JPH03193510A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce road noise by providing a rubber reinforcing layer extending radially outward inside a carcass on the side of an inner cavity of a tire in a bead part, and establishing the rubber reinforcing layer to be fixed times as high as height at the maximum width of the tire. CONSTITUTION:Carcass 8 formed of organic fiber cord turns around a bead core 2 to form a turning back part 6B, and a tire bead part 3 having a belt 7 arranged on the radial outside of the carcass 6 is provided with a rubber reinforcing layer 9 inside the carcass 6 opposite to an inner cavity 8 of the tire. The rubber reinforcing layer 9 is thicker in layer thickness at a central part and decreases its thickness toward an inside and an outside in a radial direction to form a crescent-shape. The height h1 of the rubber reinforcing layer is set to be 0.4 to 1.00 times as high as height at the maximum width of the tire.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pneumatic tire that can reduce road noise during running.

[Conventional technology]

In recent years, as vehicles have increased in speed and performance, there has been a demand for quieter running, and therefore tires mounted on vehicles must also have low noise characteristics.

On the other hand, noise caused by tires includes pattern noise,
In addition to skill noise, there is a wide range of road noise caused by the vibrations received from the road surface during driving, which are excited by the tread and sidewall parts and propagated to the tire rim through the bead. In order to reduce this, for example, soft rubber is used in the tread portion, or the cord angle is changed to reduce the vibration itself from the road surface.

[Al1 problem to be solved by the invention] However, with such conventional products, there are problems such as shortening the wear life and impairing driving performance, and furthermore, it has not been possible to obtain a sufficiently satisfactory road noise suppression effect. not present.

Therefore, the present inventors have conducted various studies on the mechanism of this propagation. As a result, vibrations are mainly transmitted to the rim using the carcass as a medium, and therefore, by reducing carcass tension around the bead portion, the vibration transmission coefficient of the carcass can be lowered, and road noise can be suppressed. As shown in FIG. It has been found that the tension acting on the material can be reduced.

This is because when the tire makes contact with the ground, the bead portion A curves and deforms along the flange R1 of the rim as shown in Fig. 3, and at that time, compressive strain is generated on the outside surface 82 of the bead portion, which is the inside of the curve. Tensile strain acts on the inner surface S1 of the bead portion. Therefore, the tension can be reduced by moving the carcass body B to the neutral side where the tension is neutral to the inner tank, that is, to the central region between the outer surface S2 and the inner surface S1.

That is, in the present invention, by providing a rubber reinforcing layer extending radially outward along the inner surface of the carcass body in the door portion, the carcass line of the carcass body can be shifted to the neutral side of strain. The purpose of the present invention is to provide a pneumatic tire that reduces road noise by reducing carcass tension and lowering its vibration transmission coefficient.

[Means to solve the problem]

In order to achieve the above object, the pneumatic tire of the present invention includes a carcass provided with a folded part that folds around the heat core at both ends of the main body extending from the tread part through the sidewall part to the bead core of the bead part; A belt layer layer consisting of at least two belt plies arranged on the radially outer side of the carcass and inside the trend part, and a bead apex arranged in an area surrounded by the main body part and the folded part of the carcass. At the same time, a rubber reinforcing layer is provided in the bead portion extending radially outward from near the bead core along the inner surface of the carcass facing toward the inner cavity of the tire. The reinforcing layer height hl, which is the radial height, is 0.4 times or more the maximum width point height H, which is the radial height from the bead bottom to the tire maximum width point of the sidewall portion, and 1. 0
It is set to be 0 times or less.

The rubber reinforcing layer has a JISA hardness of 80° or more and 10
00 or less and its maximum thickness is preferably 3 days or more and 10 m or less, and the rubber reinforcing layer has a reinforcing layer height hl greater than the bead apex height h2, and a cross-sectional shape of approximately crescent. It is better to make it as follows.

[Effect]

The bead portion of the pneumatic tire configured in this manner is provided with a rubber reinforcing layer extending radially outward from the vicinity of the bead core inside the carcass main body portion.

Therefore, in the carcass, the carcass line has shifted relative to the center region side, that is, the neutral side where tensile strain and compressive strain are neutral, with respect to the bead thickness including the rubber reinforcing layer, and the bead line when touching the ground. During deformation, the tension acting on the body of the carcass can be reduced.

Furthermore, this reduction in tension reduces the vibration transmission coefficient of the carcass, suppresses the propagation of vibrations excited by the sidewalls, etc. to the rim, and reduces road noise.

