JP7180225B2 - Pneumatic tire with sound damping body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pneumatic tire with a noise damper in which a noise damper made of a porous resin foam is arranged on the inner cavity surface of the tire.

In order to reduce the road noise of the tire, a pneumatic tire with a noise damper has been proposed in which a noise damper made of a sponge material (porous resin foam) is attached along the tire's circumferential direction to the inner cavity surface of the tire. (See Patent Document 1, for example). This damping body can reduce the energy of cavity resonance within the tire bore, which is the source of road noise.

It is believed that the higher the ratio of the volume of the sound damper to the total volume of the tire cavity, the greater the effect of reducing cavity resonance. It is rare. However, increasing the volume of the damping body results in an increase in cost. Moreover, as the contact area between the noise damper and the inner cavity surface of the tire increases, the heat storage capacity increases, causing thermal fatigue and reducing the durability.

In view of this situation, as a result of research conducted by the present invention, it was found that the cavity resonance sound is generated near the center of the tire bore.

From this,
(1) It is possible to enhance the effect of reducing cavity resonance noise by arranging the sound damper at a position near the center of the tire bore;
(2) Conversely, the position close to the inner cavity surface of the tire is weakly involved in reducing cavity resonance noise, and the amount of the porous resin foam can be reduced at this position;
was found.

Japanese Patent Application Laid-Open No. 2006-306302

Therefore, the present invention is based on providing the base of the noise damper through the leg portion extending from the inner cavity surface of the tire. An object of the present invention is to provide a pneumatic tire.

The present invention provides a pneumatic tire with a noise damper, comprising a pneumatic tire and a noise damper made of a porous resin foam disposed on the inner cavity surface of the pneumatic tire,
In the tire meridional section,
The sound damping body includes a base extending in a radial direction at a distance from the tire inner cavity surface, and legs extending from both ends of the base in the radial direction to the tire inner cavity surface,
The radial width Wb of the leg is in the range of 18-32% of the radial width Wa of the base.

In the pneumatic tire with a noise damper according to the present invention, it is preferable that the noise damper is arranged on the tread inner surface of the tire inner cavity surface.

In the pneumatic tire with a noise damper according to the present invention, at the tire equator position, the radial distance Ha from the tread inner surface to the radial inner surface of the base portion is greater than the radial distance HT from the tread inner surface to the bead baseline. It is preferably 20-50%.

In the pneumatic tire with a noise damper according to the present invention, it is preferable that the width Wa is 50 to 70% of the tire cross-sectional width WT.

In the pneumatic tire with a noise damper according to the present invention, the noise damper may be formed from a plurality of split pieces spaced apart in the tire circumferential direction.

In the pneumatic tire with a noise damper according to the present invention, it is preferable that the number of split pieces is 4-12.

In the present invention, the base of the noise damper is arranged at a distance from the tire bore surface via the leg extending from the tire bore surface. That is, in the noise damper, the base is arranged at a position (a position near the center of the tire bore) that is strongly involved in reducing cavity resonance noise. Therefore, the effect of reducing cavity resonance can be enhanced.

Further, a cavity surrounded by the leg portion and the base portion is formed at a position (position close to the inner cavity surface of the tire) which contributes less to the reduction of cavity resonance noise. Therefore, it is possible to reduce the amount of the porous resin foam while minimizing the decrease in the cavity resonance noise reduction effect. As a result, an increase in the cost of the noise damper can be suppressed. In addition, since the contact area between the noise damper and the inner cavity surface of the tire is reduced, the influence of heat is reduced, making it possible to suppress deterioration in durability due to thermal fatigue.

1 is a meridional cross-sectional view of a tire showing an embodiment of a pneumatic tire with a noise damper according to the present invention; FIG. FIG. 2 is a circumferential cross-sectional view along the tire equator of the pneumatic tire with a noise damper. It is a tire meridional section showing an enlarged tread portion together with a noise damper.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.
As shown in FIG. 1, a pneumatic tire T with a noise damper according to the present embodiment includes a pneumatic tire 1 and a noise damper 20 made of a porous resin foam disposed on the inner cavity surface 1s of the tire. equip.

