JP2840183B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of reducing passing noise.

[0002]

2. Description of the Related Art In recent years, as noise outside a vehicle has become a major social problem, attention has been paid to tire noise, which is one factor of vehicle noise, and development of low-noise tires has been demanded.

The sources of noise generated from tires include:
For example, air column resonance generated by air passing through a column formed by a tread groove and the ground when a tire comes into contact with the ground is known, and tread patterns have been improved to reduce the air column resonance. .

[0004]

However, there is a limit in suppressing noise only by improving the tread pattern, and it is necessary to take measures for the tire structure other than the tread pattern in order to further reduce the noise. .

[0005] In the tire structure, vibration of the belt layer and vibration of the sidewall portion are considered. As a result of the inventor's repeated investigation and research into the vibration generation factors on the tire structure surface , it was found that even the vibration of the sidewall portion can be reduced by suppressing the vibration of the belt layer.

Further, by sandwiching an elastic rubber sheet between a plurality of belt plies forming a belt layer, the energy of bending vibration of the belt layer is converted into thermal energy by the rubber sheet. A damping effect can be obtained. I knew it.

An object of the present invention is to provide a pneumatic tire capable of reducing passing noise during running, based on providing an isolation rubber layer between belt plies of a belt layer.

[0008]

According to the present invention, there is provided a carcass which is folded from a tread portion through a sidewall portion and around a bead core of a bead portion, a carcass disposed inside the tread portion and outside a radius of the carcass, and A belt layer composed of a belt ply, and an isolating rubber layer interposed between the belt plies and composed of a rubber composition, and the rubber thickness t of the isolating rubber layer is set to a tread surface at a tire equatorial plane of a tread portion. and 0.02 times the tread thickness T leading to tire cavity surface from a 0.3 times or less, and the interval
The rubber release layer contains short fibers and has an internal loss (tan δ).
0.15 or less, complex elastic modulus (E *) of 100 kgf / cm ²
Formed using a reinforced rubber composed of the above rubber composition
It is a pneumatic tire characterized by the above.

[0009] The separating rubber layer may be formed by one belt ply piece continuous in the tire axial direction.
It can also be formed by a divided ply piece divided into a plurality of pieces in the tire axial direction.

[0010]

The belt layer is formed by a plurality of belt plies, and an isolation rubber layer made of a rubber composition is provided between the belt plies.

By providing such an isolating rubber layer, as shown in FIGS. 6A and 6B, the isolating rubber layer b undergoes shear deformation in the shearing direction with respect to the bending vibration m of the belt layer b. As a result, the vibration energy is converted into heat energy in the isolation rubber g. As a result, the vibration of the belt layer b is suppressed, and the passing noise is reduced.

The rubber thickness t of the isolation rubber layer is at least 0.02 times and at most 0.3 times the tread thickness T.
If the rubber thickness t is less than 0.02 times the tread thickness T, it cannot contribute to suppressing the vibration of the belt layer, and if it exceeds 0.3 times, the fuel efficiency is reduced by increasing the tire weight. And it will be inferior in durability.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, a pneumatic tire 1 includes a tread portion 2, a pair of sidewall portions 3, 3 extending inward in the tire radial direction from both sides thereof, and a bead portion 4 extending inward of the sidewall portion 3. Have.

The pneumatic tire 1 has a main body 6 extending from the tread portion 2 to the bead portion 4 through the sidewall portion 3.
1A, a carcass 6 having a folded portion 6b that turns around the bead core 5 from the inside to the outside in the tire axial direction, and a belt layer 7 disposed outside the carcass 6 and inside the tread portion.

The belt layer 7 includes an inner belt ply 7A disposed radially outside the carcass 6 and adjacent to the carcass 6, and an outer belt ply 7B disposed outside the inner belt ply. The two belt plies 7 are provided between the inner and outer belt plies 7A and 7B.
An isolation rubber layer 9 for isolating A and 7B is provided.

In this embodiment, the main body 6a and the folded portion 6b of the carcass 6 are located radially outward of the bead core 5.
Between them, a bead apex 8 made of hard rubber having a triangular cross section is set up.

In the present embodiment, the carcass 6 comprises two carcass plies 6A and 6B.
A, 6B is formed as a radial or semi-radial arrangement in which carcass cords made of organic fibers such as nylon, polyester, rayon, and aromatic polyamide are juxtaposed at an angle of 75 to 90 ° with respect to the tire equator C,
In addition, the carcass cords are arranged between the carcass plies 6A and 6B so as to cross each other. In this example,
The height from the bead base line at the tip of the folded portion 6b is formed as a high turn-up that is larger than the tip height of the bead apex.

