JP6113629B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a structure in which a carcass ply is wound up from the outside in the tire width direction.

  Conventionally, as shown in Patent Documents 1 to 3 below, by rolling up the carcass ply from the outside in the tire width direction to the inside, the distribution of the tension applied to the carcass ply is changed, and the tension at a position that easily contributes to tire rigidity is reduced. There are known pneumatic tires that increase and improve steering stability performance.

  In the following Patent Document 1, the carcass layer has a single-layer structure, and is wound around the bead core from the outer side in the tire width direction, the end of the carcass layer is disposed on the inner side in the tire radial direction of the bead core, and the end of the carcass layer A pneumatic tire intended to improve the steering stability of the tire is shown by winding the portion from the turn-up position toward the outer side in the tire radial direction so as not to wrap the bead core.

  Patent Document 2 listed below discloses a tire whose purpose is to substantially reduce the frequency of occurrence of early tire breakage by winding a carcass ply around the bead core from the outside in the tire width direction to the inside.

  In the following Patent Document 3, the carcass ply passes through the tire outer surface side from the bead filler, and both ends of the ply are supported by being wound up from the outer side to the inner side with respect to the bead cores on both sides. A pneumatic radial tire that can contribute to weight reduction of the tire and maintain rigidity without degrading the performance of is shown.

JP 2007-131173 A JP 2002-513360 Gazette JP 7-315013 A

  However, in all of the known techniques disclosed in Patent Documents 1 to 3, since the carcass ply is in direct contact with the bead core, when the internal pressure is applied to the tire, the carcass is generated by tension. There is a problem that the ply and the bead core are rubbed and broken to deteriorate durability.

  In addition, the inner liner and rubber chacher that make up the pneumatic tire are made of rubber with a high hardness in the rubber chacher and rubber with a low hardness in the inner liner. Due to the difference in hardness between the topping rubber of the carcass ply located between the inner liner and the rubber chafer, adhesion and distortion suppression may be insufficient, and as a result, separation may occur.

  In the present invention, the carcass ply is wound around the bead core from the outer side in the tire width direction to the inner side in the tire width direction, both end portions of the inner liner extend between the bead core and the carcass ply, and the inner liner is a bead core. In the pneumatic tire wound around from the inner side in the tire width direction to the outer side in the tire width direction, by configuring the topping rubber on the front and back of the carcass ply with rubbers of different blends with different hardness, the adhesion between the members is improved, An object is to provide a pneumatic tire with improved durability.

  A pneumatic tire according to a first aspect of the present invention includes a pair of left and right beads including a bead core, a carcass ply spanned over the bead core, and an inner liner disposed on an inner peripheral side of the carcass ply. In the pneumatic tire, the carcass ply is wound around the bead core from the outer side in the tire width direction to the inner side in the tire width direction, and both end portions of the inner liner extend between the bead core and the carcass ply, The inner liner is wound around the bead core from the inner side in the tire width direction to the outer side in the tire width direction, and a rubber chacher is arranged around the bead core. The carcass ply has topping rubber on the front and back sides. The topping rubber has a carcass ply in contact with the rubber chafer. The hardness of that side of the topping rubber, in which the carcass ply is characterized by being composed of rubber of high different formulation than the hardness of the topping rubber of the side in contact with the inner liner.

  With the above-described configuration, the pneumatic tire according to the present invention has a structure in which the tension of the carcass ply is changed by the structure in which the carcass ply is wound from the outer side in the tire width direction to the inner side. The tension from the outer shoulder region to the maximum width position of the tire is increased, resulting in high rigidity. On the other hand, by placing the inner liner as a cushioning material between the bead core and the carcass ply, the bead core and the carcass ply can be directly contacted and rubbed when a high tension state is reached without any additional cushioning member. Can be prevented without increasing the weight.

  In addition, the hardness difference between the top liner of the carcass ply in contact with the inner liner of the low hardness rubber and the inner liner is reduced to improve adhesion, and the topping rubber and rubber cha of the carcass ply in contact with the high hardness rubber chafer And the hardness difference is reduced to improve the adhesion.