As the pneumatic tire 1, one having a well-known structure can be adopted. The pneumatic tire 1 of this example includes a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a belt arranged radially outside the carcass 6 and inside the tread portion 2. a layer 7;

The carcass 6 is formed from one or more (one in this example) carcass plies 6A having carcass cords arranged at an angle of, for example, 75 to 90° with respect to the tire circumferential direction. The carcass ply 6A has folded portions 6b folded around the bead cores 5 at both ends of a main body portion 6a extending between the bead cores 5,5.

The belt layer 7 is formed of a plurality of (for example, two) belt plies 7A and 7B having belt cords arranged at an angle of, for example, 10 to 40° with respect to the tire circumferential direction. The belt plies 7A and 7B are laminated with the direction of inclination of the belt cords being different from each other. For the purpose of improving high-speed durability, a band layer (not shown) formed by spirally winding a band cord in the circumferential direction may be provided radially outward of the belt layer 7 .

Inside the carcass 6, an inner liner rubber layer 9 forming the inner cavity surface 1s of the tire is arranged. The inner liner rubber layer 9 is made of an air-impermeable rubber such as butyl rubber, and keeps airtightly filled air in the tire.

Then, a noise damper 20 made of a porous resin foam is adhered to the inner cavity surface 1s of the tire. In this example, the noise damper 20 is arranged on the tread inner surface 2s, which is the radially inner surface of the tread portion 2, in the tire inner cavity surface 1s.

As the porous resin foam forming the sound damping body 20, a foam obtained by foaming rubber and synthetic resin is employed. Examples of rubber foams include chloroprene rubber sponge, ethylene propylene rubber sponge, nitrile rubber sponge and the like. Examples of synthetic resin foams include polyurethane sponges (eg, ether polyurethane sponges, ester polyurethane sponges, polyether/ester polyurethane sponges, etc.) and polyethylene sponges (eg, polyethylene sponges, etc.). Polyether/ester-based polyurethane sponges are particularly suitable from the viewpoint of durability and quality stability.

In such a porous resin foam, the air bubbles on the surface and inside thereof can reduce the vibration energy of the cavity resonance sound generated in the tire inner cavity H, thereby reducing the road noise.

As shown in FIG. 1 , the noise damper 20 has a U-shaped cross section including a base portion 21 and leg portions 22 , 22 in a tire meridional cross section.

The base portion 21 extends in the radial direction at a distance from the tire inner cavity surface 1s (the tread inner surface 2s in this example). The leg portions 22 extend from both ends of the base portion 21 in the radial direction to the inner cavity surface 1s of the tire.

Therefore, the noise damper 20 is formed with a hollow portion 23 surrounded by the base portion 21, the leg portion 22, and the tire inner cavity surface 1s (the tread inner surface 2s in this example).

In such a noise damper 20, the base portion 21 is arranged at a position (a position near the center Hp of the tire inner cavity H) that greatly contributes to the reduction of cavity resonance noise. Therefore, the effect of reducing cavity resonance can be enhanced. Further, a cavity 23 is formed at a position (position close to the tire inner cavity surface 1s) that contributes less to the reduction of cavity resonance noise. Therefore, it is possible to reduce the amount of the porous resin foam while minimizing the decrease in the cavity resonance noise reduction effect, and suppress the increase in the cost of the noise damper 20 . In addition, since the contact area between the noise damper 20 and the inner cavity surface 1s of the tire is reduced, the influence of heat is reduced, and deterioration of durability due to thermal fatigue is suppressed.

The center Hp of the tire lumen H is defined as the centroid of the space (tire lumen H) surrounded by the bead base line BL and the tire lumen surface 1s in the tire meridional section.

As shown in FIG. 2, in the noise damper 20, the radial width Wb of the leg portion 22 is in the range of 18 to 32% of the radial width Wa of the base portion 21. As shown in FIG.

