pneumatic tires

Abstract

To provide a pneumatic tire capable of improving a noise performance by efficiently absorbing sound.SOLUTION: The present invention relates to a pneumatic tire 1 having a tread part 2. The pneumatic tire 1 is arranged with a sponge-like sound absorption body 5 in an inner surface side of the tread part 2. A ratio (H / T) of a hardness H (N) of the sound absorption body 5 at the time of 25% compression at 23°C and a height T (mm) of the sound absorption body 5 in a tire radial direction is 1.0 to 2.5. A ratio (T / W) of the height T (mm) of the sound absorption body 5 and a width W (mm) in a tire axial direction is 0.25 to 1.20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pneumatic tire having a tread portion. [Background technology]

[0002] Conventionally, pneumatic tires have been known in which a sponge-like sound-absorbing body is fixed to the inner side of the tread. For example, Patent Document 1 below proposes a pneumatic tire that can reduce road noise over a long period of time by specifying the height and shape of the sound-absorbing body and the hardness, tensile strength, and specific gravity of the sponge material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2006-306302 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in pneumatic tires with sound absorbing materials fixed to the inner surface of the tread, the sponge-like sound absorbing material is fixed to the inner surface, which increases costs, increases weight, and causes heat accumulation, which can result in a decrease in performance such as cost performance, steering stability, fuel efficiency, and durability. Therefore, a pneumatic tire that can absorb sound more efficiently has been desired.

[0005] The present invention has been devised in view of the above circumstances, and has as its main object to provide a pneumatic tire that can improve noise performance by efficiently absorbing sound. [Means for solving the problem]

[0006] The present invention is a pneumatic tire having a tread portion, in which a sponge-like sound absorbing material is arranged on the inner side of the tread portion, the ratio (H / T) of the hardness H (N) of the sound absorber at 25% compression at 23°C to the height T (mm) of the sound absorber in the radial direction of the tire is 1.0 to 2.5, and the ratio (T / W) of the height T (mm) of the sound absorber to the width W (mm) in the axial direction of the tire is 0.25 to 1.20. [Effects of the Invention]

[0007] By having the above-described configuration, the pneumatic tire of the present invention can efficiently absorb sound and improve noise performance. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing an embodiment of a pneumatic tire of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 1 is a tire meridian cross-sectional view including a rotation axis showing a pneumatic tire 1 of this embodiment in a normal state. Here, the "normal state" refers to a state in which the pneumatic tire 1 is mounted on a normal rim, adjusted to a normal internal pressure, and no load is applied. Unless otherwise specified below, the dimensions of each part of the pneumatic tire 1 are values ​​measured in this normal state.

[0010] If there is a standard system including the standard on which the pneumatic tire 1 is based, the "genuine rim" is the rim R determined for each tire by that standard, for example, "standard rim" for JATMA, "design rim" for TRA, and "measuring rim" for ETRTO. If there is no standard system including the standard on which the pneumatic tire 1 is based, the "genuine rim" is the rim R with the smallest rim diameter and the smallest rim width among rims R that can be assembled and do not cause air leakage.

[0011] "Normal internal pressure" is the air pressure set for each tire by a standard set by the JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for the TRA, and the "INFLATION PRESSURE" for the ETRTO. If there is no standard set that includes the standard set by the pneumatic tire 1, "normal internal pressure" is the air pressure set for each tire by the manufacturer, etc.

[0012] As shown in FIG. 1, the pneumatic tire 1 of this embodiment has a tread portion 2 extending in an annular shape, a pair of sidewall portions 3 on both sides of the tread portion 2 in the tire axial direction, and bead portions 4 on the radially inner side of each sidewall portion 3.

[0013] In this embodiment, the radially outer side of the tread portion 2 constitutes a contact patch 2s that comes into contact with the road surface during running. The sidewall portions 3 desirably extend radially inward from both axial sides of the tread portion 2. For example, a buttress portion is provided between the tread portion 2 and the sidewall portions 3. The bead portions 4 include, for example, a portion that comes into contact with the rim R when the tire is mounted on a rim.

