JP6568790B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that can improve high-speed durability and separation resistance without impairing uniformity.

  As disclosed in Patent Document 1, a pneumatic tire including a pair of reinforcing layers covering end portions of a belt layer is known. According to this configuration, it is possible to prevent the end of the belt layer from rising when traveling at a high speed and to improve high-speed durability. On the other hand, when traveling at a normal speed, the distortion caused by the deformation of the tire repeatedly acts on the end of the belt layer, so there is a concern about separation between members starting from the end of the belt layer. Therefore, it is desired to improve the separation resistance as well as the high speed durability, but it is not sufficient to provide the reinforcing layer as described above.

  In order to achieve both high speed durability and separation resistance, the present inventor has provided a pair of reinforcing layers covering the end of the belt layer, and disposed a rubber pad under the end of the belt layer, It was considered to reduce the distortion generated in the part. However, since the end portion of the belt layer is firmly restrained by the reinforcing layer, it has been found that the rubber pad is deformed and escapes from below the end portion of the belt layer, and the separation resistance may not be sufficiently improved. Further, depending on the mode of the pair of reinforcing layers, the uniformity of the tire may be deteriorated.

  Patent Documents 1 to 4 each describe a pneumatic tire provided with a reinforcing layer that covers the end of the belt layer, but it does not suggest a solution to the problem related to the rubber pad as described above. Absent.

JP-A-6-24208 JP 2014-213802 A JP 2014-37217 A JP 2001-310605 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a pneumatic tire that can improve high-speed durability and separation resistance without impairing uniformity.

  The above object can be achieved by the present invention as described below. That is, a pneumatic tire according to the present invention is provided on a carcass layer provided between a pair of bead portions, a first belt ply provided on an outer periphery of the carcass layer, and an outer periphery of the first belt ply. A belt layer including a second belt ply, a pair of fiber reinforcement layers covering both end portions of the first and second belt plies, and an end portion of the first belt ply and the carcass layer. A pair of rubber pads, each of the first and second belt plies includes a belt cord extending in a direction inclined with respect to the tire circumferential direction, and the fiber reinforcement layer is inclined with respect to the tire circumferential direction. Of the pair of fiber reinforcement layers, and the inclination direction of the organic fiber cord included in one and the inclination direction of the organic fiber cord included in the other are opposite to each other. And both the organic fiber cords extend in a direction intersecting the belt cord of the first belt ply, the inclination angle θb of the belt cord of the first belt ply with respect to the tire circumferential direction, and the fiber reinforcing layer The inclination angle θs of the organic fiber cord with respect to the tire circumferential direction satisfies the relationship of 0.8θb ≦ θs ≦ 0.95θb or 1.05θb ≦ θs ≦ 1.20θb.

  In this tire, high-speed durability can be improved by providing a pair of fiber reinforcement layers covering both ends of the first and second belt plies. Moreover, since the fiber reinforcing layer includes an organic fiber cord extending in a direction inclined with respect to the tire circumferential direction, the binding force is not excessively increased, and the thickness of the rubber pad below the end of the belt layer is ensured to prevent separation. Can be improved. The extension of the organic fiber cord of the fiber reinforcing layer in the direction intersecting with the belt cord of the first belt ply is useful for appropriately generating the restraining force. Moreover, since the inclination directions of the organic fiber cords included in the pair of fiber reinforcement layers are opposite to each other, the fiber reinforcement layers are arranged symmetrically, and deterioration of uniformity is suppressed.

  Further, in this tire, the inclination angle θb and the inclination angle θs satisfy the relationship of 0.8θb ≦ θs ≦ 0.95θb or 1.05θb ≦ θs ≦ 1.20θb. Thus, since the relationship of θs ≦ 0.95θb or 1.05θb ≦ θs is satisfied, the deviation between the belt cord and the organic fiber cord is appropriately ensured, and as a result, the restraining force is exerted while the organic fiber cord is inclined. It can be generated appropriately. Nevertheless, since the relationship of 0.8θb ≦ θs ≦ 1.20θb is satisfied, the deviation between the belt cord and the organic fiber cord does not become too large, and as a result, the occurrence of the so-called tag effect is suppressed and the binding force increases. Can be prevented.

