JPH04230407A - Pneumatic tire reducing noise - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire in which the tire noise caused by the sipes is advantageously reduced, particularly in tires with sipes formed in the tread.

0002

[Prior Art] A sipe is a tread with a cut of a certain depth over a predetermined length, and when the tire rolls, the side walls of the tread separate and open at the stepping-in and kick-off sides of the tread. However, it has a structure in which both side walls are closed together within the tread surface, which mainly contributes to lowering the compressive elastic constant of the tread land area. These sipes are normally arranged at approximately equal intervals in the circumferential direction of the tread, on land defined by a plurality of circumferential grooves extending along the circumference of the tread and at the edges of the tread. The sipe hits the ball regularly, so the sipe opens on the stepping side, contacts the ground, closes, and then opens again on the kicking side, which is repeated regularly.

0003

[Problem to be solved by the invention] On the other hand, the depth of the sipe and the shape of its bottom surface are uniform, and when the sipe opens and closes regularly as described above, the so-called pumping noise and collision sound also become regular. This results in monotonous noise,
Particularly on smooth paved roads, the noise is extremely high-pitched and harsh. Therefore, an object of the present invention is to propose a tread structure that can advantageously reduce tire noise caused by sipes.

0004

[Means for Solving the Problems] The inventors found that it is effective to change the opening/closing operation of the sipe, especially the opening shape, in order to reduce the tire noise described above, and in order to complete this invention. It has arrived. In other words, the present invention provides a tread that extends in a toroidal manner between a pair of sidewalls, and a plurality of circumferential grooves that extend along the circumference of the tread that are parallel to each other at intervals in the axial direction of the tire, and a tread edge. A pneumatic tire is provided with a land section divided by a tread, and sipes extending in a direction intersecting the circumferential groove are arranged in the land section at intervals in the tread circumferential direction, the arrangement of the sipes being orthogonal projection. This is a pneumatic tire with reduced noise, which is a combination of sipes with different bottom shapes and/or areas.

Now, FIG. 1 shows a main part of the tread of a pneumatic tire according to the present invention. , 1b and a central circumferential groove 2 extending on the central circumferential line O, and lateral grooves 3a, 3b and 4a, 4b extending across these circumferential grooves and connecting each circumferential groove or between the circumferential grooves 1a, 1b and the tread end T. According to the center circumferential line O
Two columns on one side and four columns of vertical block groups 5 to 8 on both sides are partitioned. Further, each block of the column block groups 5 and 6 is provided with a sipe 9 that divides the block almost equally in the circumferential direction and extends parallel to the transverse grooves 3a and 3b in this embodiment. This sipe 9 has auxiliary lateral grooves 10a and 10
b to the circumferential grooves 1a and 1b and the central circumferential groove 2, and further connects these auxiliary lateral grooves 10a and 10b and these auxiliary lateral grooves and lateral grooves 3a and 3b through a route different from the sipe 9, and A sipe 11 is provided which joins the sipe 9 at the lateral grooves 10a and 10b. Furthermore, each block of the column block groups 7 and 8 is provided with a sipe 12 that divides the block almost equally in the circumferential direction, and this sipe 12 has circumferential grooves 1a, 1b and auxiliary lateral grooves extending from the tread end T toward the shoulder portion. 13.

[0006] Here, in each block, it is important to combine in the circumferential direction multiple types of sipes that differ in at least one of the bottom shape and area (hereinafter referred to as orthogonal projection shape and orthogonal projection area) in orthogonal projection. be. That is, in the tread pattern shown in FIG. 1, the tread patterns shown in FIGS.
Sipes having different orthogonal projection shapes shown in FIG. 1 are arranged in combinations B to G in FIG. 1 to realize a sipe arrangement in which the opening and closing operations of the sipes have no regularity in the tread circumferential direction.

FIG. 3 also shows a tread pattern in which ribs 14 to 17 are defined between the circumferential grooves 1a, 1b and the central circumferential groove 2 and the tread end T.
A sipe 18 is provided that divides each of the sipes approximately equally in the tread circumferential direction, and the sipes of different orthographic shapes shown as U to Z in FIGS. 4(A) to 4(C) correspond to U to Z shown in FIG. 3. This is an example of a combination and arrangement. By the way, Sipe 18 extends in a step-like manner, so Figure 4 shows Sipe 1.
The orthogonal projections of each straight line part of 8 are combined and shown.

[0008] Other structures of the tire according to the present invention include:
It may be in accordance with conventional tire practices. In other words, the carcass consists of at least one turn-up ply (three at most) wrapped around a bead core from the inside of the tire to the outside, and the ply consists of fiber cords, typically rayon, nylon, and polyester, wrapped around the tire's equator. The belt layer consists of non-extensible cords such as steel cords and aromatic polyamide fiber cords arranged at an angle of 10 to 35 degrees to the equatorial plane of the tire. At least one auxiliary layer of heat-shrinkable cord, typically a nylon cord, arranged substantially parallel to the equatorial plane of the tire over the entire width of the main belt layer, consisting of at least two layers of belts arranged at an angle and arranged across each other. The belt layer is formed by spirally winding a ribbon in which a plurality of cords are arranged along the circumference of the main belt layer. Then, the above-described tread is placed on this belt layer.

