise such as noise and noise caused by vibration of the block is generated. As the performance and sophistication of vehicles have increased, it has become more and more demanding to suppress tire noise in addition to improving grip performance for tires.

To reduce the noise, it is conceivable to make the groove, especially the lateral groove, shallow, but the shallower groove increases the rigidity of the block and reduces the grip performance on the icy and snowy road.

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

For example, Japanese Patent Laid-Open No. 2-14905 discloses an object to solve the above-mentioned problems by using an inclined groove which is inclined at a relatively small angle and is in contact with the ground contact surface. However, if the inclination angle of the lateral groove is small, the rigidity of the tread is reduced, which leads to a reduction in steering stability performance, and the groove in contact with the ground contact surface tends to cause insufficient traction performance on a wet road surface. Has not been completely resolved.

As a result of repeated studies to solve the above-mentioned problems, the inventor provided a protrusion at the opening end of the lateral groove to block a part of the air column resonance sound flowing through the lateral groove, thereby lowering the grip performance. The inventors have completed the present invention by discovering that noise can be reduced without causing it.

An object of the present invention is to provide a pneumatic tire capable of reducing the running noise of a tire while maintaining grip performance, particularly running performance on a snowy road, and which can be suitably adopted as a snow tire or a tire for running on rough terrain. There is.

[0010]

DISCLOSURE OF THE INVENTION The present invention is directed to a plurality of vertical grooves extending in the tire circumferential direction on a tread portion, and a lateral groove and a vertical groove extending in a direction intersecting with the vertical grooves and having both ends open as vertical grooves. And a tread edge, the pneumatic tire having a block pattern provided with outer lateral grooves having openings at both ends, wherein each lateral groove and at least one opening end is provided with a protruding portion for noise reduction protruding from a groove bottom. At the same time, the protrusion has a groove direction length at the groove bottom of the lateral groove equal to 0.3 of the groove length of the lateral groove.
2 times or less and 4 mm or more, the width dimension is 0.6 times or less and 2 mm or more of the groove width of the lateral groove, the height is 0.4 times or less and 2 mm or more of the groove depth of the lateral groove, and moreover, in the groove direction of the top of the protrusion. A pneumatic tire having a length of at least 2 mm.

[0011]

Function: A block pattern having vertical grooves and horizontal grooves is formed on the tread portion. The grip is maintained by this block when traveling on a snowy road. Also, since both ends of the lateral groove are open at the vertical groove or tread edge, water adhering to the ground contact surface can be efficiently drained by the lateral groove, and the contact between the tread surface and the road surface is made close to increase rolling friction resistance. The grip performance in rainy weather, that is, the wet grip performance can be improved.

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

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 of the groove depth.
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 deteriorated, which is not preferable.

On the contrary, when the length in the groove direction is less than 4 mm, the width dimension and the height are less than 2 mm, and the length in the groove direction at the top of the protrusion is less than 2 mm, the air passing through the lateral groove can be controlled. Since it is inferior, the air column noise generated from the lateral groove is not significantly reduced, and the noise suppression is insufficient.

[0015]

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

In this embodiment, the vertical groove 3 is a central vertical groove 3A located on the tire equator, and a pair of vertical vertical grooves 3A arranged between the central vertical groove 3A and the tread edge E. 3B, 3B
Further, the lateral groove 4 has an inner lateral groove 5 and a lateral longitudinal groove 3 whose both ends are opened by a central longitudinal groove 3A and a lateral longitudinal groove 3B, respectively.
B and the outer lateral groove 6 opening at the tread edge E are provided, and therefore the tread portion 2 has these vertical grooves 3 ...
A block pattern made up of blocks B surrounded by ... is formed.

