JPH075811U - Pneumatic tire - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention relates to a pneumatic tire having excellent ride comfort and straight running stability at high speed. The pneumatic tire 1 according to the present invention includes a toroidal carcass 2 formed of at least one ply of cords arranged substantially in a radial arrangement. A belt 5 composed of at least two rubberized layers arranged in a cross cord arrangement of small angles, and a belt reinforcing layer 6 composed of at least one rubberized layer of organic fiber cords arranged substantially parallel to the plane 4. The belt 5 and the tread portion 7 reinforced by the belt reinforcing layer 6 are provided, and the tread portion 7 has a thin insert rubber 8 which is narrow and relatively hard inside the central portion thereof.
It is characterized by having.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a pneumatic tire having excellent ride comfort and straight running stability at high speeds.

[0002]

[Prior art]

 As vehicles become more sophisticated, demands for improved comfortability such as noise and riding comfort are increasing, and further improvement in steering stability, especially in straight-ahead driving stability at high speeds, is desired. In order to improve riding comfort, a tire structure is designed so that when the tire rolls on a bumpy road surface and receives a shock, the tire itself absorbs this shock and does not transmit it to the vehicle. Well, for that reason, it is known that the rigidity of the tire itself should be reduced.

[0003]

[Problems to be solved by the device]

 However, if the rigidity of the tire itself is reduced, straight-line stability at high speeds will be reduced, and the vehicle will fluctuate while driving, making the driver feel uneasy and extremely dangerous. As described above, the riding comfort and the straight running stability are generally in a conflicting relationship, and it is difficult to satisfy both.

Therefore, an object of the present invention is to complete a pneumatic tire which is excellent in riding comfort and is also excellent in straight running stability at high speed running.

[0005]

[Means for Solving the Problems]

 The present invention provides at least two cross cord arrangements having a comparatively small angle with respect to a plane including the tread circumference, outside the crown portion of a toroidal carcass consisting of at least one ply of cords arranged in a substantially radial arrangement. Belt made of a rubberized layer, a belt reinforcement layer made of at least one rubberized layer of organic fiber cords arranged substantially parallel to the plane, and a tread portion reinforced by these belts and belt reinforcement layers. In the pneumatic tire including, the tread portion is provided with a thin insert rubber that is narrow and relatively hard inside the central portion of the tread portion.

An example of a typical cross section in the width direction of the pneumatic tire of the present invention is shown in FIG. 1, in which 1 is a pneumatic tire, 2 is a carcass, 3 is a crown portion, 4 is a plane including a tread circumference, Reference numeral 5 is a belt, 6 is a belt reinforcing layer, 7 is a tread portion, and 8 is insert rubber. The pneumatic tire 1 shown in FIG. 1 has a toroidal carcass 2 consisting of a single ply of cords arranged substantially in a radial arrangement, outside the crown portion 3 thereof, and at a relatively small angle with respect to a plane 4 including the tread circumference. A belt 5 composed of two rubberized layers arranged in a cross cord arrangement, and a belt reinforcement layer 6 composed of a single rubberized layer of organic fiber cords arranged substantially parallel to the plane, and these belts 5 And a tread portion 7 strengthened by the belt reinforcing layer 6, and the tread portion 7 is provided with a thin insert rubber 8 having a narrow width and relatively hardness inside the central portion thereof.

The hardness of the insert rubber 8 is preferably larger than the hardness of the portion of the tread portion 7 surrounding the insert rubber 8, and particularly, the rubber hardness of the insert rubber 8 is 2 times greater than that of the tread portion 7. It is more preferable to increase only the range of -10 °. If it is less than 2 °, the straight running stability cannot be sufficiently enhanced, and if it exceeds 10 °, the tire rigidity is too high and the riding comfort is deteriorated. The rubber hardness was measured by a Shore A hardness tester according to JIS K6301. The thickness of the insert rubber 8 is preferably in the range of 1.0 to 3.0 mm. If it is less than 1.0 mm, it is not possible to sufficiently reinforce the rigidity of the tread portion in the center of the tire width direction, and if it exceeds 3.0 mm, on the contrary, the rigidity of the tread portion in the center of the tire width direction becomes too large and the riding comfort is increased. This is because it deteriorates sex. The width of the insert rubber 8 is set within the range of 85% or less of the belt width with respect to the plane including the tread center circumference, so that the straight running stability at high speed traveling is not deteriorated without reducing the riding comfort. It is preferable to increase the height, and more preferably 70% or less of the belt width.

