JP2016068904A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire that can effectively improve steering stability.SOLUTION: The pneumatic tire has a belt constituted of two or more belt layers. The belt includes a crossing belt constituted by laying two crossing belt layers on each other, made of rubber-coated layers of multiple parallely arranged belt cords that cross with each other between the layers. Difference between inclination angles of the belt cords of the inner crossing belt layer inside in a tire radial direction of the crossing belt relative to a tire circumference direction and inclination angles of the belt cords of the outer crossing belt layer outside in a tire radial direction of the crossing belt relative to the tire circumference direction are 0 to 30°, and rigidity of the outer crossing belt layer is 1.35 to 1.8 times rigidity of the inner crossing belt layer.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  Conventionally, in a pneumatic tire, in order to improve steering stability at the time of running, the rigidity of a tire constituent member is raised. Specifically, increasing the rigidity of the tread portion, sidewall portion, belt, and the like of the pneumatic tire is effective in improving the steering stability.

  Among the tire constituent members, the belt is usually composed of one or more belt layers made of a rubberized layer of a belt cord (for example, a steel cord). Therefore, the rigidity of the belt greatly depends on the arrangement and rigidity of the belt cord and the rigidity of the coating rubber. That is, in order to improve the rigidity of the belt, it is effective to densely arrange the belt cords having high rigidity and use the coating rubber having high rigidity. According to such a technique, the rigidity in the tire circumferential direction and the tire width direction of the pneumatic tire can be secured, and the steering stability can be improved.

  As a technique as described above, for example, in Patent Document 1, in an intersecting belt composed of two intersecting belt layers, the cord diameter of the intersecting belt layer on the outer side in the tire radial direction and the number of belt cords to be driven are There has been proposed a technique for improving the handling stability by increasing the crossing belt layer contrast.

JP 2009-083522 A

  However, the technique described in Patent Document 1 has a problem in that the weight of the tire is increased because the cord diameter and the number of cords to be driven are increased. There was a problem that the effect of improving the belt rigidity was low. Such a problem of weight increase is remarkable when a steel cord is used with high rigidity.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a pneumatic tire that can effectively improve steering stability.

The gist configuration of the present invention is as follows.
The pneumatic tire of the present invention has a belt composed of two or more belt layers, and the belt is formed by stacking two intersecting belt layers composed of rubberized layers of a plurality of parallel belt cords that intersect each other. An inclination angle of the inner cord belt layer positioned on the inner side in the tire radial direction of the cross belt with respect to the tire circumferential direction of the belt cord, and an outer cross belt layer positioned on the outer side in the tire radial direction of the cross belt. The difference between the inclination angle of the belt cord with respect to the tire circumferential direction is 0 to 30 °, and the rigidity of the outer intersection belt layer is 1.35 to 1.8 times the rigidity of the inner intersection belt layer. It is characterized by.
According to the pneumatic tire of the present invention, steering stability can be effectively improved.

  Here, “rigidity” of “inner crossing belt layer” and “outer crossing belt layer” means the Young's modulus of the belt cord constituting the crossing belt layer and the unit width of the crossing belt layer (extension of the belt cord) Multiplied by the number of driving belt cords per unit width (hereinafter simply referred to as the number of driving), and the Young's modulus of the belt cord is the belt cord cut out from the product tire. The test is conducted according to JIS L1017 8.5 a) (2002) and obtained in accordance with JIS L1017 8.8 (2002).

In the pneumatic tire of the present invention, the inclination angle of the outer cross belt layer with respect to the tire circumferential direction of the belt cord is smaller than the inclination angle of the inner cord belt layer with respect to the tire circumferential direction of the belt cord. Is preferred.
According to this configuration, steering stability can be further improved.