[0014] The pneumatic tire 1 of this embodiment has a sponge-like sound absorbing body 5 disposed on the inner surface side of the tread portion 2. The sponge-like sound absorbing body 5 is preferably a porous material having a plurality of cells therein. Such a sound absorbing body 5 can absorb vibrations in a specific frequency range, thereby improving the noise performance of the pneumatic tire 1.

[0015] The ratio (H / T) of the hardness H (N) of the sound absorber 5 at 23°C when compressed by 25% to the height T (mm) of the sound absorber 5 in the tire radial direction is preferably 1.0 to 2.5. The ratio (T / W) of the height T (mm) of the sound absorber 5 to the width W (mm) in the tire axial direction is preferably 0.25 to 1.20. Here, the hardness H (N) at 23°C when compressed by 25% is a value measured in accordance with the provisions of JIS K6400-2.

[0016] Such a sound absorber 5 has a natural frequency close to the resonance frequency of the pneumatic tire 1, and can attenuate noise in the range of about 160 to 250 Hz by resonating with the pneumatic tire 1, thereby significantly improving sound absorption efficiency. Therefore, the pneumatic tire 1 of this embodiment can efficiently absorb sound and improve noise performance.

[0017] That is, in the pneumatic tire 1 of this embodiment, by limiting the dimensions and hardness of the sound absorber 5 to a specific ratio, the pneumatic tire 1 and the sound absorber 5 can resonate with each other without the need for a separate weight or the like. From this perspective, the ratio (H / T) of the hardness H (N) to the height T (mm) of the sound absorber 5 is more preferably 1.2 to 2.1. Furthermore, the ratio (T / W) of the height T (mm) to the width W (mm) of the sound absorber 5 is more preferably 0.65 to 1.13, and even more preferably 0.80 to 1.00.

[0018] In a more preferred embodiment, the sound absorber 5 is fixed to the inner surface of the tread portion 2 via double-sided tape, adhesive, pressure-sensitive adhesive, or sealant. Such a sound absorber 5 is easy to install and helps reduce manufacturing costs. Note that the sound absorber 5 may also be disposed, for example, without being fixed to the inner surface of the tread portion 2.

[0019] The cross-sectional shape of the sound absorber 5 of this embodiment in a tire meridian cross section is rectangular. Such a sound absorber 5 is likely to resonate with the pneumatic tire 1, improving sound absorbing performance. Furthermore, such a sound absorber 5 is easy to manufacture, which helps reduce manufacturing costs.

[0020] The sound absorber 5 of this embodiment is provided continuously in the tire circumferential direction. Such a sound absorber 5 can provide a uniform sound absorbing effect all around the circumference of the pneumatic tire 1. However, the sound absorber 5 is not limited to this form, and for example, it may have a discontinuous portion in the tire circumferential direction, or multiple sound absorbers 5 may be fixed.

[0021] The sound absorber 5 is made of, for example, urethane foam. The urethane foam may be made by a known manufacturing method. Such a sound absorber 5 can be selected from mass-produced products, which helps reduce manufacturing costs.

[0022] The height T of the sound absorber 5 is preferably 10 to 80 mm. When the height T of the sound absorber 5 is 10 mm or more, the sound absorber 5 can resonate with the pneumatic tire 1. When the height T of the sound absorber 5 is 80 mm or less, it is possible to suppress any effects on steering stability and the work of assembling the sound absorber to the rim R.

[0023] The number of cells in the sound absorber 5 is preferably 38 to 50 cells / 25 mm. Here, the number of cells is a value measured in accordance with Appendix 1 of JIS K6400-1. If the number of cells in the sound absorber 5 is 38 cells / 25 mm or more, the cell size is prevented from becoming excessively large, sound leakage is prevented, and sound absorption performance can be improved. If the number of cells in the sound absorber 5 is 50 cells / 25 mm or less, the cell size is prevented from becoming excessively small, a certain level of breathability is ensured, and sound absorption performance can be improved.

