JP2001063314A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce vibration of air in a groove, and reduce air pumping noise by arranging slits whose bottom part is the same depth as a groove bottom or shallower than it, on a groove wall of a rib, and set each slit depth and each slit thickness to specified sizes respectively, and setting each slit angle of an acute-angled side to an acute-angled side groove wall angle and less. SOLUTION: This tire is provided with at least one or more slits 4 in the tire circumferential direction on a groove wall 3 of one or more ribs 1 in a plurality of ribs for composing a tread. Each slit depth S of a length where the slits 4 are projected on a vertical line on a tread surface 2 is preferably within D/3<=S<D. A distance between the tread surface and a groove bottom is identified as D. Each slit thickness T is preferably within 0.4 mm<=T<=1.5 mm in a thickness of a direction perpendicular to the slit direction. Each slit angle is set to a groove wall angle and less, it is preferably about 5 degrees and less. Accordingly, a reducing effect of air pumping noise is exhibited regardless of a tire size.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire with reduced air pumping noise.

[0002]

2. Description of the Related Art In recent years, the deterioration of the environment of the earth has become a problem, and there are many problems required for automobiles. Under such circumstances, one of the problems that has been attracting attention is a noise problem, and further noise countermeasures have been required for tires, which are members that constitute a vehicle, together with noise generated from the vehicle body.

[0003] Tire noise (tire noise) is a phenomenon in which a tire directly or indirectly acts on a road surface to generate noise. Among them, pattern noise represented by air pumping noise or the like caused by a tread pattern is included. Is a sound that is generated between the tire contact surface and the road surface when the tire rolls, and such sound is unavoidable due to the structure of the tire, but due to the growing public interest in noise, etc. Low noise was desired.

[0004]

As described above, one of the sounds generated by the tread pattern is an air pumping sound. This is generated when the air in the tread groove in the tire contact surface is subjected to the pumping action of compression and release during traveling. One of the factors that increases the air pumping noise is that the air when the tire is in contact with the ground is contacted. The rib vibrates due to the impact, and this vibration causes the air in the groove to vibrate.

An object of the present invention is to reduce the air pumping noise by attenuating the vibration of the air in the groove caused by the vibration of the rib that increases the air pumping noise.

[0006]

As a result of intensive studies to solve the above problems, a notch is provided in the groove wall of the rib and the depth, thickness, angle and the like of the notch are optimized. Even when the ribs vibrate due to the impact when the tire touches the ground, the transmission of the vibrations is suppressed, and therefore, the vibration of the air in the grooves is attenuated, and the air pumping noise is reduced. .

That is, in order to achieve the above object, the present invention provides a pneumatic tire pattern having ribs connected in the tire circumferential direction, wherein at least one rib has groove walls.
The notch bottom is provided with a notch having the same depth as the groove bottom or shallower than the groove bottom, and a length formed by projecting on a line perpendicular to the tread surface of the notch is S (hereinafter, referred to as a notch depth), When the distance from the tread surface to the groove bottom is D, at least one notch is D / 3 ≦ S <D, and the notch thickness T (mm) is 0.4 ≦ T ≦ 1.5, In addition, of the two angles formed by the line perpendicular to the tread surface and the cut, the acute angle (hereinafter referred to as the cut angle) α is defined by the line perpendicular to the tread surface and the groove wall surface.
Provided is a pneumatic tire characterized in that the angle is less than an acute angle side (hereinafter, referred to as a groove wall angle) β among the three angles.

In the present invention, the cutting angle α is 5 °.
The following pneumatic tire is provided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional perspective view showing an example of a rib portion of the pneumatic tire of the present invention. The pneumatic tire according to the present invention has a rib 1 as shown in FIG. 1 in at least one of a plurality of ribs constituting a tread.
At least one notch 4 is provided in the groove wall 3 in the tire circumferential direction. The cuts 4 may be provided on one groove wall 3 of the rib 1 or on both groove walls 3 of the rib 1.

FIG. 2 shows a partial cross section of the rib 1 perpendicular to the tire circumferential direction and the tread surface. The notch 4 of the present invention refers to a position where the center line L of the notch 4 intersects with the groove wall 3 as a notch position P on the groove wall and from the notch position P to the bottom of the notch. The depth S of the cut is the length of the cut 4 projected onto a line perpendicular to the tread surface 2. Here, the depth S of the cut is preferably in the range of D / 3 ≦ S <D. However, the cut 4 must have a bottom portion extending parallel to the tread surface 2 to a line extending from the groove bottom 5 position or shallower than that. The reason why the depth of cut S is set to D / 3 or more is that if it is shallower, the effect of reducing the air pumping sound cannot be expected. The reason why the cut depth S is set to be equal to the depth of the groove bottom 5 is that if it is deeper than that, cracks are easily generated at the cut bottom and tire failure is caused.

The thickness T of the cut in the present invention refers to the thickness in the direction perpendicular to the cut direction, and 0.4 mm ≦ T ≦
A range of 1.5 mm is preferred, more preferably 0.4 m
m ≦ T ≦ 1.0 mm. When the thickness T of the cut is less than 0.4 mm, the stainless steel thin plate of the die forming the cut 4 is too thin, so that the strength is weak and breakage failure occurs easily, which makes production difficult. Also, when the thickness T of the cut exceeds 1.5 mm, the vibration of the rib 1 is easily transmitted to the air in the groove, and the damping effect is weakened.