Furthermore, in the pneumatic tire of the present invention, it is preferable that the number of driving of the belt cords of the outer crossing belt layer is smaller than the number of driving of the belt cords of the inner crossing belt layer.
Here, “the number of driving” of “belt cord” of “outer crossing belt layer” and “inner crossing belt layer” means the unit width of the crossing belt layer (as viewed in the direction perpendicular to the belt cord extending direction). The number of belt cords driven per width).
According to this configuration, the steering stability can be further improved.

Furthermore, in the pneumatic tire of the present invention, it is preferable that the crossing belt is composed of two layers of the crossing belt layers.
According to this configuration, the tire weight can be sufficiently reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which can improve steering stability effectively can be provided.

It is a figure which shows typically the belt structure of the pneumatic tire of one Embodiment of this invention. It is a figure which shows the relationship between the inclination angle difference of a belt cord, the rigidity ratio of a crossing belt layer, and steering stability.

  Hereinafter, embodiments of the pneumatic tire of the present invention (hereinafter also simply referred to as a tire) will be described in detail as examples.

  FIG. 1 is a diagram schematically showing a belt structure of a pneumatic tire according to an embodiment of the present invention. The pneumatic tire of the present embodiment has a belt composed of two or more belt layers. As shown in FIG. 1, the belt is rubberized by a large number of parallel belt cords C1 and C2 that cross each other. The crossing belt 3 is formed by stacking two layers of crossing belt layers (outer crossing belt layer 1 and inner crossing belt layer 2).

  In the present invention, the internal structure of the tire other than the belt structure is the same as that of the conventional structure. For example, the cross belt 3 and the tread described above are disposed radially outward of the carcass straddling a pair of bead portions in a toroidal shape. In order. Further, in the present invention, the belt structure is not limited to the example shown in FIG. 1. For example, a belt reinforcement composed of one or more belt reinforcement layers on the outer side and / or the inner side of the crossing belt layer 3 in the tire radial direction. It can also have a layer.

  Here, as a result of intensive studies by the inventor to solve the above problems, the rigidity E1 of the outer crossing belt layer 1 positioned on the outer side in the tire radial direction of the crossing belt 3 is changed to the inner side in the tire radial direction of the crossing belt 3. Although it is effective for improving the steering stability to increase the rigidity E2 of the inner crossing belt layer 2 located at the position 2, if the ratio is too large, the crossing belt 3 is twisted and deformed (crossing belt 3) when traveling. However, it has been found that the steering stability tends to decrease due to the occurrence of a deformation that undulates with the tire radial direction as the amplitude direction.

Further, the inventor of the present invention has a case where the difference between the inclination angle θ2 of the inner cord belt 2 with respect to the tire circumferential direction of the belt cord C2 and the inclination angle θ1 of the outer cord belt 1 with respect to the tire circumferential direction of the belt cord C1 is too large. In addition, it has been found that twisting deformation occurs in the cross belt 3 and steering stability tends to be lowered.
Then, the inventor, as will be described in detail in the examples described later, has a rigidity ratio E1 / E2 between the outer crossing belt layer 1 and the inner crossing belt layer 2, and tires of belt cords C1 and C2 constituting these. The present invention was completed by obtaining new knowledge that it is extremely effective to improve the steering stability by regulating the inclination angle difference | θ2−θ1 | with respect to the circumferential direction under a predetermined condition.

