JP2012179944A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire which has improved lateral stiffness, thereby having improved driving stability while suppressing increase in a tire mass or decrease in durability.SOLUTION: The pneumatic radial tire includes, between a carcass body 2A and a folded portion 2B in a sidewall section 12, an organic fiber reinforced layer 3 adjoining to the outside in a tire width direction of the carcass body 2A, and a metal reinforced layer 4 adjoining the inside in the tire width direction of the folded portion 2B. The tire radial-direction outer end 3a of the organic fiber reinforced layer is located more outside in the tire radial direction than a maximum tire width position P and located at a height in the range from 50 to 80% of the tire cross-sectional height SH. A tire radial-direction outer end 4a of the metal reinforced layer is located more inside in the tire radial direction than the tire maximum width position P. The organic fiber reinforced layer and the metal reinforced layer are arranged to be in contact with each other or to include an overlapping portion in the tire radial direction.

Description

  The present invention relates to a pneumatic radial tire (hereinafter, also simply referred to as “tire”), and more particularly to a pneumatic radial tire according to an improvement of a sidewall portion.

  In a pneumatic radial tire, in order to improve steering stability performance, it is necessary to increase lateral rigidity. Therefore, conventionally, a high-strength steel reinforcing layer 21 is disposed from the sidewall portion to the periphery of the bead portion to increase the amount of steel, thereby ensuring lateral rigidity (see FIGS. 3A and 3B). ). In addition, a technique is known in which the reinforcing layer 22 made of fibers is folded around the bead core 1 and the lateral stiffness is controlled by increasing the amount of fibers (see FIG. 3C).

  Further, as a technique related to the improvement of the sidewall portion of the tire, for example, Patent Document 1 discloses a first side reinforcing layer on the side portion and at least a part of the maximum width portion of the pneumatic tire in the tread width direction. A pneumatic tire is disclosed that includes an overlap region that overlaps with the first side reinforcing layer and a second side reinforcing layer that is provided on the outer side in the tread width direction than the first side reinforcing layer.

No. 2006-003742 (Claims etc.)

  However, in the case of the conventional technology for controlling the lateral rigidity by the arrangement of the steel reinforcing layer, there is a problem that the tire mass increases due to the increase in the steel amount or the tire durability deteriorates. Similarly, the technique for controlling the lateral stiffness by the fiber reinforcement layer also has a problem that the tire mass is greatly increased by an increase in the fiber amount, and there is a problem that the tire stiffness cannot be sufficiently secured.

  Accordingly, an object of the present invention is to provide a pneumatic radial tire that solves the above-described problems and suppresses an increase in tire mass and a decrease in durability while improving lateral rigidity and improving steering stability. There is to do.

  As a result of earnest study, the present inventor, as a structure in which the carcass is folded up to the tread portion, an organic fiber reinforcing layer and a metal reinforcing layer are provided at predetermined positions on the sidewall portion between the carcass main body portion and the folded portion. It has been found that the above-mentioned problems can be solved by arranging them in combination, and the present invention has been completed.

That is, the pneumatic radial tire of the present invention has a tread portion and a pair of sidewall portions and bead portions that are connected to both ends of the tread portion in the tire width direction, and a pair of buried tires embedded in the pair of bead portions. In a pneumatic radial tire having a carcass made of a carcass made of one or more carcass plies composed of a main body extending in a toroidal shape between bead cores and a folded portion folded around the bead core,
An organic fiber reinforcing layer adjacent to the outer side in the tire width direction of the carcass main body portion and an inner side in the tire width direction of the carcass folding portion between the carcass main body portion and the turned back portion of the sidewall portion. A metal reinforcing layer that is formed, and an outer end portion in the tire radial direction of the organic fiber reinforcing layer is located on the outer side in the tire radial direction from the tire maximum width position, and is present at a height of 50 to 80% of a tire cross-section height. The outer end portion in the tire radial direction of the metal reinforcing layer is present on the inner side in the tire radial direction from the tire maximum width position, and the organic fiber reinforcing layer and the metal reinforcing layer are in contact with each other in the tire radial direction, or , And is arranged so as to have an overlap portion.

  In this invention, it is preferable that the said organic fiber reinforcement layer and the said metal reinforcement layer are spaced apart in the tire width direction in the said overlap part. The length x of the overlap portion is preferably 25 mm or less. Furthermore, in the present invention, in the overlap portion, a hard rubber harder than the coating rubber of the organic fiber reinforcement layer and the metal reinforcement layer is disposed between the organic fiber reinforcement layer and the metal reinforcement layer. It is preferable.