Further, such a rubber reinforcing layer must be provided in the area where the deformation occurs, that is, in the area from the tire edge to a height of 0.4 times or more and 1.00 times or less of the maximum width point height of the tire.

In addition, in the present invention, even when simply adding a rubber reinforcing layer to the inside of the carcass of a conventional tire and increasing the total bead thickness at the bead portion, the carcass line can be moved to the center side relative to the bead thickness. This can reduce the tension in the carcass. It is also possible to reduce the thickness of the outer side of the carcass body according to the rubber thickness of the rubber reinforcing layer and shift the carcass line absolutely to the neutral side. It can be maintained at the same time as conventional tires.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

In the figure, the pneumatic tire l has a pair of dovetail portions 3.3 through which the bead core 2 passes, a sidewall portion 4.4 extending radially outward from each bead portion 3, and a trend portion 5 connecting both ends of the sidewall portions 4.4. A carcass 6 is stretched between the bead portions 3 and 3, and a rubber member extending radially outward along the inner surface of the carcass 6 facing the tire inner cavity 8 is provided in the bead portion 3. A reinforcing layer 9 is provided.

The carcass 6 has a toroidal main body portion 6 extending from the tread portion 5 through the sidewall portion 4 to the bead portion 3.
A has a folded part 6B that folds around the bead core 2 from the inside to the outside on both sides of the bead core 2, and between the main body part 6A and the folded part, a tapered part extending outward in the radial direction from the bead core 2 has, for example, JrSA hardness. A bead apex IO made of hard rubber with a diameter of 60" to 90" is interposed to increase the tire's lateral rigidity.

The carcass 6 is formed from at least one carcass ply in a radial or semi-radial arrangement with carcass cords inclined at an angle of 65 to 90 degrees with respect to the tire equator, and the carcass cord is made of nylon, polyester, rayon, etc. An organic fiber cord using aromatic polyamide or the like is preferably employed.

Further, a belt layer 7 is wound around the outside of the carcass 6 in the tire circumferential direction.

The belt layer 7 is made of at least two high-strength belt cords having low elongation and high elastic modulus, such as steel fiber cords and aromatic polyamide fiber cords, arranged at an angle of, for example, 35 degrees or less with respect to the tire equator, in this example. Here, it is formed from two belt plies 7A and 7B. Furthermore, the belt layer 7 has a maximum weight of 0.8 times or more of the tread width, reinforces the tread portion 5 with a hoop effect that almost extends to the tread, and increases tire rigidity and improves tire running performance and handling. Stability performance etc. have been improved.

In the present invention, when the bead deforms, the carcass 6
In order to reduce the tension acting on the main body 6A, the bead portion 3
The rubber reinforcing layer 9 is arranged inside the carcass 6 facing the tire inner cavity 8.

As shown in an enlarged view in FIG. 2, the rubber reinforcing layer 9 has an inner portion extending radially inwardly and outwardly of the thick central portion 9A, with the thickness gradually decreasing toward the radially inward and outward directions, respectively. 9B and an outer portion 9C, the cross section has a substantially crescent shape, and extends radially outward from the vicinity of the bead core 2, in this example, from the side of the bead core 2.

In this example, the bead portion 3 has a rubber thickness of the bead apex 10 in order to prevent a decrease in durability due to an increase in the volume of the bead portion 3 due to the arrangement of the rubber reinforcing layer 9 and, as a result, increased bead heat generation. By reducing the thickness, the increase in bead thickness is suppressed. Moreover, in this example, the main body part 6A passes through the bead part 3 in the central region within 20% of the bead thickness from its thickness center C, and therefore absolutely shifts to the neutral side of strain during bead deformation. This eliminates the tension acting on the carcass 6.

In addition, in order to prevent the bending rigidity of the bead portion 3 from decreasing due to the shift of the carcass line to the neutral side of strain and the decrease in the thickness of the bead apex 10, the rubber reinforcing layer 9 has a JISA hardness. Formed using hard rubber with a diameter of 80″ or more and 100° or less,
The maximum thickness t is set to 3 mm or more and 10 m or less.

Note that if the JISA hardness is less than 80°, the bending rigidity will be insufficient, and as a result, the amount of bead deformation will increase and the tension in the carcass 6 will increase practically, but the tire running performance, steering stability, etc. will decrease.

Furthermore, if the JISA hardness exceeds 100°, it will be difficult to manufacture the tire, and the difference in tightness between the rubber reinforcing layer 9 and the surrounding rubber will be too large, which will easily lead to rubber peeling.

