JPH1111109A - Pneumatic radial tire for passenger car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve stable maneuverability and comfortableness at the same time by placing a carcass auxiliary layer, which is formed by burying a lot of organic fiber cords into rubber, into a belt which is formed by burying many metallic cords arranged radially in parallel each other into rubber and by stacking the cords with circumferentially specified angle in the opposite direction. SOLUTION: This tire is equipped with a pair of right and left bead cores 1, a carcass 2 which is engaged with a right and left bead sections with being wound around the bead cores 1, and a belt 3 arranged radially outside of the crown section. The tire is formed with a pair of right and left radial cord layers which extend from the both bead sections to the both ends of the crown. In the belt 3, cord direction is inclined about 10-30 degree circumferentially of the tire, the cords are placed to be parallel with each other between layers, and distance between radial cord layers in the crown section is 5-70% of cross section width of the belt. A carcass auxiliary layer 4 which is formed by burying many polyester fiber cords in rubber is placed such that it is adjacent to the inside of the tire of the carcass 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a bead core provided on a pair of left and right bead portions, and a carcass wound around the bead core and moored at the bead portion. , A belt disposed radially outward of the crown portion of the carcass, and a pneumatic radial tire for a passenger car.

[0002]

2. Description of the Related Art A carcass ply of a typical conventional pneumatic radial tire for a passenger car is formed by embedding a large number of organic fiber cords, which are arranged in parallel and radially with each other, in rubber, and one bead. It is formed of a radial cord layer continuously extending from the portion to the other bead portion via the side portion and the crown portion. Generally, polyester cord or rayon cord is used for this organic fiber cord layer. One layer of organic fiber cord layer is used for a small size of a pneumatic radial tire for a car, but it is large. In size, more than one ply cord layer is used. Conventional typical pneumatic radial tires for passenger cars have a belt disposed radially outward of a crown portion of a carcass, and the belt has a cord direction at an angle of about 10 to 30 degrees with respect to the circumferential direction of the tire. At least two layers are arranged parallel to each other in the layers, and are stacked in such a manner as to be opposite to each other with the tire equator interposed therebetween.

[0003]

The steering stability performance and vibration riding comfort performance are important requirements for pneumatic radial tires for passenger cars, but it is generally required to improve the steering stability performance and vibration riding comfort performance at the same time. It is well known to those skilled in the art that tires which are extremely difficult and have excellent steering stability performance have poor vibration riding comfort performance, and conversely, if the vibration riding comfort performance is improved, the steering stability performance decreases.

[0004] It is an object of the present invention to provide a pneumatic radial tire for a passenger car that overcomes the above-mentioned difficulties and simultaneously improves steering stability performance and vibration riding comfort performance.

[0005]

In order to achieve the above object, a pneumatic tire according to the present invention comprises a bead core provided on a pair of left and right bead portions, and a right and left bead wound around the bead core. In a pneumatic tire including a carcass moored at a bead portion and a belt disposed radially outward of a crown portion of the carcass, (1) the carcass includes a plurality of carcasses arranged in parallel with each other and in a radial direction. It is made by embedding a metal cord in rubber, extending from the bead part on both sides to at least both ends of the crown via both side parts,
The belt is formed of a pair of left and right radial cord layers that terminate without exceeding the center of the crown. (2) The belts have cord directions at an angle of about 10 to 30 degrees with respect to the circumferential direction of the tire, and the belts are mutually separated in the layers. It is formed of at least two layers of metal cords buried in rubber in at least two layers, which are arranged in parallel with each other with the tire equator interposed therebetween and in opposite directions, and (3) adjacent to the carcass One carcass auxiliary layer extending continuously from one bead portion to the other bead portion is disposed, and the carcass auxiliary layer embeds a large number of organic fiber cords arranged in parallel and in a radial direction in rubber. A pneumatic radial tire for a passenger car, comprising: In order to achieve the above object, in the pneumatic tire of the present invention, it is preferable that the carcass auxiliary layer is arranged adjacent to the carcass inside the tire. In order to achieve the above object, in the pneumatic tire of the present invention, the interval between one end portion and the other end portion of the crown portion of the pair of left and right radial cord layers forming the carcass is equal to that of the belt. Preferably, it is 5 to 70% of the cross-sectional width. In order to achieve the above object, in the pneumatic tire of the present invention, the carcass is preferably formed of a radial cord layer formed by embedding a metal cord having a single twist structure in rubber.