  According to the present invention, the above configuration makes it possible to improve the lateral rigidity while suppressing an increase in tire mass and a decrease in durability, and achieve air handling stability, high-speed durability, and light weight at the same time. It has become possible to realize a radial tire with an inside.

It is a width direction one side sectional view showing an example of the pneumatic radial tire of the present invention. It is a width direction one side sectional view showing other examples of the pneumatic radial tire of the present invention. (A)-(c) is a width direction one side sectional view which shows an example of the conventional pneumatic radial tire.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional side view in the width direction showing an example of a pneumatic radial tire of the present invention. As shown in the figure, the pneumatic radial tire of the present invention has a tread portion 11 and a pair of sidewall portions 12 and bead portions 13 connected to both ends in the tire width direction. The tire according to the present invention includes a main body portion 2A extending in a toroidal shape between a pair of bead cores 1 embedded in a pair of bead portions 13 and a folded portion 2B folded around the bead core 1 1. A carcass composed of at least one carcass ply 2 is used as a skeleton.

  In the tire of the present invention, the organic fiber reinforcing layer 3 adjacent to the outer side in the tire width direction of the carcass main body portion 2A and the carcass folding portion between the carcass main body portion 2A and the folding portion 2B of the sidewall portion 12 are provided. And a metal reinforcing layer 4 adjacent to the inner side in the tire width direction of 2B. Of these, the organic fiber reinforcing layer 3 has an outer end portion 3a in the tire radial direction that is on the outer side in the tire radial direction from the tire maximum width position P and exists at a height of 50 to 80% of the tire cross-section height SH. Further, the metal reinforcing layer 4 is arranged such that the tire radial direction outer end portion 4a exists on the inner side in the tire radial direction from the tire maximum width position P. In the present invention, it is important that the organic fiber reinforcing layer 3 and the metal reinforcing layer 4 are arranged so as to contact each other in the tire radial direction or have an overlap portion.

  When the steel reinforcing layer is disposed at a location where the tire cross-section height SH is large as shown in FIG. 3B as in the conventional case (FIG. 3B), the upper end of the steel reinforcing layer urges the carcass material, However, in the present invention, the metal reinforcing layer 4 is not disposed on the outer side in the tire radial direction from the maximum tire width position P, and is disposed only on the inner side in the tire radial direction. Therefore, such a problem does not occur. On the other hand, in the present invention, since the metal reinforcement layer 4 is disposed in the region radially inward of the tire from the tire maximum width position P, it can be obtained by the conventional arrangement of only the fiber reinforcement layer (FIG. 3C). It was possible to obtain a high lateral rigidity that was not present, thereby improving the steering stability. In the present invention, since the organic fiber reinforcement layer 3 is provided in place of the metal reinforcement layer 4 in the region radially outside the tire maximum width position P, the conventional steel reinforcement layer or fiber reinforcement layer is used alone. The amount of the reinforcing material used can be substantially reduced as compared with the case where it is arranged in the above. Therefore, according to the present invention, the combination of the organic fiber reinforcing layer 3 and the metal reinforcing layer 4 improves the steering stability and the light weight while maintaining durability, and highly balances these performances. Is now possible. In the present invention, the tire cross-section height SH means 1/2 of the difference between the tire outer diameter and the rim diameter. Further, in the present invention, the height reference of the organic fiber reinforcement layer 3 and the metal reinforcement layer 4 is a straight line that forms an angle of 45 ° from the center of the bead core 1 to the outside in the tire width direction with respect to the inside in the tire radial direction. At this time, it is defined as a position in the tire radial direction at a point Q where the straight line intersects with the tire outline.