[0024] The cross-sectional area of ​​the sound absorber 5 in the tire meridian cross section is preferably 5% to 15% of the cross-sectional area of ​​the tire cavity 1a in the tire meridian cross section. Here, the cross-sectional area of ​​the sound absorber 5 is an area determined by the outer shape including the cells of the internal cavity. Furthermore, the cross-sectional area of ​​the tire cavity 1a is the area of ​​the space surrounded by the inner surface of the pneumatic tire 1 in a normal state and the outer surface of the rim R.

[0025] If the cross-sectional area of ​​the sound absorber 5 is 5% or more of the cross-sectional area of ​​the tire cavity 1a, it is possible to reliably achieve the sound absorbing effect of the sound absorber 5. If the cross-sectional area of ​​the sound absorber 5 is 15% or less of the cross-sectional area of ​​the tire cavity 1a, it is possible to suppress increases in cost, weight, and heat storage effect due to the sound absorber 5.

[0026] Although a particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment and can be modified and practiced in various ways.

[0027] [Note] The present invention is as follows.

[0028] [Invention 1] A pneumatic tire having a tread portion, A sponge-like sound absorbing material is disposed on the inner surface side of the tread portion, a ratio (H / T) of a hardness H (N) of the sound absorber at 23°C when compressed by 25% to a height T (mm) of the sound absorber in the tire radial direction is 1.0 to 2.5; The ratio (T / W) of the height T (mm) of the sound absorber to the width W (mm) in the tire axial direction is 0.25 to 1.20. Pneumatic tires.

[0029] [Invention 2] The pneumatic tire according to invention 1, wherein the ratio (H / T) of the sound absorber is 1.2 to 2.1.

[0030] [Invention 3] 3. The pneumatic tire according to claim 1 or 2, wherein the ratio (T / W) of the sound absorber is 0.65 to 1.13.

[0031] [Invention 4] 4. The pneumatic tire according to any one of claims 1 to 3, wherein the number of cells in the sound absorber is 38 to 50 cells / 25 mm.

[0032] [Invention 5] 5. The pneumatic tire according to any one of claims 1 to 4, wherein the cross-sectional shape of the sound absorber in a tire meridian cross section is rectangular.

[0033] [Invention 6] 6. The pneumatic tire according to any one of Inventions 1 to 5, wherein the cross-sectional area of ​​the sound absorbing body in the tire meridian cross section is 5% to 15% of the cross-sectional area of ​​the tire cavity in the tire meridian cross section.

[0034] [Invention 7] The pneumatic tire according to any one of the first to sixth aspects of the present invention, wherein the sound absorbing body is fixed to the inner surface side of the tread portion via a double-sided tape, an adhesive, a pressure-sensitive adhesive, or a sealant material.

[0035] [Invention 8] 8. The pneumatic tire according to any one of claims 1 to 7, wherein the sound absorbing body is formed from urethane foam. [Explanation of symbols]

[0036] 1 pneumatic tire 2 Tread section 5 sound absorbing body

Claims

1. A pneumatic tire having a tread portion, A sponge-like sound absorbing material is disposed on the inner surface side of the tread portion, a ratio (H / T) of a hardness H (N) of the sound absorber at 23°C when compressed by 25% to a height T (mm) of the sound absorber in the tire radial direction is 1.2 to 2.1; a ratio (T / W) of the height T (mm) of the sound absorber to the width W (mm) in the tire axial direction of the sound absorber is 0.65 to 1.13; The number of cells in the sound absorber is 38 to 50 per 25 mm; a cross-sectional area of ​​the sound absorbing body in the tire meridian cross section is 5% to 15% of a cross-sectional area of ​​the tire cavity in the tire meridian cross section; Pneumatic tires.

2. The pneumatic tire according to claim 1, wherein the ratio (T / W) of the sound absorber is 0.80 to 1.

00.

3. The pneumatic tire according to claim 1 or 2, wherein the sound absorber has a rectangular cross-sectional shape in a tire meridian cross section.

4. The pneumatic tire according to claim 1 , wherein the sound absorbing body is fixed to the inner surface side of the tread portion via a double-sided tape, an adhesive, a pressure-sensitive adhesive, or a sealant material.

5. The pneumatic tire according to claim 1 , wherein the sound absorbing body is formed from urethane foam.

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