In the pneumatic tire of this embodiment, the difference between the inclination angle θ2 of the belt cord C2 of the inner crossing belt layer 2 with respect to the tire circumferential direction and the inclination angle θ1 of the belt cord C1 of the outer crossing belt layer 1 with respect to the tire circumferential direction | θ2 −θ1 | is 0 to 30 °, and the rigidity E1 of the outer crossing belt layer 1 is 1.35 to 1.8 times the rigidity E2 of the inner crossing belt layer 2.
According to the present embodiment, by setting the ratio E1 / E2 to 1.35 times or more, the rigidity E1 of the outer crossing belt layer 1 that greatly contributes to the handling stability is increased in comparison with the rigidity E2 of the inner crossing belt layer 2. On the other hand, when the ratio E1 / E2 is 1.8 or less and | θ2−θ1 | is 30 ° or less, the torsional deformation of the cross belt 3 can be suppressed. Therefore, according to the present embodiment, the steering stability can be improved.
On the other hand, since the ratio E1 / E2 is 1.8 or less, the rigidity E1 of the outer crossing belt layer 1 is not excessively increased in comparison with the rigidity E2 of the inner crossing belt layer 2, and therefore the ratio E1 / E2 is set to 1. For example, the cord diameter of the belt cord C1 is not increased more than necessary, or the number of driving of the belt cord C1 is not increased more than necessary as compared with the case of exceeding .8.
As described above, according to the pneumatic tire of the present embodiment, steering stability can be effectively improved.

Here, in the pneumatic tire of the present invention, in particular, the inclination angle difference | θ2−θ1 | is preferably 8 ° to 20 °, and the rigidity ratio E1 / E2 is 1.35 to 1.2. 69 is preferred. This is because the steering stability can be further improved by setting the above numerical range. Note that it is preferable not to set | θ2−θ1 | to be 0 ° but to have a substantial difference in inclination angle because the roles of the outer crossing belt layer 1 and the inner crossing belt layer 2 are more clearly defined. This is because the rigidity in each of the direction and the tire width direction (and thus the handling stability) can be improved more appropriately, and the handling stability can be improved comprehensively. For the same reason, in the pneumatic tire of the present invention, the inclination angle difference | θ2−θ1 | is 8 ° to 20 °, and the stiffness ratio E1 / E2 is 1.35 to 1.69. Further preferred.
The angle θ1 is preferably 20 to 30 °, and the angle θ2 is preferably 30 to 45 °.

  The rigidity E1 of the outer crossing belt layer 1 and the rigidity E2 of the inner crossing belt layer 2 are adjusted by adjusting the material and the cord diameter of the belt cords C1 and C2, the twisted structure, the number of driving of the belt cords C1 and C2, and the like. It can be adjusted to the above range. The material of the belt cords C1 and C2 is not particularly limited, but a steel cord is preferably used, and an organic fiber cord or the like can also be used.

In the pneumatic tire of the present invention, the inclination angle of the belt cord C1 of the outer cross belt layer 1 with respect to the tire circumferential direction is preferably smaller than the inclination angle of the belt cord C2 of the inner cross belt layer 2 with respect to the tire circumferential direction.
Since the crossing belt layer on the outer side in the tire radial direction has a larger contribution to improving the rigidity in the tire circumferential direction, the steering stability can be improved by reducing the inclination angle of the belt cord C1 of the outer crossing belt layer 1 with respect to the tire circumferential direction. It is because it can improve effectively.

Furthermore, in the pneumatic tire of the present invention, the number n1 of driving of the belt cord C1 of the outer crossing belt layer 1 is preferably smaller than the number of driving n2 of the belt cord C2 of the inner crossing belt layer 2.
This is because the grounding property can be secured and the steering stability can be further improved.

  Furthermore, in the pneumatic tire of the present invention, as in the embodiment shown in FIG. 1, the cross belt 3 is composed of only two cross belt layers, that is, the belt is a double cross belt as a belt layer. Preferably it contains only layers. This is because the tire weight can be kept sufficiently small.