  Here, in the present invention, the organic fiber reinforcement layer 3 and the metal reinforcement layer 4 are arranged so as to contact each other in the tire radial direction when the organic fiber reinforcement layer 3 and the metal reinforcement layer are viewed in the tire radial direction. 4 means that they are continuously arranged so that no gap is generated between the layers. In addition, when the organic fiber reinforcing layer 3 and the metal reinforcing layer 4 are arranged so as to have an overlap portion, the length x of the overlap portion is preferably 25 mm or less. The case of x = 0 mm corresponds to the case where the organic fiber reinforcing layer 3 and the metal reinforcing layer 4 are disposed so as to contact each other in the tire radial direction. The length x of the overlap portion needs to be 0 mm or more, preferably 25 mm or less, more specifically more than 0 mm and 25 mm or less, and particularly preferably 15 to 20 mm. When the length x of the overlap portion of the organic fiber reinforcement layer 3 and the metal reinforcement layer 4 is less than 0 mm, that is, when the organic fiber reinforcement layer 3 and the metal reinforcement layer 4 are arranged apart from each other in the tire radial direction. Since the rigidity step is generated between the reinforcing layers, the durability is lowered, and the desired effect of the present invention cannot be obtained.

  In this invention, the tire radial direction inner side edge part 3b of the organic fiber reinforcement layer 3 shall exist suitably in the height of 20 to 50% of tire cross-section height SH. If the position of the inner end portion 3b in the tire radial direction of the organic fiber reinforcing layer 3 is too high, the amount of overlap with the metal reinforcing layer 4 is less than zero and the durability deteriorates, and if it is too low, the longitudinal rigidity increases. This is not preferable in any case because the ride performance deteriorates.

  In the present invention, the tire radial direction outer side end 4a of the metal reinforcing layer 4 is preferably present at a height of 50% or less, particularly 20 to 50% of the tire cross-section height SH. If the position of the outer end 4a in the tire radial direction of the metal reinforcing layer 4 is too low, the effect of improving the lateral rigidity is lowered, which is not preferable. Furthermore, the tire radial direction inner side edge part 4b of the metal reinforcement layer 4 can be arrange | positioned to bead core 1 vicinity, for example, Preferably, it exists in the height of 5-10% of tire cross-section height SH. To do. If the position of the end portion 4b in the tire radial direction of the metal reinforcing layer 4 is too high, the effect of improving the lateral rigidity is lowered, and if it is too low, the durability deteriorates due to contact with the bead core. It is not preferable.

  Moreover, in this invention, it is preferable that the organic fiber reinforcement layer 3 and the metal reinforcement layer 4 are spaced apart in the tire width direction in the said overlap part so that it may show in figure. In this case, the distance y between the cords between the organic fiber reinforcing layer 3 and the metal reinforcing layer 4 is preferably in the range of 0.5 to 1.5 mm in the thickness direction of the layer (see FIG. 2). . By separating the organic fiber reinforcing layer 3 and the metal reinforcing layer 4 in the tire width direction, it is possible to suppress the occurrence of rubber cracks and cord breaks due to deformation of members generated between these reinforcing layers. Here, the case where the organic fiber reinforcing layer 3 and the metal reinforcing layer 4 are separated from each other means a mode in which another member such as a stiffener is sandwiched between the organic fiber reinforcing layer 3 and the metal reinforcing layer 4, and It includes both forms in which the distance between the organic fiber reinforcing layer 3 and the metal reinforcing layer 4 is wide even if not sandwiched.

  In this case, it is preferable that a hard rubber harder than the coating rubber of each layer is disposed between the organic fiber reinforcing layer 3 and the metal reinforcing layer 4 in the overlap portion. Thereby, generation | occurrence | production of the crack of the said rubber | gum and the fracture | rupture of a code | cord | chord can be suppressed more effectively, and durability can be improved more. As such a hard rubber, those having a dynamic storage elastic modulus E ′ at 30 ° C. of 50 to 3000 MPa can be suitably used. The dynamic storage elastic modulus E ′ is obtained by statically applying an initial load of 150 g to a sample having a thickness of 2.0 mm, a width of 5.0 mm, and a length of 20 mm using, for example, a spectrometer manufactured by Toyo Seiki Co., Ltd. It can be obtained by measuring at a test temperature of 30 ° C. under conditions of an average strain amplitude of 1% and a frequency of 32 Hz. Specifically, in the present invention, the outer end portion in the tire radial direction of the bead filler 5 arranged on the outer side in the tire radial direction of the bead core 1 is the outer side in the tire radial direction from the outer end portion 4a in the tire radial direction of the metal reinforcing layer 4. Can be used as the hard rubber (see FIG. 2). Further, when the outer end portion in the tire radial direction of the bead filler 5 is located on the inner side in the tire radial direction from the outer end portion 4a in the tire radial direction of the metal reinforcing layer 4, the organic fiber reinforcing layer 3 and the metal reinforcing layer 4 In addition, a hard rubber sheet 6 may be appropriately disposed as a hard rubber (see FIG. 1). In this case, the arrangement condition of the hard rubber sheet 6 is not particularly limited.