  A pneumatic tire according to a second aspect of the present invention is the pneumatic tire according to the first aspect, wherein the rubber of the different composition has a 300% modulus value of the rubber on the side in contact with the inner liner. The rubber constituting the rubber is less than the 300% modulus value, and the rubber contacting the rubber chacher has a 300% modulus value equal to or greater than the rubber constituting the rubber chacher. is there. Specifically, the 300% modulus value of the rubber on the side in contact with the inner liner is in the range of 50% to 95% of the 300% modulus value of the rubber constituting the inner liner, and the rubber on the side in contact with the rubber chafer. The 100% modulus value of the rubber is desirably in the range of 105% to 150% of the 100% modulus value of the rubber constituting the rubber chacher.

  The pneumatic tire according to a third aspect of the present invention is the pneumatic tire according to the first or second aspect, wherein the rubber of the different composition is at least a rolled-up end portion of the carcass ply from a rolled-up end portion of the inner liner. It is characterized by being arranged between.

  In the pneumatic tire of the present invention, as described above, the carcass ply is wound around the bead core from the outer side in the tire width direction to the inner side in the tire width direction, and both end portions of the inner liner are between the bead core and the carcass ply. Thus, a lightweight and highly rigid tire can be obtained, and the steering stability performance can be improved.

  In addition, the adhesion between the carcass ply and the inner liner is improved, and the adhesion between the carcass ply and the rubber chacher is improved, so that the distortion between the inner liner, the carcass ply and the rubber chacher is suppressed. This reduces the occurrence of separation and improves tire durability.

It is an A partial enlarged view general | schematic fragmentary sectional view of the bead periphery in the pneumatic tire which concerns on Example 1 of this invention. It is a partial schematic diagram which shows the internal structure of the carcass ply in the pneumatic tire which concerns on Example 1 of this invention. It is explanatory drawing which shows the adhesion state of the inner liner, carcass ply, and rubber chacher in the pneumatic tire which concerns on Example 1 of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

  The outline of Example 1 is that the carcass ply is wound around the bead core from the outer side in the tire width direction to the inner side in the tire width direction, and both end portions of the inner liner extend between the bead core and the carcass ply. Structure.

  1 to 3 show a first embodiment, and FIG. 1 shows a periphery of a bead portion of the pneumatic tire according to the first embodiment. The pneumatic tire includes a tire tread, a sidewall 2 and a bead 3. The bead 3 includes a bead core 3a and a bead filler 3b made of hard rubber extending outward in the tire radial direction from the bead core 3a.

  Reference numeral 4 denotes an inner liner disposed on the inner surface of the tire, and both end portions extend between the bead core 3a and the carcass ply. The configuration of both end portions is not particularly limited, but a form wound around the bead core 3a from the inner side in the tire width direction to the outer side in the tire width direction is preferable in terms of durability.

  Reference numeral 5 denotes a carcass ply, and the carcass ply 5 is disposed so as to straddle between the bead cores 3 a across the tire tread, the sidewalls 2, and the beads 3, and around the bead cores 3 a from the outer side in the tire width direction. It is wound up inward in the tire width direction.

  The inner liner 4 and the carcass ply 5 are arranged inside the carcass ply 5 around the bead core 3a.

  Reference numeral 6 denotes a rubber chacher, which is disposed around the bead core 3 a so as to cover the inner liner 4 and the carcass ply 5. Specifically, the arrangement of the rubber chacher 6 covers the portion where the bead 3 comes into contact with the rim when assembling the rim, and at least the end of the rubber chacher 6 so as to cover the end portion 5a where the carcass ply 5 is wound up. The portion is terminated on the inner liner 4. Therefore, the inner liner 4 and the carcass ply 5 are not exposed on the surface of the bead 3 including their end portions 4a and 5a.