If the width Wb is less than 18% of the width Wa, the adhesive strength of the noise damper 20 to the inner cavity surface 1s of the tire tends to be insufficient, and the noise damper 20 tends to peel off. In addition, the strength of the leg portion 22 tends to be insufficient, which may cause crack damage. Conversely, if it exceeds 32%, the contact area between the noise damping body 20 and the tire inner cavity surface 1s increases, making it susceptible to heat, and the decrease in durability due to thermal fatigue cannot be sufficiently suppressed. . Moreover, since the volume of the hollow portion 23 is reduced, it is disadvantageous in terms of cost reduction. Also, when each sound damping body 20 (or a split piece 20A to be described later) is formed by cutting out from a single large porous resin foam material, by setting the width Wb to 25% or less of the width Wa, waste material is generated. can be reduced and productivity increased. Therefore, the upper limit of the width Wb is preferably 25% or less of the width Wa.

In the noise damper 20, at the position of the tire equator C, the radial distance Ha from the tread inner surface 2s to the radial inner surface of the base portion 21 is greater than the radial distance HT (shown in FIG. 1) from the tread inner surface 2s to the bead base line BL. ) is preferably 20 to 50%.

If the distance Ha is less than 20% of the distance HT, the base portion 21 is separated from the center Hp of the tire inner cavity H, making it difficult to obtain the cavity resonance noise reduction effect. Even if it exceeds 50%, the effect of reducing cavity resonance noise cannot be expected to increase further, and conversely, it is disadvantageous in terms of cost reduction. In addition, the strength of the sound damping body 20 itself tends to be insufficient. From this point of view, the lower limit of the distance Ha is preferably 25% or more of the distance HT, and the upper limit is preferably 40% or less, more preferably 35% or less.

In the noise damper 20, the width Wa is preferably 50 to 70% of the tire cross-sectional width WT (shown in FIG. 1). When the width Wa is less than 50% of the tire cross-sectional width WT, the effect of reducing cavity resonance tends to decrease. Even if it exceeds 70%, the effect of reducing the cavity resonance noise cannot be expected to increase further, and conversely, it is disadvantageous in terms of cost reduction. From such a viewpoint, the lower limit of the width Wa is more preferably 55% or more of the tire section width WT, and the upper limit is more preferably 65% or less.

The cross-sectional area S1 of the hollow portion 23 is preferably 22 to 47% of the cross-sectional area S2 of the sound damping body 20. FIG. The cross-sectional area S2 is the cross-sectional area of the porous resin foam of the sound damping body 20, and does not include the hollow portion 23. As shown in FIG. If the cross-sectional area S1 is less than 22% of the cross-sectional area S2, the proportion of the hollow portion 23 becomes too small, which is disadvantageous for cost reduction. Conversely, if it exceeds 47%, the strength of the sound damping body 20 itself tends to be insufficient.

From the viewpoint of securing the cross-sectional area S1 of the hollow portion 23, the radial height Hb of the leg portion 22 is preferably 50% or more of the radial distance Ha of the base portion 21. Note that the radial height Hb of the leg portion 22 is measured on the side facing the hollow portion 23 .

As shown in FIG. 2, in this example, the noise damper 20 is formed of a plurality of divided pieces 20A spaced apart in the tire circumferential direction.

Here, in the cavity resonance, there is a wave whose circumference at the center Hp of the tire inner cavity H is one wavelength. Therefore, by arranging the split pieces 20A every λ/4, it is possible to suppress the nodes and peaks of the wave and obtain the effect of reducing the cavity resonance. Therefore, the sound damping body 20 does not need to be formed continuously in the circumferential direction over the whole circumference of the tire, and by spacing at least four split pieces 20A in the tire circumferential direction, the cavity resonance noise can be reduced. can do.

Thus, by forming the sound damping body 20 with a plurality of divided pieces 20A spaced apart in the tire circumferential direction, compared to the sound damping body 20 that is continuous in the circumferential direction over the whole circumference of the tire, the porous resin The amount of foam used can be reduced, which can further contribute to cost reduction. Further, since the contact area between the sound damping body 20 and the tire inner cavity surface 1s is further reduced, thermal fatigue can be suppressed, which can further contribute to the improvement of durability.