  It is preferable that the end of the fiber reinforcement layer on the outer side in the tire width direction is disposed on the outer side in the tire width direction of the end of the rubber pad located on the inner peripheral side of the fiber reinforcement layer in the tire width direction. According to such a configuration, the deformation of the rubber pad that escapes outward in the tire width direction is prevented, the thickness of the rubber pad under the end of the belt layer is secured, and the separation resistance can be improved more favorably.

  It is preferable that an end portion of the fiber reinforcing layer on the inner side in the tire width direction is disposed on the inner side in the tire width direction of an end portion on the inner side of the rubber pad in the tire width direction. According to such a configuration, the thickness of the rubber pad under the end of the belt layer can be secured and the separation resistance can be improved more favorably.

Tire meridian cross-sectional view showing an example of a pneumatic tire according to the present invention Sectional drawing which expands and shows the principal part of the pneumatic tire of FIG. Plan view showing belt layer, fiber reinforcement layer and rubber pad

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, a pneumatic tire for a light truck is illustrated, but the present invention is not limited to this.

  A pneumatic tire T shown in FIGS. 1 and 2 includes a pair of bead portions 1, a sidewall portion 2 extending outward in the tire radial direction from each of the bead portions 1, and an outer side in the tire radial direction of each of the sidewall portions 2. And a tread portion 3 connected to the end. The bead portion 1 is provided with an annular bead core 1a formed by rubber-covering a converging body such as a steel wire, and a bead filler 1b disposed on the outer side in the tire radial direction of the bead core 1a. Although not shown, a tread pattern is formed on the outer periphery of the tread portion 3 in accordance with required tire performance and use conditions.

  The tire T further includes a carcass layer 4 provided between the pair of bead portions 1, a belt layer 5 provided on the outer periphery of the carcass layer 4 in the tread portion 3, and an end portion of the belt layer 5. A pair of disposed fiber reinforcement layers 6 and a pair of rubber pads 7 disposed below the end of the belt layer 5 are provided. The carcass layer 4 has a toroidal shape as a whole, and is wound up with its end portions sandwiching the bead core 1a and the bead filler 1b. The carcass layer 4 is configured by a carcass ply including a carcass cord extending in a direction substantially orthogonal to the tire circumferential direction. In the present embodiment, there is one carcass ply, but two or more may be used.

  The belt layer 5 includes a belt ply 51 (first belt ply) provided on the outer periphery of the carcass layer 4 and a belt ply 52 (second belt ply) provided on the outer periphery of the belt ply 51. 51 is formed wider than the belt ply 52. As shown in FIG. 3, each belt ply 51, 52 includes a belt cord C5 extending in a direction inclined with respect to the tire circumferential direction so that the belt cord C5 crosses in opposite directions between the plies. Has been placed. The inclination angle θb of the belt cord 51 with respect to the tire circumferential direction of the belt ply 51 is, for example, 18 to 24 degrees, and the belt ply 52 is the same as this.

  The pair of fiber reinforcement layers 6 cover both ends of the belt ply 51 and the belt ply 52. As a result, it is possible to prevent the end of the belt layer 5 from rising at a high speed and to improve the high speed durability. The pair of fiber reinforcement layers 6 each include an organic fiber cord C6 extending in a direction inclined with respect to the tire circumferential direction. In order to prevent the restraining force due to the fiber reinforcing layer 6 from increasing, the inclination angle θs of the organic fiber cord C6 with respect to the tire circumferential direction is preferably 5 degrees or more. Examples of the material of the organic fiber cord C6 include nylon, rayon, polyester, and aramid.

  In the tire T, as shown in FIG. 3, the inclination direction of the organic fiber cord C <b> 6 included in one (for example, the left fiber reinforcement layer 6) and the other (for example, the right fiber reinforcement layer) of the pair of fiber reinforcement layers 6. The inclination directions of the organic fiber cords C6 included in 6) are opposite to each other. That is, the organic fiber cords C6 included in the pair of fiber reinforcement layers 6 are arranged in directions that are symmetric with respect to the tire circumferential direction. Thereby, the fiber reinforcement layer 6 which makes a pair is arrange | positioned symmetrically, and the deterioration of uniformity is suppressed.

  The pair of rubber pads 7 are interposed between the end portion of the belt ply 51 and the carcass layer 4 and are annularly arranged along the tire circumferential direction. The rubber pad 7 is formed of a rubber body that does not contain a cord (that is, does not contain a cord). By providing the rubber pad 7, it is possible to reduce the distortion generated at the end of the belt layer 5 (mainly the end of the belt ply 51), and to suppress the separation between the members starting from the end.