  The carcass ply 5 has a carcass cord 5b arranged in parallel as shown in FIG. 2 and is coated with topping rubbers a and b on both sides thereof. The topping rubber a is a topping rubber. It is a rubber composition of a different blend whose rubber hardness is lower than b. The topping rubbers a and b have the topping rubber a bonded to the inner liner 4 side and the topping rubber b bonded to the rubber chafer 6 side, as shown in the enlarged view of part A of FIG. 1 and FIG. Yes. That is, the topping rubber a bonded to the inner liner 4 side is designed to have a lower rubber hardness than the topping rubber b bonded to the rubber chafer 6 side.

  In addition, the carcass ply 5 having the different topping rubbers a and b is disposed between the winding end 4 a of the inner liner 4 and the winding end 5 a of the carcass ply 5. The entire length of the carcass ply 5 may be covered with different topping rubbers a and b, which is convenient because of the ease of manufacturing the carcass ply 5 and the pneumatic tire.

  In Example 1, the 300% modulus value of the inner liner 4 is set to 2.5 MPa, and the 300% modulus value of the topping rubber a bonded to the inner liner 4 is set to 2.0 MPa.

  On the other hand, the 300% modulus value of the rubber chafer 6 is 4.0 MPa, and the 300% modulus value of the topping rubber b bonded to the rubber chacher 6 is 4.5 MPa.

  Thus, in Example 1, the order of the rubber hardness is the topping rubber b, the rubber chafer 6, the inner liner 4, and the topping rubber a in descending order of the 300% modulus value.

  As described above, the pneumatic tire according to this embodiment has a structure in which the carcass ply 5 is wound from the outer side in the tire width direction to the inner side, so that the tension distribution applied to the carcass ply 5 is changed and the rigidity is increased. In the pneumatic tire according to the present embodiment, the inner liner 4 is disposed between the bead core 3a and the carcass ply 5 so that the bead core 3a and the carcass ply 5 do not directly contact each other. Therefore, there is no need to add a special cushioning member to prevent breakage due to direct contact between the bead core and the carcass ply when it becomes a high tension state, so that the bead core and the carcass ply are not increased in weight. Can be prevented from breaking.

  Since the topping rubbers a and b of the carcass ply 5 are differently blended so that the rubber hardness is different, the difference in hardness between the topping rubber a of the carcass ply 5 and the inner liner 4 is reduced, and the adhesiveness is improved. The difference in hardness between the topping rubber b of the carcass ply 5 and the rubber chafer 6 is reduced and the adhesion is improved, so that the distortion is suppressed, the occurrence of separation is reduced, and the durability of the tire is improved.

  In Example 2, the 300% modulus values of the topping rubbers a and b in the configuration of Example 1 are changed as follows.

  That is, in Example 2, the 300% modulus value of the inner liner 4 and the 300% modulus value of the rubber chafer 6 are configured in the same manner as in Example 1, and the 300% modulus value of the topping rubber a bonded to the inner liner 4 is set. Is changed to 3.3 MPa, and the 300% modulus value of the topping rubber b bonded to the rubber chacher 6 is changed to 3.7 MPa.

  Thus, in Example 2, the rubber hardness in order of rubber hardness is from the one with the highest 300% modulus value, rubber topher 6, topping rubber b that adheres to rubber chacher 6, and topping rubber that adheres to inner liner 4. a, Inner liner 4

  As described above, even when the 300% modulus values of the topping rubbers a and b in Example 1 are changed as in Example 2, the hardness of the topping rubber on the side where the carcass ply contacts the inner liner is low, and the carcass ply Since the topping rubber on the side in contact with the rubber chacher is composed of a differently compounded rubber, the hardness difference between the topping rubber of the carcass ply and the inner liner is reduced to improve adhesion, and the topping rubber of the carcass ply Since the hardness difference with the rubber chacher is reduced and the adhesion is improved, there is an effect of suppressing the distortion and reducing the occurrence of separation and improving the durability of the tire.