In this embodiment, as shown in FIG. 1, a central vertical groove 3A, a lateral narrow groove 11A connecting the side vertical grooves 3B, and a vertical link connecting the lateral narrow grooves 11A in the circumferential direction. Narrow groove 11
B is established. Further, in this example, the vertical grooves 3 ... Are straight grooves, and the respective lateral grooves 5, 6 are formed as curved grooves which are inclined with respect to the tire axis.

Further, the pneumatic tire 1 has sidewall portions 13 and 13 extending inward in the tire radial direction from the tread portion 2 and bead portions 15 and 15 located at inner ends of the sidewall portion 13 in the radial direction. Have, each bead part 1
A toroidal carcass 17 passing through the sidewall portions 13 and 13 and the tread portion 2 is bridged between the bead cores 16 and 16 provided on the tires 5 and 15, and a belt layer 19 is provided radially outside and inside the tread portion 2. It is arranged.

The carcass 17 is a so-called radial or semi-radial direction 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, and as the carcass cord, nylon or polyester is used. , Organic fiber cords such as rayon and aromatic polyamide are adopted.

In this embodiment, two belt plies are arranged on the belt layer 19 from the carcass 17 side toward the outer side in the radial direction of the tire. Further, the belt layer 19 is provided with belt cords which are inclinedly arranged on the respective belt plies and intersect with each other. The belt cords are the same as the carcass 17, and 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 the straight groove as in this embodiment.

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

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

In these projections 9, the length L in the groove direction at the groove bottom 7 of the lateral grooves 5, 6 in which the projections 9 are located is 0.3 times or less the groove length GL of the lateral grooves 5, 6. 4 mm, and the width W is less than 0.6 times 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 0.4 times or less the groove depth GH of the lateral grooves 5 and 6 and 2 mm or more. Further, the protrusion 9 holds a length L1 in the groove direction at the top 10 thereof at least 2 mm.

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

[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. A conventional tire (Comparative Example 1) having no protrusion and a tire other than the configuration of the present application (Comparative Examples 2 to 2)
A test was also conducted for 4) to compare the performance.

The test conditions are as follows. B) Noise test Each test tire is a small 4-wheel drive vehicle (displacement 1600c
The sound pressure level of the noise was measured on the road noise measurement road while mounted on c) and running on a specific road noise test road, and displayed as an index with Comparative Example 1 being 100. The larger the number, the lower the noise.

(B) Snow test The same vehicle as in the item a) was mounted, and sudden braking was applied on ice with an outside air temperature of -5 ° C., the braking distance was measured, and the performance of Comparative Example 1 was set to 100 as an index. displayed. The larger the value, the better. The test results are shown in Table 1.

[0029]

[Table 1]

[0030]

As described above, in the pneumatic radial tire of the present invention, both ends are provided with vertical grooves or lateral grooves open at the vertical groove and the tread edge, and the groove bottom is provided in the vicinity of at least one opening end of the lateral grooves. Since the protrusions that are raised from the ground and regulate the length, width, and height in the groove direction are provided, the grip performance, especially the running performance on ice or snow can be maintained, while reducing the noise generated during running Alternatively, it can be suitably used as a tire for running on rough terrain.

[Brief description of 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 the line AA.

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

[Explanation of symbols] 2 tread portion 3 vertical groove 4 horizontal groove 5 horizontal groove 6 outer horizontal groove 7 groove bottom 9 protrusion 10 top E tread edge F opening end GH horizontal groove depth GL horizontal groove length GW horizontal groove Groove width H Height L Length L1 Top length W Width

Claims (1)

[Claims] 1. A plurality of vertical grooves extending in a tire circumferential direction on a tread portion, and lateral grooves extending in a direction intersecting with the vertical grooves and having both ends opened by vertical grooves, and both ends opened by a tread edge. A pneumatic tire having a block pattern provided with outer lateral grooves, which are provided with noise-reducing projections protruding from the groove bottom in the vicinity of each of the lateral grooves and 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 by being 0.4 times or less and 2 mm or more, and the length of the top of the protrusion in the groove direction is at least 2 mm.