The belt layer 7 includes the inner belt ply 7A and the outer belt ply 7B as described above. Each of the belt plies 7A and 7B is made of an organic fiber such as nylon, polyester, rayon, or aromatic polyamide or steel. 10 to 45 ° with respect to the tire equator C
And the belt plies 7A and 7B are arranged in a direction crossing each other.

In the present embodiment, the inner belt ply 7A is formed to be slightly wider than the outer belt ply 7B, and the ply width W of the inner belt ply 7B is formed.
B is formed to be 0.8 to 0.95 times the tread width WT.

The separating rubber layer 9 is equal to or less than the width WB of the innermost belt ply, ie, the widest belt ply forming the belt layer 7, and is equal in the present embodiment. Is in a range of 0.02 times or more and 0.30 times or less of the tread thickness T from the tread surface 2A on the tire equator C surface of the tread portion 2 to the tire lumen surface 2B.

[0021] The isolation rubber layer 9 is formed by adding short fibers to the base rubber.
It consists of mixed reinforced rubber, for example,In compositionI'll show you
It is formed by such a rubber composition. In addition, as short fiber
Is made of nylon, aromatic polyamide fiber, cotton, etc.
Machine fiber, its diameter is 1μ ~ 0.1mm, length is
It is preferably in the range of 20 μm to 2 mm.

[0022]

[Table 1]

[0023] isolating rubber layer 9, a complex modulus as viscoelastic properties of its (E *) of 100 kgf / cm ² or more and preferably 400 kgf / cm ² or less, and internal loss (tan [delta]) 0.15 or less And

As described above, the isolating rubber layer 9 is formed by adding short fibers to the base rubber to form the complex elastic modulus (E).
*), The storage modulus (E ′) and the loss modulus (E ″), which are vector elements, both increase, resulting in a complex modulus (E
*) Will increase. By increasing the complex elastic modulus (E *), it is possible to prevent the occurrence of the cornering force from decreasing and to maintain the running stability. When the complex elastic modulus (E *) is less than 100 kgf / cm ² , the occurrence of cornering force is reduced. When the complex elastic modulus (E *) exceeds 400 kgf / cm ² , the viscoelasticity of the rubber layer 9 is lost and the vibration damping effect may not be obtained. .

Further, by adding short fibers, the storage modulus (E ') is further increased more than the loss modulus (E "). As a result, the internal loss (tan) is increased.
δ) is reduced, and the rolling resistance is also reduced. If the internal loss (tan δ) exceeds 0.15, the rolling resistance tends to increase.

The damping effect also tends to increase as the loss elastic modulus (E ″) increases. This is because the addition of short fibers causes slip and entanglement between the rubber and the fibers and between the fibers, resulting in friction. Thereby, the vibration energy is efficiently absorbed into the isolation rubber layer 9.

Further, in this embodiment, the separating rubber layer 9 has a central ply piece 11 along the tire equator C, and both sides of the central ply piece 11 in the tire axial direction and adjacent to the central ply piece 11. Two side ply pieces 12, 12 to be arranged
Are formed by three divided plies 13 consisting of

Further, as shown in FIG.
In 1, the short fibers are oriented in the meridian direction, while in the ply pieces 12, 12 on the two sides, the short fibers are oriented in the tire circumferential direction. The direction of these short fibers is
The orientation is oriented within a range of 0 to 20 ° with respect to each designated direction.

This is based on the following reason. When an in-plane bending moment acts in the direction of arrow B shown in FIG. 2 when the tire turns, a compressive stress is applied to the ply piece 12 on the bending side, and a side opposite to the bending. Tensile force acts on each of the ply pieces 12. Therefore, in the shoulder portion of the tread portion 2, the ply pieces 12 and 12 on the side orient the short fibers in the circumferential direction, so that the isolation rubber layer 9 increases the expansion and contraction rigidity in the tire circumferential direction, and generates a larger stress. Make it possible.

On the other hand, in the central portion of the tread portion 2, since the central ply piece 11 has short fibers arranged in the tire axial direction, compression from the side ply pieces 12, 12 can be prevented, and in-plane bending can be prevented. A large moment can be maintained. Therefore, the isolation rubber layer 9 is configured as described above .
What, tire, it is possible to generate a larger cornering force, without increasing rolling resistance, further without cornering force is reduced, it is possible to reduce the pass-by noise of the tire.

The width WM of the central ply piece is preferably 1/3 to 1/2 times the total width WG of the isolation rubber layer 9. The separating rubber layer 9 can also be formed by a single ply piece in which short fibers are aligned in a certain direction, and further formed by mixing short fibers in a random direction without aligning the short fibers in one ply piece. It is also possible.

Further, in this embodiment, a band layer 10 for preventing the lifting of the belt layer 7 is provided outside the belt layer 7 in the radial direction.

