JP2001191742A - Heavy load pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heavy load pneumatic tire having effectively reduced vibration noises at tire side portions in conjunction with the rolling of the tire without marring the lopsided wear resistance of the tire and limiting its shape. SOLUTION: The heavy load pneumatic tire comprises a tread portion 3 annularly formed, a pair of sidewall portions 4 arranged ranging from both ends of the tread portion 3 to the insides in a tire radial direction, and bead portions ranging to the insides of the sidewall portions 4 in the tire radial direction. A rubber 5 having a higher specific gravity than surrounding rubbers is used in a portion of a rubber on a carcass ply 1 in a section S ranging from the end of the tread portion 3 to the maximum tire width position of the sidewall portions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heavy-duty pneumatic tire applied to heavy-duty vehicles such as trucks and buses, and more particularly to a heavy-duty pneumatic tire capable of effectively reducing noise caused by rolling. .

[0002]

2. Description of the Related Art Noise caused by the rolling of a pneumatic tire is mainly caused by a tread pattern. To reduce such noise, the shape of the tread pattern is changed or the pitch variation is changed. Most were.

[0003] Recently, as the noise problem of traffic vehicles has become more serious, it has been strongly desired to reduce tire noise especially in heavy-duty vehicles such as trucks and buses. However, in the application of the noise reduction method as described above,
Since the effect of the improvement is small and a satisfactory result cannot be obtained, in addition to the improvement of the tire tread portion, the following methods for reducing noise due to the vibration of the tire side portion have been proposed.

[0004] By changing the pitch of the tread pattern, that is, by changing the pitch of the tread pattern to a so-called variable pitch, the pattern input frequency serving as a basis for transmitting the vibration of the side portion is dispersed.

[0005] By providing a side protector or the like at the tire side portion, the outer shape of the tire side is changed to increase the mass of the portion, thereby suppressing the vibration of the tire side portion.

[0006]

However, these methods have the following problems. That is, in the method (1), the size of the pattern becomes non-uniform on the circumference of the tire, so that there is a problem that the uneven wear resistance of the tire is reduced. Also,
According to the method (1), there is a limit to the shape of the tire in order not to impair various performances of the tire. Therefore, the noise reduction effect has a limit.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heavy-duty tire capable of effectively reducing the vibration noise of the tire side portion caused by the rolling of the tire without impairing the uneven wear resistance of the tire and without limiting the shape. It is to provide a pneumatic tire.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the inventor of the present invention has made intensive studies focusing on the side portion of the tire, and as a result, has found that the tire extends from the end of the tread portion to the tire maximum width position of the sidewall portion. The present inventors have found that the above object can be achieved by using a rubber having a higher specific gravity than a surrounding rubber as a part of the rubber on the carcass ply in the section, and completed the present invention.

That is, the pneumatic tire for heavy load according to the present invention includes a tread portion formed in an annular shape, a pair of sidewall portions disposed radially inward from both ends of the tread portion in the tire radial direction, and the sidewall portion. In a heavy-duty pneumatic tire having a bead portion that extends inward in the tire radial direction, a part of the rubber on the carcass ply in a section from the end of the tread portion to the tire maximum width position of the sidewall portion, It is characterized in that rubber having a higher specific gravity than the surrounding rubber is used.

In the present invention, the high specific gravity rubber (hereinafter referred to as "high specific gravity rubber") has a specific gravity of 1.3 or more, and the surrounding rubber (hereinafter referred to as "low specific gravity rubber").
Is preferably 1.2 or less, and the mass a of the high specific gravity rubber and the mass b of the low specific gravity rubber b in the above section.
The ratio [a / (a + b)] is preferably 0.01 or more. The location of the high specific gravity rubber may be anywhere from the tire surface layer, the tire inner layer on the carcass ply, or the tire inner layer on the carcass ply to the tire surface.

In the heavy duty pneumatic tire of the present invention, a part of the rubber on the carcass ply in a section from the end of the tread portion to the tire maximum width position on the sidewall portion has a specific gravity higher than that of the surrounding rubber. The use of the high rubber increases the mass of the portion, and as a result, the vibration of the tire side surface is reduced, and the noise radiated from the tire side surface is reduced. Since the high specific gravity rubber is included in the tire side portion, there is no accompanying change in side shape or pattern that impairs various performances as a tire.

[0012]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 shows a left-side main part of a heavy-duty pneumatic tire according to a preferred embodiment of the present invention. In the figure,
The carcass ply 1 straddles a pair of bead cores (not shown) in a toroidal shape, and a belt 2 having four layers is disposed radially outward, and a tread 3 is further radially outward. Are located. A pair of sidewalls 4 are disposed radially inward from both ends of the tread 3 in the tire radial direction.

In the present invention, a section S from the end E of the tread 3 to the tire maximum width position W of the sidewall 4 is set.
As a part of the rubber on the carcass ply 1, the high specific gravity rubber 5 having a higher specific gravity than the surrounding rubber is used. In the example shown in the figure, the high specific gravity rubber 5 is arranged on the inner layer of the tire on the carcass ply 1.