  Two or more pneumatic radial tires for passenger cars with tire size 225 / 45R17 having a cross belt composed of two cross belt layers, with various changes in the belt cord cord structure, the number of drivings, and the inclination angle with respect to the tire circumferential direction. The steering stability of each tire was evaluated as follows. The specifications of each tire are shown in Table 1. The “belt stiffness” in the table is a value obtained by measuring the tire circumferential direction stiffness and the tire width direction stiffness of the crossing belt and taking the average. The tire circumferential direction rigidity of the crossing belt is a unit crossing belt having a unit width in the tire width direction, a unit length in the tire circumferential direction, and a thickness including two crossing belt layers from the crossing belt of the test tire. In order to generate a certain strain in the direction corresponding to the tire circumferential direction in the cut unit intersection belt when the tension in the direction corresponding to the tire circumferential direction is applied to the cut unit intersection belt. The tension required for Similarly, in the tire width direction rigidity of the crossing belt, when the unit crossing belt is cut out, and when the tension in the direction corresponding to the tire width direction is applied to the cut out unit crossing belt, The tension required to generate a certain strain in the direction corresponding to the tire width direction.

<Steering stability>
The tire was mounted on a vehicle and the steering stability during cornering when the vehicle was running was evaluated based on the sensitivity of the driver. The tire evaluation result according to Comparative Example 1 below was expressed as an index, which was taken as 100. Is. In addition, it shows that it is excellent in steering stability, so that a numerical value is large.
Tables 1 and 2 below and FIG. 2 show the specifications and evaluation results of each tire.
Table 2 shows an evaluation result of steering stability by excerpting a part of Table 1. Data of the inclination angle difference θ2−θ1 = 0 ° and the rigidity ratio E1 / E2 = 1 are as follows: Of Comparative Examples 1 and 2 in Table 1, Comparative Example 1 is used. The data of θ2−θ1 = 0 ° and the rigidity ratio E1 / E2 = 1.35 are those of Invention Example 1 among Invention Examples 1 and 8 in Table 1. FIG. 2 corresponds to Table 2.

  As shown in Table 1, Table 2, and FIG. 2, it was found that the steering stability is improved when the inclination angle difference | θ2−θ1 | and the rigidity ratio E1 / E2 are both within a predetermined range. . Specifically, as shown in Table 1, Table 2, and FIG. 2, the inclination angle difference | θ2-θ1 | is 0 to 30 °, and the rigidity ratio E1 / E2 is 1.35 to 1.8. In case, the handling stability was improved.

  Further, as shown in Table 1, Table 2, and FIG. 2, particularly when the inclination angle difference | θ2-θ1 | is 8 to 20 °, the steering stability is further improved, or the ratio E1 / E2 It can be seen that the steering stability is further improved when is 1.35 to 1.69. It can be seen that when | θ2−θ1 | is 8 to 20 ° and the ratio E1 / E2 is 1.35 to 1.69, the effect of improving the steering stability is particularly high.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which improved the steering stability effectively can be provided. The pneumatic tire according to the present invention is particularly preferably used for a pneumatic radial tire for passenger cars.

1 outer cross belt layer 2 inner cross belt layer 3 cross belt C1, C2 belt cord

Claims (4)

A belt comprising two or more belt layers, the belt comprising a cross belt comprising two cross belt layers made of rubberized layers of a plurality of parallel belt cords crossing each other between layers; Tire,
The inclination angle of the inner cord belt layer located on the inner side in the tire radial direction of the cross belt with respect to the tire circumferential direction of the belt cord, and the tire circumference of the belt cord on the outer cross belt layer located on the outer side in the tire radial direction of the cross belt The difference from the tilt angle with respect to the direction is 0-30 °,
The pneumatic tire according to claim 1, wherein a rigidity of the outer cross belt layer is 1.35 to 1.8 times that of the inner cross belt layer.   The pneumatic tire according to claim 1, wherein an inclination angle of the outer cross belt layer with respect to a tire circumferential direction of the belt cord is smaller than an inclination angle of the inner cross belt layer with respect to a tire circumferential direction of the belt cord.   The pneumatic tire according to claim 1 or 2, wherein the number of driving of the belt cords of the outer crossing belt layer is smaller than the number of driving of the belt cords of the inner crossing belt layer.   The pneumatic tire according to any one of claims 1 to 3, wherein the belt is composed of only two layers of the intersecting belt layers.

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