[0008]

[Action]

 The present invention includes an insert rubber 8 having a width narrower than that of the tread portion 7 between the belt 5 and the tread portion 7. The insert rubber 8 has a thickness in the range of 1.0 to 3.0 mm. By increasing the rubber hardness to be higher than the rubber hardness of the tread portion, it is possible to increase only the rigidity of the central portion of the tread portion while hardly changing the rigidity of the side portions of the tire.

[0009]

【Example】

 A specific embodiment of the pneumatic tire according to the present invention will be described with reference to FIG. In Example 1, the tire size was 205 / 60R15, and the tread was placed outside the crown portion 3 of the toroidal carcass 2 consisting of one ply of rayon cords arranged at 90 ° with respect to the plane 4 including the tread circumference. A belt 5 composed of two layers of rubberized layers arranged in a cross cord arrangement at an angle of 20 ° with respect to a plane 4 including a circumference, and a rubber layer of an organic fiber cord arranged at an angle of 0 ° with respect to the plane The belt reinforcing layer 6 made of a pulling layer and the belt 5 and the tread portion 7 reinforced by the belt reinforcing layer 6 are provided, and the belt reinforcing layer 6 and the tread portion 7 have a narrower width than the tread portion 7. The insert rubber 8 is provided. The thickness of the insert rubber 8 was 1.5 mm, and the rubber hardness of the insert rubber 8 was 67 °. The rubber hardness of the insert rubber 8 was made larger by 2 ° than the rubber hardness (65 °) of the tread portion 7. The width of the insert rubber 8 was set to 85% of the belt width centering on the plane including the tread central circumference.

As the cord 2 of the carcass 2, a rayon cord was used. Belt 5 is made of two rubberized layers, the code of the rubberized layer, using a steel Lumpur code, the disposed angle of the cord with respect to the plane 4 was 22 °. A nylon cord was used as the cord of the belt reinforcing layer 6, and the belt reinforcing layer 6 was composed of one cap layer and one layer layer. This tire was tested.

Example 2 is a tire having substantially the same structure as the tire used in Example 1 except that the rubber hardness of the insert rubber 8 was 70, and this tire was subjected to the test. Example 3 is a tire having substantially the same structure as the tire used in Example 1 except that the rubber hardness of the insert rubber 8 is 70 and the width of the insert rubber 8 is 65% of the belt width. Yes, this tire was tested. The comparative example is a conventional tire that does not require modification except that the rubber hardness of the insert rubber is 65 °, which is the same as that of the tread rubber, and this tire was subjected to the test.

The test was carried out by evaluating the feeling of the driver in the actual vehicle running with respect to the high-speed maneuverability and the riding comfort, and the feeling was evaluated in 10 steps. Table 1 shows the test results. The larger the numerical value in the table, the better.

[0013]

[Table 1]

From the results in Table 1, Example 1 has the same riding comfort and excellent high-speed maneuverability as compared with the comparative example. The example 2 is somewhat inferior to the comparative example in riding comfort, but is particularly excellent in high-speed steering performance. Compared to the comparative example, the example 3 has the same riding comfort and excellent high-speed steering performance, and is the most excellent in the comprehensive evaluation.

[0015]

[Effect of device]

 The present invention includes an insert rubber 8 having a width narrower than that of the tread portion 7 between the belt 5 and the tread portion 7. The insert rubber 8 has a thickness in the range of 1.0 to 3.0 mm. By making the rubber hardness higher than the rubber hardness of the tread portion 7, it is possible to increase only the rigidity of the central portion of the tread portion while hardly changing the rigidity of the side portion of the tire. Therefore, even if the tire rolls under load and receives an impact due to unevenness of the road surface, it can be deformed sufficiently from the shoulder portion to the sidewall portion to absorb the impact, and good ride comfort can be secured. In addition, the straight running stability is improved by the increase in the rigidity of the central part of the tread.

[Brief description of drawings]

FIG. 1 is a perspective view of a widthwise half cross section of a device tire used in Example 1. FIG.

[Explanation of symbols]

 1 Pneumatic tire 2 Carcass 3 Crown 4 Flat surface including tread circumference 5 Belt 6 Belt reinforcement layer 7 Tread 8 Insert rubber

Claims (1)

[Scope of utility model registration request] 1. A toroidal carcass consisting of at least one ply of cords arranged in a substantially radial arrangement, and at least two cords outside the crown portion of the toroidal carcass, which form a cross cord arrangement having a relatively small angle with respect to a plane including the tread circumference. A belt made of a rubberized layer, a belt reinforcing layer made of at least one rubberized layer of organic fiber cords arranged substantially parallel to the plane, and a tread portion reinforced by the belt and the belt reinforcing layer. A pneumatic tire provided with a tread portion having a thin insert rubber that is narrow and relatively hard inside a central portion thereof.