If the location of the high specific gravity rubber 5 is higher than the end E of the tread 3, or if the lower end is lower than the tire maximum width position W, the suppression of the side vibration is reduced, which is not preferable. The specific gravity of the high specific gravity rubber 5 is preferably 1.3 or more, and particularly preferably 1.5 to 2. Specific gravity is 2.
If it exceeds 5, the noise reduction effect is no longer improved, and the other performance of the tire is adversely affected. On the other hand, the specific gravity of the low specific gravity rubber around the high specific gravity rubber 5 in the section S is preferably 1.2 or less. If the specific gravity is larger than 1.2, the effect of suppressing tire side vibration cannot be sufficiently obtained.

In the present invention, the specific gravity of the high specific gravity rubber 5 and the surrounding low specific gravity rubber is adjusted by, for example, adding a metal or a metal oxide or adjusting the amount of the metal or metal oxide in a commonly used rubber composition. Although it is not particularly limited, it is preferably adjusted with zinc white from the viewpoint of the adhesion between the high specific gravity rubber 5 and the surrounding low specific gravity rubber.

The ratio [a / (a + b)] of the mass a of the high specific gravity rubber 5 and the mass b of the low specific gravity rubber in the section S is:
It is preferably 0.01 or more, more preferably 0.0
2 to 0.05. If this ratio is less than 0.01, the effect of suppressing tire side vibration cannot be sufficiently obtained.

FIG. 2 shows a left main part of a heavy-duty pneumatic tire according to another preferred embodiment of the present invention. The arrangement of the carcass ply 1, the belt 2, the tread 3, the sidewalls 4 and the like is not different from that of the preferred embodiment shown in FIG. 1, and only the arrangement of the high specific gravity rubber 5 is changed. It was present from the inner layer of the tire on the carcass ply 1 to the surface layer of the tire.

FIG. 3 shows a left main part of a heavy-duty pneumatic tire according to still another preferred embodiment of the present invention. This preferred example also differs from the preferred example shown in FIG. 1 only in the location of the high specific gravity rubber 5, and the high specific gravity rubber 5 is present on the tire surface layer. In any of these preferred embodiments, the high-specific-gravity rubber 5 is arranged in the area of the section S, as in the preferred embodiment shown in FIG.

In the heavy duty pneumatic tire according to the present invention, the improvement of the rubber in the section from the end of the tire tread portion to the tire maximum width position of the sidewall portion is used. Can be determined in accordance with

[0020]

The present invention will be described below in more detail with reference to examples and comparative examples. Example A heavy-duty pneumatic tire of size 11R22.5 having a side structure shown in FIG. 1 was prototyped. As the high specific gravity rubber 5 in the section S, the thickness is 5 mm, the width is 35 mm, and the specific gravity is 1.
5 rubbers were provided. The specific gravity of the low specific gravity rubber around the high specific gravity rubber 5 was set to 1.1. In addition, the ratio [a /
(A + b)] was set to 0.03.

COMPARATIVE EXAMPLE As a comparative example, in the tire of the example, the specific gravity of the portion where the high specific gravity rubber 5 was disposed was set to 1.1 and the same as the specific gravity of the surrounding low specific gravity rubber. A heavy-duty pneumatic tire was prototyped.

Each of the tires of the embodiment and the comparative example was mounted on a regular rim, and the air pressure was 700 kPa and the load was 24.5 kN.
A noise test was conducted. The noise test was performed as an indoor noise test (drum: speed of 50 km / h) by placing a microphone at a position 50 cm away from the tire and measuring the overall value. Noise measurement is an overall value (A)
Thus, the tire of the example is -1.8 d in comparison with the tire of the comparative example.
The effect of reducing B (A) was observed.

[0023]

As described above, in the pneumatic tire for heavy load according to the present invention, the tire which accompanies the rolling of the tire without impairing the uneven wear resistance of the tire and without being limited by the shape. Vibration noise of the side part can be effectively reduced.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a heavy-duty pneumatic tire according to a preferred embodiment of the present invention.

FIG. 2 is a partial sectional view of a heavy-duty pneumatic tire according to another preferred embodiment of the present invention.

FIG. 3 is a partial cross-sectional view of a heavy-duty pneumatic tire according to still another preferred embodiment of the present invention.

[Description of Signs] 1 Carcass ply 2 Belt 3 Tread section 4 Side wall section 5 High specific gravity rubber

Claims (6)

[Claims] An annular tread portion, a pair of sidewall portions disposed radially inward from both ends of the tread portion in the tire radial direction, and a bead portion connected to the sidewall radially inward in the tire radial direction. In a heavy-duty pneumatic tire comprising: a portion of the rubber on the carcass ply in a section from the end of the tread portion to the tire maximum width position of the sidewall portion, a rubber having a higher specific gravity than surrounding rubber. A pneumatic tire for heavy loads, characterized by using: 2. The heavy duty pneumatic tire according to claim 1, wherein the high specific gravity rubber has a specific gravity of 1.3 or more, and the peripheral rubber has a specific gravity of 1.2 or less. 3. The ratio [a / (a +) of the mass a of the high specific gravity rubber and the mass b of the surrounding rubber in the section.
3. The pneumatic tire for heavy load according to claim 1, wherein b)] is 0.01 or more. 4. The heavy-duty pneumatic tire according to claim 1, wherein the rubber having a high specific gravity is disposed on a surface layer of the tire. 5. The heavy-duty pneumatic tire according to claim 1, wherein the rubber having a high specific gravity is disposed in a tire inner layer on the carcass ply. 6. The heavy-duty pneumatic tire according to claim 1, wherein the rubber having a high specific gravity is disposed between the tire inner layer portion on the carcass ply and the tire surface layer portion.