  The rubber pad 7 of the present embodiment has a cross-sectional shape in which the thickness gradually decreases toward both end portions thereof. In order to improve the separation resistance, it is necessary to secure the thickness of the rubber pad 7 below the end of the belt layer 5, specifically, the thickness T7 measured from the end 51E of the belt ply 51 toward the inner side in the tire radial direction. Become important. However, when the end portion of the belt layer 5 is firmly constrained, the rubber pad 7 is deformed and escapes from below the end portion of the belt layer 5, and the separation resistance is deteriorated because the thickness T7 is not sufficiently secured. There is a fear.

  However, in this pneumatic tire T, since the fiber reinforcing layer 6 includes the organic fiber cord C6 extending in the direction inclined with respect to the tire circumferential direction, the binding force does not become too large, and the end of the belt layer 5 Separation resistance can be improved by securing the thickness T7 of the rubber pad 7 under the subordinate. Nevertheless, since the organic fiber cords C6 of both of the pair of fiber reinforcement layers 6 extend in the direction intersecting the belt cord C5 of the belt ply 51, a restraining force can be generated appropriately. The thickness T7 is preferably 2 mm or more, and more preferably 3 mm or more.

  As shown in FIGS. 1 and 2, the end of the fiber reinforcing layer 6 on the outer side in the tire width direction is more in the tire width direction than the end of the rubber pad 7 located on the inner peripheral side of the fiber reinforcing layer 6 on the outer side in the tire width direction. Arranged outside. Thereby, the deformation of the rubber pad 7 that escapes to the outside in the tire width direction is prevented, the thickness T7 is secured, and the separation resistance can be improved more favorably. Further, the end of the fiber reinforcing layer 6 on the inner side in the tire width direction is disposed on the inner side in the tire width direction of the end of the rubber pad 7 located on the inner peripheral side of the fiber reinforcing layer 6 on the inner side in the tire width direction. In addition, the thickness T7 of the rubber pad 7 can be secured to improve the separation resistance more favorably.

  In the present embodiment, the fiber reinforcement layer 6 is formed wider than the rubber pad 7, and the rubber pad 7 is completely covered with the fiber reinforcement layer 6. The lengths L6o and L6i from the end 51E of the belt ply 51 to both ends of the fiber reinforcement layer 6 are preferably not more than 3 times the distance D. Thereby, the fiber reinforcement layer 6 does not become larger than necessary, and waste in terms of tire weight and cost can be prevented. On the other hand, in order to ensure the thickness T7 of the rubber pad 7, the lengths L7o and L7i from the end 51E of the belt ply 51 to both ends of the rubber pad 7 are preferably equal to or greater than the distance D, respectively. . The distance D is a distance from the end 51E of the belt ply 51 to the end 52E of the belt ply 52.

  The lengths L6o and L6i, the lengths L7o and L7i, and the distance D are dimensions measured along the tire width direction. The dimensions of each part of the tire including these and inclination angles θb, θs described later are measured in a no-load state in which the tire is mounted on a regular rim and filled with a regular internal pressure.

  As described above, the organic fiber cord C6 extends in a direction crossing the belt cord C5, and the inclination angle θb of the belt cord C5 with respect to the tire circumferential direction and the inclination angle θs of the organic fiber cord C6 with respect to the tire circumferential direction are Different from each other. The inclination angle θb and the inclination angle θs are set so as to satisfy the relationship of 0.8θb ≦ θs ≦ 0.95θb or 1.05θb ≦ θs ≦ 1.20θb. Thereby, since the relationship of θs ≦ 0.95θb or 1.05θb ≦ θs is satisfied, the angular difference between them is set to 5% or more of the inclination angle θb, and the deviation between the belt cord C5 and the organic fiber cord C6 is moderate. Secured. As a result, the restraining force can be appropriately generated while the organic fiber cord C6 is inclined.

  Further, since the inclination angle θb and the inclination angle θs satisfy the relationship of 0.8θb ≦ θs ≦ 1.20θb, the angle difference between them is set to 20% or less of the inclination angle θb, and the belt cord C5 and the organic fiber cord The deviation from C6 is not too large. As a result, it is possible to prevent the so-called tagging effect from occurring and prevent the binding force from becoming too large. For the same reason, the angle formed by the belt cord C5 and the organic fiber cord C6 is preferably 60 degrees or less.

