Pneumatic tire

Abstract

The present invention is a pneumatic tire (1) having a tread portion (2). In a pneumatic tire (1), a spongy sound-absorbing body (5) is disposed on the inner surface side of a tread portion (2). The ratio (H / T) of the hardness H (N) of the sound-absorbing body (5) at 23 DEG C under 25% compression to the height T (mm) of the sound-absorbing body (5) in the radial direction of the tire is 1.0-2.5. The ratio (T / W) of the height T (mm) of the sound-absorbing body (5) to the width W (mm) in the axial direction of the tire is 0.25-1.20.

Description

Technical Field

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

[0002] Conventionally, a pneumatic tire having a sponge-like sound absorber fixed to the inner surface side of the tread portion has been known. For example, Patent Document 1 below proposes a pneumatic tire capable of reducing road noise for a long time by restricting the height and shape of the sound absorbing body, the hardness, tensile strength, and specific gravity of the sponge material. Prior Art Documents Patent Documents

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-306302 Summary of the Invention Problems to be Solved by the Invention

[0004] However, in a pneumatic tire with a sound absorber fixed thereto, by fixing a sponge-like sound absorber to the inner surface side of the tread portion, due to the influence of increased cost, increased weight, and heat storage, various performances such as cost performance, handling stability performance, low fuel consumption performance, and durability performance may deteriorate. Therefore, a pneumatic tire capable of more efficiently absorbing sound is desired.

[0005] The present invention has been made in view of the above actual situation, and an object thereof is to provide a pneumatic tire capable of improving noise performance by efficiently absorbing sound. Means for Solving the Problems

[0006] The present invention is a pneumatic tire, characterized in that it is a pneumatic tire having a tread portion, a sponge-like sound absorber is disposed on the inner surface side of the tread portion, and 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 tire radial direction 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) of the tire in the axial direction is 0.25 to 1.20. Effects of the Invention

[0007] The pneumatic tire of the present invention can efficiently absorb sound and improve noise performance by having the above-described configuration. Brief Description of the Drawings

[0008] Figure 1 A cross-sectional view showing an embodiment of the pneumatic tire of the present invention. Description of Reference Numerals 1: Pneumatic tire 2: Tread portion 5: Sound absorber. Detailed Description of the Invention

[0009] ​Hereinafter, a mode of implementation of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 It is a tire meridian cross-sectional view including the rotation axis of the pneumatic tire 1 representing the normal state of the present embodiment. Here, the "normal state" means a state without load assembled on a normal rim and adjusted to a normal internal pressure. Hereinafter, unless otherwise specified, the dimensions and the like of each part of the pneumatic tire 1 are values measured in this normal state.

[0010] The "normal rim" means: when there is a standard system including the standard on which the pneumatic tire 1 is based, the rim R specified for each tire by this standard. For example, it refers to the "standard rim" of JATMA, the "Design Rim" of TRA, and the "Measuring Rim" of ETRTO. When there is no standard system including the standard on which the pneumatic tire 1 is based, the "normal rim" refers to the rim R with the smallest rim diameter and the smallest rim width among the rims R that can be assembled without air leakage.

[0011] The "normal internal pressure" means: when there is a standard system including the standard on which the pneumatic tire 1 is based, the air pressure specified for each tire by each standard, which refers to the "maximum air pressure" of JATMA, the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" of TRA, and the "INFLATION PRESSURE" of ETRTO. When there is no standard system including the standard on which the pneumatic tire 1 is based, the "normal internal pressure" refers to the air pressure specified for each tire by the manufacturer or the like.

[0012] As Figure 1 shown, the pneumatic tire 1 of the present embodiment includes: a tread portion 2 extending in a ring 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 inner sides of the sidewall portions 3 in the tire radial direction.

[0013] In the tread portion 2 of the present embodiment, the outer surface side in the tire radial direction constitutes a ground contact surface 2s that contacts the road surface during driving. The sidewall portion 3 preferably extends from both sides of the tread portion 2 in the tire axial direction to the inside in the tire radial direction. Between the tread portion 2 and the sidewall portion 3, for example, a buttress portion is provided. The bead portion 4 includes, for example, a portion that contacts the rim R when assembled on the rim.

[0014] In the pneumatic tire 1 of the present embodiment, a sponge-like sound absorber 5 is disposed on the inner surface side of the tread surface 2. Ideally, the sponge-like sound absorber 5 is a porous material having a plurality of pores inside. Such a sound absorber 5 can absorb vibrations of a specific frequency range, and can improve the noise performance of the pneumatic tire 1.

[0015] The ratio (H / T) of the hardness H (N) of the sound absorber 5 at 25% compression at 23 °C to the height T (mm) of the sound absorber 5 in the tire radial direction is preferably 1.0 to 2.5. In addition, 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 25% compression at 23 °C is a value measured according to the provisions of JIS K6400-2.

[0016] The natural vibration frequency of such a sound absorber 5 is close to the resonance frequency of the pneumatic tire 1, and by resonating with the pneumatic tire 1, the noise around 160 to 250 Hz can be attenuated, and the sound absorption efficiency can be greatly improved. Therefore, the pneumatic tire 1 of the present embodiment can absorb sound efficiently and improve the noise performance.

