JPH05310012A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve a coefficient of wet friction by forming an axial sipe on the preceding part of a block, connecting the succeeding part to the preceding part through a thin groove extending axially and forming a rounded part in the intersection of a side facing the thin groove and radial outside face. CONSTITUTION:A preceding part 3 previously contacting the ground in the rotation of a tire in the direction of arrow is formed with a plurality of axial sipes 6, and a succeeding part 4 is connected to the preceding part 3 through a thin groove 7 to form a block. The succeeding part 4 is formed on the preceding part 3 side, i.e., the front end edge with a rounded part 8. The blocks similarly constituted are formed circumferentially outside these blocks 5 through a circumferential groove.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a block formed with a thin notch for the purpose of improving the coefficient of wet friction μ.

[0002]

2. Description of the Related Art Conventionally, in a pneumatic tire in which a block pattern is formed on a tread surface of a tire, the block pattern having a large number of blocks defined by a circumferential groove of the tire and a lateral groove across the tire, There is a tire in which a plurality of thin notches, that is, sipes are provided in a direction intersecting the circumferential direction of a tire to improve the ground contact performance of the block, and the braking performance is imparted by the edge effect of the tip end of the sipes. As such a kind, one that attempts to improve braking performance on a snowy road or the like while maintaining the driving performance of a pneumatic tire by defining a sipe interval in order to improve braking performance on a low-friction road (for example, Japanese Patent Application Laid-Open No. Hei 10 (1999) Two
No. 169307).

[0003]

Although the sipe is generally cut in the land portion of the tread as described above, if there is a sipe in such a portion, braking / rotation during tire rotation may occur.
As a result of the driving force being applied, the tread floats up on the side that escapes from the contact surface with respect to the rotation direction, and the contact area, which is an important factor for ensuring the frictional force of the tire, decreases. Then, the coefficient of friction μ when wet was lowered, and the condition was not good.

The present invention was devised in order to solve the above-mentioned points, and the side surface and the diameter of the side of the tire block facing the narrow groove of the succeeding portion connected to the leading portion of the sipe in the block of the tire through the narrow groove. By rounding the part where the outer surface in the direction intersects, the tread is prevented from rising on the side that escapes from the contact surface with respect to the rotating direction of the subsequent part during tire rotation, and the reduction of the contact area is eliminated to reduce the wet friction coefficient. The purpose is to improve.

[0005]

To achieve the above object, the pneumatic tire of the present invention is divided into a plurality of circumferential grooves, a plurality of lateral grooves intersecting with the circumferential grooves, and the groove group. A separate block, the block having at least one leading axially extending sipe in the leading portion and a trailing portion subsequently grounding during travel. A trailing portion of the block is connected to the leading portion through an axially extending narrow groove, and a rounded portion is provided at a portion where a side surface facing the narrow groove and a radially outer surface intersect. It

[0006]

In the pneumatic tire configured as described above, the trailing portion and the leading portion of the block are connected to each other through the narrow groove extending in the axial direction, and the side surface of the trailing portion facing the narrow groove is formed. Since the portion where the radially outer surface intersects is rounded, the contact pressure distribution on the tread surface tends to be uniform during tire rotation, and as a result, the side that escapes from the contact surface with respect to the rotation direction of the subsequent portion of the block. There is little uplift and the reduction of the ground contact area can be prevented. Therefore, there is no decrease in the friction coefficient μ when wet.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a view showing a tread pattern of an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA in FIG. 3 and 4 are diagrams showing another embodiment of the present invention. FIG. 5: is explanatory drawing of the operating state of the block of the Example of this invention. FIG. 6 is a sectional view of a conventional example.