The cutting angle α (the cutting angle α and the groove wall angle β described later in FIG. 3) of the present invention is smaller than the groove wall angle β, but is more preferably 5 ° or less. The reason for this is that when the cutting angle α increases, the function of suppressing the transmission of vibration generated in the rib 1 becomes weaker.

The cross-sectional shape of the cut 4 in the tire circumferential direction (cross-sectional shape as viewed from the Z direction in FIG. 1), the cross-sectional shape in the cut direction (cross-sectional shape as viewed from the X direction in FIG. 1), and the cut bottom in the tire circumferential direction are formed. The shape (the shape formed by the bottom as viewed from the Y direction in FIG. 1) is not particularly limited, and an appropriate shape such as a linear shape, a zigzag shape, or a wavy shape may be used. In the case of a non-linear shape such as the zigzag shape or the wavy shape, the size of the shape is not particularly limited as long as it does not hinder production. The shape of the groove-side portion where the cut 4 intersects with the groove wall surface is not particularly limited. For example, the groove-side portion 6 where the cut 4 intersects with the groove wall surface as shown in FIG. A surface may be provided. When various shapes such as the flat surface are provided, a position where this position intersects with the center line L of the cut is set as a cut position P, and a position from the cut position P to the cut bottom is set as a cut 4.

The effect of reducing the air pumping noise by providing the notch 4 in the groove wall 3 of the rib 1 as described above is exerted irrespective of the tire size, but is particularly remarkable in a heavy load tire.

As a method of forming the notch 4 of the present invention, a stainless steel thin plate may be provided so that the notch 4 is formed on the rib groove wall of the tire vulcanizing mold. A cut 4 is formed in 3.

[0017]

EXAMPLES The present invention will be described below in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

The tire size is 11R22.5 14P
R, a four-groove rib pattern was used, and cuts were provided in both groove walls of one rib located at the center in the width direction of the tread. The groove wall angle β is 12 °, and the distance D from the tread surface to the groove bottom is D.
Is 14.0 mm.

As described in Table 1, the depth of the cut S, the thickness T of the cut, the number of cuts, and the cut angle α are made different from those of the conventional example and Comparative Examples 1 and 2, and Example 1 as shown in Table 1.
Nine types of tires Nos. To 6 were manufactured.

With respect to the above nine types of tires, the unit noise was measured by the following measuring method, and the results shown in Table 1 were obtained.

Measurement method of unit noise : This measurement was performed by JAS
O. According to the measuring method based on C-606-81, the speed 4
It was performed at 0 km / h. Other conditions at the time of measurement are as follows. Air pressure: 700 kPa, load: 26.
72kN, rim: 22.5 × 8.25 (1999 J
ATMA YEAR BOOK 3-07 C02-2
Conditions).

The unit noise is represented by an index with the conventional example being 100, and the smaller the index is, the smaller the sound is and the more effective it is.

[0023]

[Table 1]

As is clear from Table 1, in Comparative Example 1 in which the depths S of the two cuts are as shallow as 0.2 D and 0.3 D, respectively, and in Comparative Example 2 in which the cut angle α is as large as 12 °, the conventional tire ( There is no improvement in single unit noise as compared to (no cut). On the other hand, it can be seen that the tires of Examples 1 to 6 have improved unit noise compared to the conventional tire.

[0025]

As described above, the present invention suppresses the vibration of the air in the groove caused by the vibration of the rib which increases the air pumping noise by providing the notch in the rib groove wall of the tire tread as described above. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional perspective view of a tread rib portion provided with a cut of the present invention in a groove wall.

FIG. 2 is a partial cross-sectional view of a plane perpendicular to a tire circumferential direction of a rib portion of the present invention.

FIG. 3 is an explanatory view showing a cutting angle and a groove wall angle of the present invention.

FIG. 4 is a partial cross-sectional view showing an example of the shape of a groove side portion where a cut and a groove wall surface intersect according to the present invention.

[Description of Signs] 1 rib 2 tread surface 3 groove wall 4 cut 5 groove bottom 6 groove side where cut and groove wall intersect D distance from tread surface to groove bottom L cut center line P cut position S cut Depth T Thickness of cut α Cut angle β Groove wall angle

Claims (2)

[Claims] 1. A pneumatic tire pattern having ribs connected in the circumferential direction of the tire, wherein at least one rib has a groove wall with a notch bottom having the same depth as the groove bottom or a notch smaller than the groove bottom. When the length formed by projecting the cut on a line perpendicular to the tread surface is S, and the distance from the tread surface to the groove bottom is D, at least one cut is D / 3 ≦ S <D. The thickness T (mm) of the cut is 0.4 ≦ T ≦ 1.5, and the acute angle α between the line perpendicular to the tread surface and the cut is defined by the line perpendicular to the tread surface and the groove wall surface. A pneumatic tire, wherein the angle is less than the acute angle side β. 2. The pneumatic tire according to claim 1, wherein an acute angle α formed by a line perpendicular to the tread surface and the cut is 5 ° or less.