[0017] That is, in the pneumatic tire 1 of the present embodiment, by limiting the size and hardness of the sound absorber 5 in a specific ratio, the pneumatic tire 1 and the sound absorber 5 can resonate without additionally providing a weight or the like. From this point of view, 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. In addition, 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 further preferably 0.80 to 1.00.

[0018] As a more preferred embodiment, the sound absorber 5 is fixed to the inner surface side of the tread surface 2 by a double-sided tape, an adhesive, an adhesive agent, or a sealant material. Such an installation operation of the sound absorber 5 is easy, which helps to reduce the manufacturing cost. In addition, the sound absorber 5 can also be disposed, for example, in a manner not fixed to the inner surface side of the tread surface 2.

[0019] The cross-sectional shape of the sound absorber 5 in the tire meridian cross-section of the present embodiment is rectangular. Such a sound absorber 5 is easy to resonate with the pneumatic tire 1, and can improve the sound absorption performance. In addition, such a sound absorber 5 is easy to manufacture, which helps to reduce the manufacturing cost.

[0020] The sound absorber 5 of the present embodiment is continuously provided in the tire circumferential direction. Such a sound absorber 5 can evenly exert the sound absorption effect over the entire circumference of the pneumatic tire 1. In addition, the sound absorber 5 is not limited to such a manner. For example, in the tire circumferential direction, there may be a partially discontinuous portion, or a plurality of sound absorbers 5 may be fixed.

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

[0022] The height T of the sound absorber 5 is preferably 10 to 80 mm. By making the height T of the sound absorber 5 10 mm or more, the sound absorber 5 can resonate with the pneumatic tire 1. By making the height T of the sound absorber 5 80 mm or less, the influence on the handling stability performance and the operation of assembling to the rim R can be suppressed.

[0023] The number of cells of the sound absorber 5 is preferably 38 to 50 cells / 25 mm. Here, the number of cells is a value measured according to Appendix 1 of JIS K6400-1. By making the number of cells of the sound absorber 5 38 cells / 25 mm or more, the size of the cells is suppressed from being too large, leakage of sound can be prevented, and the sound absorption performance can be improved. By making the number of cells of the sound absorber 5 50 cells / 25 mm or less, the size of the cells is suppressed from being too small, and a certain air permeability can be ensured, and the sound absorption performance can be improved.

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

[0025] By making the cross-sectional area of the sound absorber 5 5% or more of the cross-sectional area of the tire inner cavity 1a, the sound absorption effect brought by the sound absorber 5 can be surely exerted. By making the cross-sectional area of the sound absorber 5 15% or less of the cross-sectional area of the tire inner cavity 1a, an increase in cost, an increase in weight, and a heat storage effect brought by the sound absorber 5 can be suppressed.

[0026] The particularly preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments and can be implemented in various modified forms.

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

[0028] [Invention 1] A pneumatic tire, characterized in that it is a pneumatic tire having a tread portion, a sponge-like sound absorber is disposed on the inner surface side of the tread portion, the ratio (H / T) of the hardness H (N) of the sound absorber at 23°C and 25% compression to the 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.

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

[0031] [Invention 4] The pneumatic tire according to any one of Inventions 1 to 3, wherein the number of pores of the sound absorber is 38 to 50 per 25 mm.

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

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

[0034] [Invention 7] The pneumatic tire according to any one of Inventions 1 to 6, wherein the sound absorber is fixed to the inner surface side of the tread portion by a double-sided tape, an adhesive, an adherent or a sealant material.

[0035] [Invention 8] The pneumatic tire according to any one of Inventions 1 to 7, wherein the sound absorber is formed of polyurethane foam.

Claims

1. An inflatable tire, characterized in that, it is an inflatable tire having a tread surface, a sponge-like sound absorber is disposed on the inner surface side of the tread surface, the ratio H / T of the hardness H of the sound absorber at 25% compression at 23°C to the height T of the sound absorber in the tire radial direction is 1.0 to 2.5, the ratio T / W of the height T of the sound absorber to the width W in the tire axial direction is 0.25 to 1.20, the unit of H is N, and the units of T and W are mm.

2. The inflatable tire according to claim 1, wherein, the ratio H / T of the sound absorber is 1.2 to 2.

1.

3. The inflatable tire according to claim 2, wherein, the ratio T / W of the sound absorber is 0.65 to 1.

13.

4. The inflatable tire according to any one of claims 1 to 3, wherein, the number of pores of the sound absorber is 38 to 50 per 25 mm.

5. The inflatable tire according to any one of claims 1 to 3, wherein, the cross-sectional shape of the sound absorber in the tire meridian section is rectangular.

6. The inflatable tire according to any one of claims 1 to 3, wherein, the cross-sectional area of the sound absorber in the tire meridian section is 5% to 15% of the cross-sectional area of the tire inner cavity in the tire meridian section.

7. The inflatable tire according to any one of claims 1 to 3, wherein, the sound absorber is fixed to the inner surface side of the tread surface by a double-sided tape, an adhesive, an adherent or a sealant material.

8. The inflatable tire according to any one of claims 1 to 3, wherein, the sound absorber is formed of polyurethane foam.

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