JPH0195913A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To discharge air, enveloped in the bottom part of a calf, from tubular space so as to reduce a pattern noise by providing the calf in a block on a tread surface further forming the tubular space, whose diameter is larger than a width of the calf, in the bottom part of the calf. CONSTITUTION:A tire forms on its tread surface a tread pattern combining many blocks with grooves. Here each block 1 provides a notch of narrow width, that is, a calf 2 while forming its both opening ends in a shallow groove for obtaining the uniformity of rigidity. Tubular space 3, whose diameter (d) is larger than a width (w) of the calf 2, is formed from one end of the calf 2 toward the other end in the bottom part of each calf 2. By the structure thus obtained, discharging air, enveloped in the bottom part of the calf 2, from the tubular space 3 by the contact of the tread surface with a road surface during rolling of the tire thus releasing the air at a stroke when a tread performs the kick out action, a generated noise is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pneumatic tire with reduced pattern noise.

[Prior art]

Conventionally, a complex tread pattern is formed on the tread surface of a tire by combining a plurality of blocks and grooves.

The block is provided with a narrow cut called a kerf, mainly to increase braking force when driving on a wet road and to equalize block rigidity. In particular, in all-season tires or snow tires, each block is provided with a kerf to increase traction on icy and snowy roads. Figures 3(A) and 3(B) show an example of a conventional tire block with a kerf.

In these figures, 1 is a block.

In FIG. 3(A), the block 1 is provided with a linear kerf 2 with both ends open, and in FIG. 3(B), the block 1 is provided with a curved kerf 2 with one end open. ing. In order to prevent the rigidity of the free ends of these kerfs 2 from becoming low and prone to uneven wear, the bottoms of these kerfs 2 are made shallow (shallow grooves) as shown by a to make the rigidity uniform. However, due to this shallow groove, a deep part is formed in the kerf 2, so when the tread surface contacts the road surface during running, air is trapped in this deep part, and when the air is released, noise is generated. Occur. That is, pattern noise occurs due to air pumping, which is currently a major problem.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire that reduces pattern noise by preventing pattern noise from occurring due to air bombing.

[Structure of the invention]

Therefore, the present invention is characterized in that a kerf is provided in the block on the trend surface, and a cylindrical space whose diameter is larger than the width of the kerf is formed at the bottom of the kerf, extending from one end of the kerf to the other end. This article focuses on pneumatic tires.

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings.

FIG. 1(A) is a perspective explanatory view of an example of a block of a pneumatic tire according to the present invention, FIG. 1(B) is a longitudinal cross-sectional view thereof, and FIG. 1(C) is a cross-sectional view thereof.

In FIGS. 1(A), (B), and (C), a block 1 on the tread surface is provided with a kerf 2.
Both open ends are shallowly grooved as shown by a in order to make the rigidity uniform. A cylindrical space 3 having a diameter d larger than the width W of the calf 2 is formed at the bottom of the calf 2 from one end of the calf 2 to the other end.

The diameter d is preferably in the range of 1.2W≦d≦2W. Here, the maximum value of the diameter d is 2 of the width W of the kerf 2.
The reason why it is set to double that is because if it exceeds this, the block rigidity will drop significantly, and the resistance will increase when releasing from the mold during the vulcanization process during manufacturing, making it more likely to cause failures such as rubber breakage. . Further, the reason why the diameter d is set to be 1.2 times or more the width W of the kerf 2 is that if it is less than 1.2 times, the effect of reducing pattern noise cannot be seen.

The cross section of the cylindrical space 3 may be circular or polygonal, but from a practical point of view it is preferably circular.

FIG. 2 is a separate perspective explanatory view of the block of the pneumatic tire of the present invention. As shown in FIG. 2, the calf 2 may be open at only one end.

Examples are shown below.

Example Pattern noise was measured for the following tires of the present invention and conventional tires. The results are shown in Table 1 below as an index.

(1) Tire of the present invention.

Tire size P155/80 R13, tire pattern Y-382, having the block structure shown in FIGS. 1(A), (B), and (C), aw = 31111.
d −1,5Xvr=1.5 X 3 −4.5
-One.

(2) Conventional tires.

It has a tire size of P155/80 R13, a tire pattern of Y-382, and a block structure shown in FIG. 3(A). That is, it is the same as the tire of the present invention described above except that it does not have the cylindrical space 3.

Burn noise: When driving on a dry road at an initial speed of 120 km+/h, with the engine stopped and the clutch disengaged and no driving force transmitted, coasting until the vehicle speed reaches 20 km+/h. The sound generated from the tires was measured, and the average value was compiled for each speed range. The measurement was carried out three times, and the average value was expressed as an index for each speed range and is shown in Table 1 below. The smaller the value, the lower the noise.

Topsoil: 2 layers: 1 square meter of engineered soil 1 meter of engineered soil 80-100 cm/h 97 10060-801v
/h 98 10040~60
Sv/h 99
10020~40km/h
99 100 As is clear from Table 1, the tire of the present invention has reduced pattern noise compared to the conventional tire in the high speed range of 60 km/h or higher.

〔Effect of the invention〕

As explained above, according to the present invention, the air wrapped in the bottom of the kerf due to contact between the tread surface and the road surface is discharged from the cylindrical space during driving, so when the tread kicks off while driving, the air is released. It is possible to reduce the sound generated by sudden release. Therefore, according to the present invention, it is possible to prevent pattern noise from occurring due to air pumping and to reduce pattern noise. Further, according to the present invention, since a cylindrical space whose diameter is larger than the width of the carf is formed at the bottom of the carf from one end to the other end of the carf, the movement of the block becomes smooth, making it easier to drive on snowy roads. Performance (braking performance, traction) is improved and stress concentration on the kerf is alleviated, reducing the occurrence of cranks and improving drainage performance when driving on wet roads.

[Brief explanation of the drawing]

FIG. 1(A) is a perspective explanatory view of an example of a block of a pneumatic tire according to the present invention, FIG. 1(B) is a longitudinal cross-sectional view thereof, and FIG. 1(C) is a cross-sectional view thereof. FIG. 2 is a separate perspective explanatory view of the block of the pneumatic tire of the present invention. FIGS. 3A and 3B are perspective explanatory views of an example of a block of a conventional pneumatic tire. 1...Block, 2...Curf, 3...Cylindrical space. Agent Patent Attorney Nobuo Ogawa −

Claims (1)

[Claims] A kerf is provided in the block on the tread surface, and a cylindrical space having a diameter larger than the width of the kerf is formed at the bottom of the kerf from one end of the kerf to the other end. pneumatic tires.