If the maximum thickness t is less than 3 ws, the amount of shift to the neutral side will be small, and the tension in the carcass 6 will not be sufficiently reduced, and if it exceeds 10 days, it will be difficult to manufacture the tire.

Note that such a rubber reinforcing layer 9 needs to be formed in almost the entire area Q where bead deformation occurs, and therefore, the rubber reinforcing layer 9 has a reinforcing layer height hl, which is the height in the radial direction from the bead bottom. 0.4 times or more of the tire maximum width point height H and 1.
It is set to be 0 times or less. Note that the tire maximum width point height H is the radial height from the bead bottom of the tire maximum midpoint where the tire protrudes most outward in the axial direction of the tire. Note that if it is less than 0.4 times the tire maximum width point height H, the effect of reducing the vibration transmission coefficient of the carcass 6 will be poor, and if it exceeds 1.0 times, vibrations will be transmitted through the rubber reinforcing layer 9 as a medium. This easily worsens road noise and excessively increases tire rigidity, reducing ride comfort.

Further, it is preferable that the bead apex height h2, which is the height in the radial direction of the bead apex 10, be smaller than the reinforcing layer height hl, thereby reducing the transition of the main body portion 6A over the region Q to the neutral side. to facilitate
In addition, since the rubber reinforcing layer 9 has a substantially crescent-shaped cross section as described above, it can alleviate strain and stress concentration during bead deformation and improve its durability.

In the present invention, the rubber reinforcing layer 9 may be formed without reducing the thickness of the bead apex 10; in such a case, when the thickness is increased, the carcass line will be on the neutral side of distortion with respect to the bead thickness. It is possible to move relatively to Note that the rubber reinforcing layer 9 may be provided with, for example, a reinforcing brace having a reinforcing cord on its inner surface, and in such a case, the tension acting on the carcass 6 on the first surface can be further reduced.

〔Concrete example〕

A tire having the tire structure shown in FIG. 1 and having a tire size of 185/70R14 based on the specifications shown in Table 1 was prototyped, and the road noise of this tire when running on an actual vehicle was compared with a conventional tire. As shown in FIG. 4, the conventional tire has a one-domain structure, and its contour shape is the same as that of the example tire. Also, for road noise, set the road noise evaluation road to 50.
The noise when running at km/h is expressed as an index value with the conventional product set to 100, and the values are much superior.

〔Effect of the invention〕

As mentioned above, the pneumatic tire of the present invention is provided with a rubber reinforcing layer extending along the inner surface of the carcass at the bead portion, so the carcass line can be shifted to the neutral side of strain, reducing carcass tension and transmitting vibration. Road noise can be reduced by lowering the coefficient.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is an enlarged sectional view of the bead portion, Fig. 3 is a diagram illustrating bead deformation, and Fig. 4 is a sectional view showing the prior art. It is a diagram. 2-bead core, 3-bead part, 4-side wall part, 5-trend part, 6--carcass, 6
A--Body part, 6B--Folded part, 7-Belt layer, 7A, 7B--Belt ply, 8--Tire inner cavity, 9--Rubber reinforcing layer.

Claims (1)

[Scope of Claims] 1. A carcass provided with folded parts for folding around the bead core at both ends of the main body extending from the tread part through the sidewall part to the bead core of the bead part; a belt layer consisting of at least two belt plies arranged inwardly of the carcass; and a bead apex arranged in a region surrounded by the main body part and the folded part of the carcass;
A rubber reinforcing layer is provided extending radially outward from the vicinity of the bead core along the inner surface of the carcass facing toward the inner cavity of the tire, and the reinforcing layer has a height in the radial direction from the bead bottom of the bead portion of the rubber reinforcing layer. The height h1 is set to be at least 0.4 times the maximum width point height H, which is the height in the radial direction from the bead bottom to the tire maximum width point of the sidewall portion, and 1.
Pneumatic tires with a temperature of 00 times or less. 2 The rubber reinforcing layer has a JISA hardness of 80° or more and 1
00° or less, and the maximum thickness is 3mm or more and 10mm
The pneumatic tire according to claim 1, characterized in that: 3. The rubber reinforcing layer has a thick central portion where the reinforcing layer height h1 is larger than the bead apex height h2 which is the radial height of the bead apex from the bead bottom, and has the maximum thickness. Claim 1 or 2, wherein the radially inner part and the outer part have a substantially crescent-shaped cross section with the thickness decreasing toward the radially inward and outward sides, respectively.
Pneumatic tires listed.