FIGS. 3 to 5 show another embodiment of the isolation rubber layer 9. FIGS. 3A and 3B both show one ply piece 14.
Thus, an isolation rubber layer 9 is formed. (A) is width WG
Is arranged at the center of the tread portion 2 by one wide ply piece 14 substantially equal to the belt width WB.
The rubber layer 9 is isolated by the small width ply pieces 14 respectively.
Is formed.

FIG. 4 shows three ply pieces 14... Arranged with a gap in the tire axial direction, and FIG. 5 shows two ply pieces 14, 14 having a small width. Part.

Further, the belt layer may be formed by laminating three or more belt plies, and the separating rubber layer having the above-mentioned configuration may be disposed between any two adjacent belt plies. The present invention can be modified into various embodiments.

[0036]

[Specific Example] A tire having a tire size of 205 / 55R15 and having the structure shown in FIG.
Isolated tires (Examples 1 and 2), rubber of composition B and C
The tires used for the rubber layer (Comparative Examples 1 and 2) were prototyped according to the specifications shown in Table 2 and their performance was investigated. For comparison, a test was also performed on a tire having a conventional configuration without a separating rubber layer (conventional example), and a comparison was made. The test conditions are as follows. 1) Passing noise The vehicle was mounted on a straight test course with a passing speed of 60 km / H and a distance of 50 m on a straight-line test course. The maximum passing noise was measured by a microphone installed at a point 7.5 m laterally from the running center line and at a height of 1.2 m from the test road surface.

2) Rolling resistance Rolling resistance was measured using a rolling resistance tester, and was indicated by an index with the conventional example being 100. The smaller the value, the better the rolling resistance.

3) Cornering power The cornering power was measured using a flat belt type laboratory tester, and was indicated by an index with the conventional example being 100. The higher the value, the better. Table 2 shows the test results.

[0039]

[Table 2]

[0040]

As described above, the pneumatic tire of the present invention has the following features.
Mix short fibers between the belt plies forming the belt layer.
Basic and in that a isolation rubber layer of rubber composition
As a result, it is possible to reduce the passing noise during traveling while maintaining the balance of the tire performance .

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an example of the configuration of the isolation rubber layer.

FIG. 3 is a cross-sectional view showing another embodiment of the isolation rubber layer.

FIGS. 4A and 4B are cross-sectional views showing another embodiment of the isolation rubber layer.

FIG. 5 is a sectional view showing another embodiment of the isolation rubber layer.

FIGS. 6A and 6B are cross-sectional views schematically showing a state of vibration of a belt layer, wherein FIG. 6A shows a state without vibration and FIG.

[Description of Signs] 2 Tread portion 2A Tread surface 2B Lumen surface 3 Side wall portion 4 Bead portion 5 Bead core 6 Carcass 7 Belt layer 7A Belt ply inside 7A Belt ply outside 9B Isolation rubber layer 11 Center ply piece 12 side Ply piece 13 split ply 14 ply piece C tire equator T tread thickness t rubber thickness

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-143703 (JP, A) JP-A-60-6007 (JP, A) JP-A-1-160705 (JP, A) JP-A-1- 160708 (JP, A) JP-A-61-119405 (JP, A) JP-A-5-104678 (JP, A) JP-B-50-25204 (JP, B1) (58) Fields investigated (Int. ⁶ , DB name) B60C 9/18

Claims (4)

(57) [Claims] 1. A carcass which is folded from a tread portion through a sidewall portion around a bead core of a bead portion, a belt layer which is disposed inside the tread portion and outside the radius of the carcass and comprises a plurality of belt plies, and An isolating rubber layer interposed between the belt plies and made of a rubber composition, and having a rubber thickness t of the isolating rubber layer, the tread extending from the tread surface on the tire equatorial plane of the tread portion to the tire lumen surface. 0.02 times or more and 0.3 times or less of the thickness T , and
The isolation rubber layer contains short fibers and has an internal loss (tan).
δ) is 0.15 or less, and the complex elastic modulus (E *) is 100 kgf.
/ Cm ² or more using a reinforced rubber made of a rubber composition
A pneumatic tire characterized by being formed . 2. The isolation rubber layer comprises a single ply piece that is continuous in the axial direction of the tire within a range equal to or less than the width of the widest belt ply forming the belt layer. The pneumatic tire as described. 3. The separating rubber layer is formed of a plurality of divided ply pieces in the tire axial direction within a range not more than the width dimension of the widest belt ply forming the belt layer. 2. The pneumatic tire according to 1. Wherein said isolating rubber layer, by three split ply piece consisting of a ply piece on the side to be positioned adjacent to the tire axial direction sides of the middle ply piece and the central ply piece along the tire equator The air according to claim 3 , wherein the formed ply piece orients the short fibers in the tire meridian direction while the central ply piece orients the short fibers in the tire circumferential direction. Containing tires.