The present invention seeks to increase the carcass rigidity as a whole by replacing the carcass conventionally formed of an organic fiber cord layer with a metal cord layer, thereby improving the steering stability of a pneumatic tire for a passenger car. Things. However, when the carcass of the conventional pneumatic tire for a passenger car is simply changed from the organic fiber cord layer to the metal cord layer, the cord direction is 10 times with respect to the circumferential direction of the tire.
A layer formed by embedding a large number of metal cords in rubber at least two layers, which are arranged parallel to each other in the layer at an angle of about 30 degrees and are opposite to each other across the tire equator line between the layers. The crown portion is formed of three metal cord layers extending in different directions from each other, so that the rigidity of the crown portion becomes too large and the vibration riding comfort performance deteriorates. Therefore, as described above, the pneumatic tire of the present invention has a carcass formed by a pair of left and right radial cord layers extending from the right and left bead portions to at least both end portions of the crown via both side portions and terminating without exceeding the crown central portion. Are formed. In this way, the radial cord layer continuously extending from one bead portion to the other bead portion is hollowed out at the crown portion, so that the tire crown portion is supple and the vibration riding comfort performance is improved. Have improved. It is to be noted that hollowing out the radial cord layer at the crown portion may cause the tire rigidity of the crown portion to be excessively reduced. Therefore, in the pneumatic tire of the present invention, a carcass auxiliary layer made of an organic fiber cord is provided adjacent to the carcass. Is arranged. Further, as described above, the pneumatic tire of the present invention forms a carcass with a radial cord layer formed by embedding a metal cord in rubber, so that the metal cord is rusted while the tire is being used. This may cause the durability of the tire to decrease. Therefore, in the pneumatic tire of the present invention, it is preferable that the carcass auxiliary layer made of the organic fiber cord is disposed adjacent to the carcass made of the metal cord inside the tire. In the pneumatic tire of the present invention, as described above, the interval from one end to the other end of the crown portion of the pair of left and right radial cord layers forming the carcass is 5 to 5 times the cross-sectional width of the belt. Preferably it is 70%. If this value is less than 5%, the tire stiffness of the crown portion will not be sufficiently reduced, and the initial goal of improving the vibration riding comfort performance will not be achieved. The distortion generated at the end of the crown portion of the carcass made of a metal cord increases, which causes a problem that the durability performance of the tire decreases. In the pneumatic tire according to the present invention, as described above, the carcass has a strength that is not reduced by fretting and has a certain degree of elongation.
It is preferably formed of a code layer.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, tires of Examples 1 to 3, a conventional tire and a comparative tire according to the present invention will be described with reference to the drawings. All tire sizes are PSR205 / 65R15.

FIG. 1 is a schematic cross-sectional view of the left half of the tire according to the first embodiment of the present invention. As shown in FIG. 1, the tire according to the first embodiment includes a pair of beads provided on a pair of right and left bead portions.
A pneumatic radial tire for a passenger car comprising a core 1, a carcass 2 wound around a bead core 1 and moored to left and right bead portions, and a belt 3 arranged radially outward of a crown portion of the carcass. is there. Carcass 2
A large number of steel cords 1 × 3 × 0.2 arranged in parallel with each other and in the radial direction are buried in rubber, and extend from the right and left beads to the crown via both side parts and exceed the center of the crown. It is formed of a pair of left and right radial cord layers ending without any damage, and the number of cords to be driven is 40/5 cm. The distance W1 from one end to the other end of the crown portion of the radial cord layer forming the carcass 2 is 10 mm,
Since the sectional width W2 of the belt 3 is 165 mm, the interval W1 between the radial cord layers is 6% of the sectional width W2 of the belt 3. The belt 3 is a two-layered belt in which the cord direction is arranged at an angle of 20 degrees with respect to the circumferential direction of the tire, and is arranged parallel to each other in the layers, and is interposed between the layers in opposite directions with respect to the tire equator. It is formed of a layer of steel cord embedded in rubber. For the belt 3, a steel cord having a wire diameter of 0.25 mm and a 1 × 5 structure is used, and the number of cords to be driven is 40/5 cm. As shown, one carcass auxiliary layer 4 extending continuously from one bead portion to the other bead portion is disposed adjacent to the carcass 2 inside the tire. This carcass auxiliary layer 4 is a layer in which a large number of 1000 d / 1 polyester fiber cords arranged in parallel and in the radial direction are embedded in rubber, and the number of cords to be driven is 40/5 cm. Belt reinforcing layers 5 are arranged radially outward of both ends of the belt 3 as shown in the figure. The belt reinforcing layer 5 is made of a nylon cord of 1260 d / 2 at an angle of 0 degree with respect to the circumferential direction of the tire, and the number of strikes is 40/5.
It is a layer embedded in rubber in cm.