[Configuration of Comparative Example 1]
In Comparative Example 1, the 300% modulus value of the inner liner 4 and the 300% modulus value of the rubber chafer 6 are configured in the same manner as in Example 1, and the 300% modulus values of the topping rubbers a and b in the configuration of Example 1 are used. This is an example in which the 300% modulus values of both topping rubbers are set to the same 3.5 MPa.

  When configured in this manner, the hardness difference between the topping rubber of the carcass ply and the inner liner is increased, the adhesiveness is lowered, and the hardness difference between the topping rubber of the carcass ply and the rubber chacher is increased. Since the adhesiveness is reduced, the strain suppression is reduced, separation may occur, and the durability of the tire may be reduced.

[Comparison test]
Next, for the pneumatic tire according to the present invention, a comparative test was performed on the above-described Example 1, Example 2, and Comparative Example 1 under the following conditions. The results are shown in Table 1 below.

Test tire size: 195 / 65R15 91H
Test vehicle: Domestic 1.8L sedan Test item In order to evaluate tire distortion suppression, tire lateral stiffness was measured in a tire stiffness test. The result of Comparative Example 1 was evaluated as an index with the index being 100, and the larger the index, the higher the rigidity value and the better the strain suppression.

  In order to evaluate the durability, the distance traveled until the tire failed was measured by a test method based on FMVSS139. The result of Comparative Example 1 was evaluated as an index with the value of 100, and the greater the index, the better the durability.

  In order to evaluate the steering stability, a sensory evaluation of the actual vehicle handling stability was performed. The result of Comparative Example 1 was evaluated as an index with the value 100, and the larger the index, the better the steering stability.

[Results of comparative test]
Example 1 and Example 2 were both superior to Comparative Example 1 in terms of lateral rigidity, and the results were that distortion suppression was exhibited.

  Further, both Example 1 and Example 2 were superior to Comparative Example 1 in durability.

  Furthermore, both Example 1 and Example 2 were excellent in steering stability as compared with Comparative Example 1, or the same results were obtained.

  Based on the above test results, it was found that the hardness of the topping rubber on the side where the carcass ply contacts the inner liner is composed of a rubber having a different composition than the hardness of the topping rubber on the side where the carcass ply contacts the rubber chafer. It has been found that the generation is reduced and distortion suppression and durability are improved.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

2. Side wall 3 ... Bead 3a ... Bead core 3b ... Bead filler 4 ... Inner liner 4a ... End 5 where the inner liner is wound up ... Carcass ply 5a ... Carcass ply is wound up End 5b …… Carcass cord a ……… Topping rubber b on the inner liner side in the carcass ply ………… Topping rubber 6 on the rubber chacher side in the carcass ply ……… Rubber chaher

Claims (3)

In a pneumatic tire having a pair of left and right beads including a bead core, a carcass ply spanned over the bead core, and an inner liner disposed on an inner peripheral side of the carcass ply,
The carcass ply is wound around the bead core from the outside in the tire width direction to the inside in the tire width direction,
Both end portions of the inner liner extend between the bead core and the carcass ply,
The inner liner is wound around the bead core from the inside in the tire width direction to the outside in the tire width direction,
Around the bead core, a rubber chafer is placed,
The carcass ply has topping rubber on its front and back,
The topping rubber is characterized in that the topping rubber on the side where the carcass ply comes into contact with the rubber chacher is made of a rubber having a different composition than the hardness of the topping rubber on the side where the carcass ply comes into contact with the inner liner. Pneumatic tire. The different compound rubber is
The 300% modulus value of the rubber in contact with the inner liner is equal to or less than the 300% modulus value of the rubber constituting the inner liner;
The pneumatic tire according to claim 1, wherein a 300% modulus value of rubber on a side in contact with the rubber chacher is equal to or greater than a 300% modulus value of rubber constituting the rubber chacher. 3. The pneumatic tire according to claim 1, wherein the differently compounded rubber is disposed at least between a winding end of the inner liner and a winding end of the carcass ply.

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