[0009]

[Function] As shown in Figure 5, the sipe opens on the stepping side and the kicking side and closes within the tread surface, reducing pumping noise caused by air pumping within the sipe and collision with the road surface due to this opening and closing movement. As a result of the impact sound generated by the collision and the regular repetition of the opening and closing movement of the sipes due to the rotation of the tire, the above-mentioned sound also becomes a regular and monotonous noise. Therefore, in this invention, by arranging the sipes in a combination of sipes that differ in at least one of the orthogonal projection shape and the orthogonal projection area, we mainly avoid the opening shape of the sipes from becoming uniform and white To reduce noise and suppress regular and monotonous noise. That is, the opening shapes of the various sipes shown in FIGS. 2(A) to 2(G) on the stepping-in side and the kicking-out side are changed to the orthogonal projection shape as shown in FIGS. 6(A) to (G). This prevents the sound generated when the sipe is opened from becoming a single sound. Here, Table 1 shows the sound pressure level and its orthogonal projected area at which sipes having the opening shapes shown in FIGS. 6(A) to 6(G) occur. Note that this table is expressed as an index when the sound pressure level and the orthogonal projected area of the conventional sipe shown in FIG. 2(A) are taken as 100.

0010

[Table 1]

It can be seen from the table and FIGS. 2 and 6 that the sound pressure level can be changed by changing the orthogonal projection shape, that is, the aperture shape. Also shown in Figure 2, (A) and (F)
The sipes in (B) and (G) are examples of the same orthogonal projection shape but different orthogonal projection areas, and as shown in the table, it can be seen that the sound pressure level can be changed even if the orthogonal projection area is changed. Therefore, if at least two types of sipes with different orthogonal projection shapes and/or orthogonal projection areas are applied to the sipe rows in the circumferential direction of the tread, regular and monotonous noise can be changed into a rounded sound, so-called white noise. It can be achieved.

0012

[Example] In prototyping a pneumatic radial tire with a tire size of 185/70R14 according to the tread pattern shown in Fig. 3, orthographic projection shapes of types U to Z shown in Figs. 4(A) to (C) were prepared. sipes were applied in the combinations shown in Table 2. Each of the above tires was assembled on a 5J x 14 rim, an internal pressure of 2.2 kgf/cm2 was applied, and the tires were mounted on a front wheel drive vehicle to evaluate noise. The results are also listed in Table 2. Regarding noise, the sound inside the car was evaluated by feel while the car gradually decelerated from 80 km/h until it came to a stop on a smooth road surface, and the results were shown using a point deduction method with a maximum score of 10 points.

[0013]

[Table 2] Note) *1: For example, 2 of the same type of sipe as XXYYZZ
Repeated times *2 3 points: The noise caused by the sipes is clear and very harsh. 6 points: The noise caused by the sipes is significantly reduced, but the humming noise caused by the sipe arrangement is a little bothersome. 9 points. : There is no noise at all, and the sound can be heard if you pay attention.

[0014]

[Effects of the Invention] According to the present invention, it is possible to reduce the noise caused by the sipes by converting them into white noise in a tire in which sipes are applied at approximately equal intervals in the circumferential direction of the tread. It is possible to provide a tire with excellent noise characteristics.

[Brief explanation of the drawing]

FIG. 1 is a developed view of a main part of a tread of a pneumatic tire according to the present invention.

FIG. 2 is an orthogonal projection view of sipes.

FIG. 3 is a developed view of a main part of a tread showing another tire according to the present invention.

FIG. 4 is an orthogonal projection view of sipes.

FIG. 5 is a schematic diagram showing opening and closing of sipes during tire rolling.

FIG. 6 is a schematic diagram showing the shape of an opening of a sipe.

[Explanation of symbols]

1a Circumferential groove 1b Circumferential groove 2 Central circumferential groove 3a Horizontal groove 3b Horizontal groove 4a Horizontal groove 4b Horizontal groove 5 Column block group 6 Column block group 7 Column block group 8 Column block group 9 Sipe 10a Auxiliary horizontal groove 10b Auxiliary horizontal groove 11 Sipe 12 Sipe 13 Auxiliary horizontal groove 11...Auxiliary cut

Claims (1)

[Claims] Claim 1: A tread extending in a toroidal shape between a pair of sidewalls, a plurality of circumferential grooves extending along the circumference of the tread parallel to each other at intervals in the axial direction of the tire, and a tread edge. A pneumatic tire is provided with a land section divided by a tread, and sipes extending in a direction intersecting the circumferential groove are arranged in the land section at intervals in the tread circumferential direction, the arrangement of the sipes being orthogonal projection. A pneumatic tire with reduced noise, comprising a combination of sipes having different bottom shapes and/or areas.