  The pneumatic tire of the present invention can be configured in the same manner as a normal pneumatic tire except for having the above-described configuration, and any conventionally known material, shape, structure, manufacturing method, etc. can be adopted in the present invention. it can. Therefore, for example, the belt layer may have a structure of three or more layers including the third belt ply provided on the outer periphery of the second belt ply.

  The present invention is not limited to the embodiment described above, and various improvements and modifications can be made without departing from the spirit of the present invention.

  Examples that specifically show the structure and effects of the present invention will be described below. Each performance evaluation of the tire was performed as follows.

(1) High speed durability
A speed test [km / h] when a tire is damaged (puncture, burst, separation, etc.) by running a test with a drum tester in accordance with the extension conditions specified in ECE-R54 (ECONOMIC COMMISSION FOR EUROPE REGULATION No.54) And time [min. ] Was measured. The result of Comparative Example 1 is evaluated with an index of 100, and the higher the value, the better the high-speed durability.

(2) Separation resistance A running test using a drum-type testing machine is performed in accordance with the extension conditions stipulated in the US automobile safety standard FMVSS 139, and the running time until a separation failure is recognized starting from the end of the belt layer is measured. did. The result of Comparative Example 1 is evaluated with an index of 100, and the larger the value, the better the separation resistance.

(3) Uniformity (conicity)
Conformity was measured with a uniformity tester under the conditions of an internal pressure of 200 kPa and a load of 4.6 kPa according to the test method specified in JIS D4233, and the reciprocal of the measured value was calculated. The result of Comparative Example 1 was evaluated with an index of 100, and the larger the value, the smaller the conicity and the better the uniformity.

  For the evaluation, the pneumatic tire (size: LT265 / 70R17) according to the above-described embodiment is provided, and the tire structure is common except for the matters described in Table 1. In Table 1, in the “fiber reinforcement layer”, the structure in which the inclination directions of the left and right organic fiber cords are opposite to each other as shown in FIG. did. In addition, in “Rubber out of the rubber pad”, the structure in which the rubber pad is completely covered with the fiber reinforcing layer as shown in FIG. 2 is “None”, and the rubber pad is protruded outside the fiber reinforcing layer in the tire width direction. Yes. "

  As shown in Table 1, in Comparative Example 2, the uniformity is deteriorated. In Comparative Example 4, the high speed durability is relatively low, and in Comparative Example 5, the separation resistance is relatively low. On the other hand, in each embodiment, high-speed durability and separation resistance can be improved without impairing uniformity.

DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Carcass layer 5 Belt layer 6 Fiber reinforcement layer 7 Rubber pad 51 First belt ply 52 Second belt ply C5 Belt cord C6 Organic fiber cord

Claims (3)

A carcass layer provided between a pair of bead portions;
A belt layer including a first belt ply provided on an outer periphery of the carcass layer and a second belt ply provided on an outer periphery of the first belt ply;
A pair of fiber reinforcement layers covering both ends of the first and second belt plies;
A pair of rubber pads interposed between the end of the first belt ply and the carcass layer;
Each of the first and second belt plies includes a belt cord extending in a direction inclined with respect to the tire circumferential direction,
The fiber reinforcement layer includes an organic fiber cord extending in a direction inclined with respect to the tire circumferential direction,
Of the pair of fiber reinforcing layers, the inclination direction of the organic fiber cord included in one and the inclination direction of the organic fiber cord included in the other are opposite to each other, and both the organic fiber cords are in the first belt. It extends in the direction crossing the ply belt cord,
The inclination angle θb of the belt cord of the first belt ply with respect to the tire circumferential direction and the inclination angle θs of the organic fiber cord of the fiber reinforcement layer with respect to the tire circumferential direction are 0.8θb ≦ θs ≦ 0.95θb or 1.05θb ≦ A pneumatic tire that satisfies the relationship θs ≦ 1.20θb.   The tire width direction outer side edge part of the said fiber reinforcement layer is arrange | positioned in the tire width direction outer side rather than the tire width direction outer side edge part of the said rubber pad located in the inner peripheral side of the fiber reinforcement layer. The described pneumatic tire.   The end of the fiber reinforcing layer on the inner side in the tire width direction is disposed on the inner side in the tire width direction of the end of the rubber pad located on the inner peripheral side of the fiber reinforcing layer in the tire width direction. 2. The pneumatic tire according to 2.

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