When the split pieces 20A are distributed according to the force variation (FV) of the tire 1, the advantage of reducing the FV in the pneumatic tire T with a noise damper can be obtained. Further, by adjusting the intervals of the split pieces 20A in the tire circumferential direction, it is possible to obtain the advantage that the noise damper 20 can be formed for tires of various sizes using one type of split piece 20A.

The number of divided pieces 20A to be formed is preferably 4 or more, and the upper limit is preferably 12 or less, more preferably 8 or less.

Moreover, the circumferential length L of the split piece 20A is preferably in the range of 50 to 200 mm. Further, the total sum ΣL of the circumferential length L of the split pieces 20A is preferably in the range of 8 to 30% of the tire circumferential length L0 on the tire inner cavity surface 1s.

The sound damping body 20 can also be formed as an annular body extending continuously in the tire circumferential direction and having both ends in the tire circumferential direction approaching or abutting each other. When both ends are close to each other, it is preferable that the distance between the ends in the circumferential direction is 150 mm or less from the viewpoint of weight balance.

Although the particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be modified in various ways.

A pneumatic tire (tire size 225/65R17) with a noise damper having the basic configuration shown in FIG. Each tire was tested for cavity resonance, amount of porous resin foam, and high speed durability.

Each tire has substantially the same specifications except for the damping body. Ether-based polyurethane sponge (specific gravity 0.039) is used as a sound damper. The sound dampers of Comparative Examples 1 and 2 are of solid type with no cavity.

(1) Cavity resonance:
Test tires were mounted on all wheels of a vehicle (2000cc, FF domestic car) under the conditions of rim (17x7J) and internal pressure (230kPa), and the cavity resonance sound (road noise) when running at 100km/h was The sound pressure level of the peak value of the cavity resonance sound around 240 Hz was measured using a microphone installed at the ear position on the window side of the driver's seat. The evaluation was indicated by an increase or decrease value based on Comparative Example 1. A - (minus) sign means a reduction in cavity resonance.

(2) Amount of porous resin foam:
The total volume of the porous resin foam was measured and evaluated with an index based on Comparative Example 1 being 100. The larger the numerical value, the larger the amount of porous resin foam.

(3) High speed durability:
Using a drum running tester, the internal pressure (230 kPa) and load (6.67 kN) are used, starting at a speed of 80 km/h, increasing the speed by 10 km/h every 10 minutes of running, and peeling off the sound damper. The running time until damage occurred was measured. The evaluation was made by an index with Comparative Example 1 being 100. The higher the numerical value, the better the high-speed durability.

As shown in the table, it can be confirmed that the tire of the example can enhance the effect of reducing the cavity resonance noise while reducing the amount of the porous resin foam.

1 pneumatic tire 1s tire cavity surface 2s tread inner surface 20 noise damper 20A split piece 21 base 22 leg 23 cavity BL bead base line T pneumatic tire with noise damper

Claims (5)

A pneumatic tire with a noise damper, comprising: a pneumatic tire;
In the tire meridional section,
The sound damping body includes a base portion extending in a radial direction at a distance from the tire inner cavity surface, leg portions extending from both ends of the base portion in the radial direction to the tire inner cavity surface , and the base portion and the leg portions. and a cavity surrounded by the tire lumen surface,
The radial width Wb of the connecting portion of the leg portion with the tire inner cavity surface is in the range of 18 to 32% of the radial width Wa of the base portion,
The sound damping body is composed of a plurality of divided pieces spaced apart in the tire circumferential direction,
The pneumatic tire with a noise damper, wherein in each of the split pieces, the hollow portion penetrates the split piece over the entire range in the tire circumferential direction. The pneumatic tire with a noise damper according to claim 1, wherein the noise damper is arranged on the tread inner surface of the tire inner cavity surface. 3. The restrictor according to claim 2, wherein at the tire equator position, the radial distance Ha from the tread inner surface to the radial inner surface of the base is 20 to 50% of the radial distance HT from the tread inner surface to the bead base line. Pneumatic tire with sound body. The pneumatic tire with a noise damper according to any one of claims 1 to 3, wherein the width Wa is 50 to 70% of the tire cross-sectional width WT. The pneumatic tire with a noise damper according to any one of claims 1 to 4, wherein the number of split pieces is 4 to 12.

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