In FIG. 1, a tread pattern T of a pneumatic tire according to an embodiment of the present invention has a rib 1 with an equatorial plane C sandwiched therebetween.
Symmetrically extend in the circumferential direction, and circumferential grooves 2 are formed on both sides of the rib 1. On the outer side thereof, a block 5 which forms a block by a front portion 3 which the tire rotates in the direction of the arrow and which comes into contact with the ground and a rear portion 4 which interposes a narrow groove 7 is similarly continuously arranged in the circumferential direction. A plurality of sipes 6 (three in FIG. 1) are laterally cut in the leading portion 3. A rounded portion 8 is formed on the front end edge portion of the succeeding portion 4 which follows the leading portion 3 through a narrow groove 7 whose width is equal to or slightly wider than the width of the sipe. Blocks 5 ′ are provided in the circumferential direction on the outer sides of the blocks 5 which are continuously arranged in the circumferential direction, via a circumferential groove 2 ′, like the blocks 5. The block 5 ', like the block 5, comprises a leading portion 3'and a trailing portion 4',
Sipe 6'is cut in the leading portion 3'inclining upward from the end of the plurality of circumferential grooves 2'to the tread end 9. Subsequent part 4 via narrow groove 7'following preceding part 3 '
A slanted rounded portion is formed at the front edge portion of ′.

Reference numeral 10 is a lug groove. Here, the operating state of the pneumatic tire having such a tread pattern T on the wet road will be described with reference to FIG.
Now, as shown in FIG. 5, when the block slides on the water film of the wet, the ground contact pressure at the block edge and the sipe edge is increased and the drainage is good, while the ground contact pressure at the part of is decreased by rounding the edge of the subsequent part. Shows a tendency to be uniformed without causing a decrease in the contact area, and as a result, there is almost no decrease in the friction coefficient μ. In the above-mentioned embodiment, the block 5 is composed of one block of the leading portion 3 and the trailing portion 4, but FIG. 3 shows that the trailing portion is provided behind the trailing portion 4 through a narrow groove, and the leading edge thereof is provided. This is a structure in which a rounded portion is provided in the portion.

The embodiment shown in FIGS. 2 and 3 is an embodiment in which the rotation direction is specified. As a case where the rotation direction is not specified, the one shown in FIG. 4 is one block shown in FIG. A leading portion 3 and a succeeding portion 4 which follows through the narrow groove.
The structure corresponding to the preceding portion 3 in which the sipe 6 is further cut through the narrow groove is arranged at the back of the. FIG. 6 shows a conventional example in which a block is simply provided with a sipe.

2 and 4 and FIG. 6 having the tread pattern T shown in FIG. A sipe having a depth d = 7 mm and a pitch P = 3 mm between sipes was formed and applied to a tire having a tire size of 185 / 6bR14, and a test tire was prototyped and mounted on a passenger car and run on a wet road surface. . The results are shown below in terms of the performance during driving and braking, expressed as an evaluation index with the index of the conventional example as 100.

[0012]

[0013]

As described in detail above, the pneumatic tire of the present invention is constructed and has a block composed of a leading portion which comes into contact with the ground first while the tire is running and a trailing portion which comes into contact with the ground. At least one substantially axially extending sipe, and the trailing portion is connected to the leading portion through an axially extending narrow groove, and a rounded portion is formed at a portion where the side surface facing the narrow groove and the radially outer surface intersect. Is equipped with
Prevents the tread from rising on the side that escapes from the contact surface with respect to the rotation direction of the subsequent portion during tire rotation,
The reduction of the ground contact area can be suppressed, and as a result, the friction coefficient μ is hardly reduced, and the braking / driving performance of the tire on the wet road surface can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a tread pattern according to an embodiment of the present invention.

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

FIG. 3 is a sectional view of a block showing another embodiment of the present invention.

FIG. 4 is a sectional view of a block showing still another embodiment of the present invention.

FIG. 5 is a diagram showing an operating state during rotation of the block of the pneumatic tire of the present invention.

FIG. 6 is a sectional view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rib 2 circumferential groove 2'circumferential groove 3 leading portion 3'leading portion 4 trailing portion 4 'trailing portion 5 block 5'block 6 sipes 6'sipe 7 narrow groove 7' narrow groove 8 rounded portion 9 Tread edge 10 lug groove T tread pattern

Claims (1)

[Claims] 1. A plurality of circumferential grooves, a plurality of lateral grooves intersecting with the circumferential grooves, and an independent block sectioned by the groove group, wherein the block is followed by a preceding portion which is grounded first during traveling. In a tire having a trailing portion that comes into contact with the ground, the block includes at least one substantially axially extending sipe in the leading portion, and the trailing portion of the block is continuous with the leading portion through an axially extending slot. A pneumatic tire having roundness in a portion where a side surface facing the narrow groove and an outer surface in a radial direction intersect each other.