The pneumatic tire of the second embodiment has a carcass 2
The distance W1 from one end to the other end of the crown portion of the radial cord layer forming 90 mm is 90 mm.
It is almost the same as the pneumatic tire of Example 1 except that Since the sectional width W2 of the belt 3 is 165 mm, which is the same as that of the pneumatic tire of the first embodiment, the interval W1 between the radial cord layers is 55% of the sectional width W2 of the belt 3.

The pneumatic tire of Example 3 is substantially the same as the pneumatic tire of Example 2 except that the carcass auxiliary layer 4 is formed of a 1000 d / 2 polyester fiber cord.

In the conventional pneumatic tire, the carcass 2 is formed by laminating two 1500 d / 2 polyester fiber cord layers, and extends from one bead portion to the other bead portion via a side portion and a crown portion. It is almost the same as the pneumatic tire of the first embodiment except that it is formed of a radial cord layer extending continuously and does not include the carcass auxiliary layer 4.

In the pneumatic tire of the comparative example, the carcass 2 is formed of a radial cord layer extending continuously from one bead portion to the other bead portion via a side portion and a crown portion. 4, except that the pneumatic tire of Example 1 is not provided.

The pneumatic tires of Examples 1 to 3 according to the present invention, the pneumatic tire of the conventional example, and the pneumatic tire of the comparative example were subjected to comparative tests of the steering stability performance and vibration riding comfort performance of the tires. . The exam is
The test tire was mounted on a 2500 cc class passenger car, and evaluated by the feeling of a test driver.

When the steering stability performance and the vibration riding comfort performance of the conventional pneumatic tire described above are represented by a ± 5 point method when ± 0, the steering stability performance and the vibration riding comfort of the pneumatic tire of the first embodiment are shown. Performance was +4 and +1 respectively.

When the steering stability performance and the vibration riding comfort performance of the conventional pneumatic tire described above are represented by a ± 5 point method when ± 0, the steering stability performance and the vibration riding comfort of the pneumatic tire of the second embodiment are shown. Performance was +2 and +3, respectively.

When the steering stability performance and the vibration riding comfort performance of the conventional pneumatic tire are expressed by ± 5 points when ± 0, the steering stability performance and the vibration riding comfort of the pneumatic tire of the third embodiment are shown. Performance was +3 and +2, respectively.

When the steering stability performance and the vibration riding comfort performance of the above-described conventional example are represented by the ± 5 point method when ± 0, the steering stability performance and the vibration riding comfort performance of the comparative example are shown. Was +3 and -4, respectively.

Table 1 summarizes the results of the comparative test of the steering stability performance and the vibration riding comfort performance together with the outline of the test tires.

[0019]

[Table 1]

[0020]

From the above evaluation results, it can be seen that the pneumatic tire of the embodiment based on the present invention has extremely excellent steering stability performance and vibration riding comfort performance as compared with the conventional pneumatic tire. .

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of the left half of a pneumatic tire according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bead core 2 Radial carcass 3 Belt 4 Carcass auxiliary layer 5 Belt reinforcement layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B60C 9/20 B60C 9/20 EF

Claims (4)

[Claims] 1. A bead core provided in a pair of left and right bead portions, a carcass wound around the bead core and moored in the left and right bead portions, and a carcass portion disposed radially outward of a crown portion of the carcass. (1) The carcass is formed by embedding a large number of metal cords arranged in parallel and in a radial direction in rubber in rubber and passing through both side portions from right and left bead portions. The belt is formed of a pair of right and left radial cord layers extending at least to both ends of the crown and terminating without exceeding the center of the crown. (2) The belt has a cord direction of about 10 to 30 degrees with respect to the circumferential direction of the tire. At an angle, at least two layers are arranged parallel to each other within the layers, and are stacked in opposite directions with respect to the tire equator between the layers,
It is formed by a layer consisting of a large number of metal cords embedded in rubber,
(3) A single carcass auxiliary layer extending continuously from one bead portion to the other bead portion is disposed adjacent to the carcass, and the carcass auxiliary layers are arranged in a large number in parallel with each other and in a radial direction. Pneumatic radial for passenger cars, characterized in that the organic fiber cord is embedded in rubber.
tire. 2. The pneumatic radial tire for a passenger car according to claim 1, wherein the carcass auxiliary layer is disposed adjacent to the carcass inside the tire. 3. The method according to claim 1, wherein a distance between one end portion and the other end portion of the crown portion of the pair of left and right radial cord layers forming the carcass is 5 to 70% of a cross-sectional width of the belt. The pneumatic radial tire for a passenger car according to claim 1 or 2, wherein: 4. The pneumatic radial tire for a passenger car according to claim 1, wherein the carcass is formed of a radial cord layer formed by embedding a metal cord having a single twist structure in rubber. .