  In the present invention, the organic fiber reinforcing layer 3 can be composed of a rubberized layer of an organic fiber cord, and examples of the organic fiber include nylon, aramid fiber, and polyester. The cord structure of the organic fiber cord is, for example, 900 dtex / 1 or more. The number of organic fiber cords driven into the organic fiber reinforcing layer 3 can be set to, for example, 30 to 45 pieces / 50 mm. Furthermore, the cord angle of the organic fiber reinforcing layer 3 is preferably 30 to 60 ° with respect to the tire circumferential direction.

  The metal reinforcing layer 4 can be made of a rubberized layer of a metal cord made of steel or the like, and the cord diameter is, for example, 0.6 mm or more. In addition, the number of metal cords driven into the metal reinforcing layer 4 can be set to 25 to 35 pieces / 50 mm, for example. Furthermore, the cord angle of the metal reinforcing layer 4 is preferably 30 to 60 ° with respect to the tire circumferential direction. In the present invention, the cord angles of the organic fiber reinforcing layer 3 and the metal reinforcing layer 4 are made to intersect each other.

  In the present invention, only the point that the organic fiber reinforcing layer 3 and the metal reinforcing layer 4 are provided in a predetermined arrangement is important, and other details of the tire structure can be appropriately determined according to a conventional method. There is no particular limitation.

  For example, for the carcass ply 2 constituting the carcass, it is necessary that at least one sheet has a structure composed of the main body 2A and the folded portion 2B as shown in the figure, but two or more sheets may be used. The material is not particularly limited. Further, as shown in the figure, at least one, preferably two or more belt layers 7 can be disposed on the outer side in the radial direction of the crown portion of the carcass. The belt layer 7 is usually composed of a rubberized layer of a cord that extends at an inclination with respect to the tire equatorial plane, and preferably a rubberized layer of a steel cord. The belt layer 7 is formed by being laminated so as to intersect with each other with the equator plane interposed therebetween. The folded portion 2B of the carcass ply 2 can normally be disposed on the inner side in the tire radial direction of the belt layer 7 as illustrated.

  Further, although not shown, on the outer side in the tire radial direction of the belt layer 7, as a belt reinforcing layer, one or more cap layers covering the entire belt layer 7 and a pair of one or more covering only both ends of the belt layer 7 are provided. Layer layers can also be placed. Such a belt reinforcing layer is usually composed of a rubberized layer of cords arranged substantially parallel to the tire circumferential direction, and either one of them may be arranged alone or in combination with each other. There is also no particular limitation on the number of sheets arranged. In the present invention, it is not essential to dispose the belt reinforcing layer, and belt reinforcing layers having other structures and the number of layers may be disposed.

  Furthermore, the illustrated tire includes a rim guard 8 having a substantially triangular cross section on the outer side in the tire width direction of the folded portion 2B of the carcass 2 in the region extending from the sidewall portion 12 to the bead portion 13. In the present invention, Arrangement of the rim guard 8 is not essential, and rim guards of other shapes can be arranged. In the present invention, the tire maximum width position means the maximum width position of the tire when the rim guard 8 is not provided.

  Furthermore, in the tire of the present invention, a tread pattern is appropriately formed on the surface of the tread portion 11, and an inner liner (not shown) is formed in the innermost layer. Furthermore, in the illustrated tire of the present invention, as the gas filled in the tire, normal or air having a changed oxygen partial pressure, or an inert gas such as nitrogen can be used.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Conventional example 1>
In tire size 305 / 30ZR20, it has a tread portion and a pair of sidewall portions and bead portions connected to both ends in the tire width direction, and a main body portion extending in a toroid shape between the pair of bead cores, and around the bead core A pneumatic radial tire having a carcass made of one carcass ply (material: rayon) composed of a folded portion folded in step 1 was produced. Further, a belt layer made of two belts (material: steel) intersecting each other at an angle of ± 30 ° with respect to the tire equator plane was disposed on the outer side in the tire radial direction of the crown portion of the carcass. The maximum tire width position was 22% of the tire cross-section height from the lower end of the bead core.

  As shown in FIG. 3 (a), the metal reinforcement adjacent to the inner side in the tire width direction of the folded portion of the carcass is provided between the main body portion and the folded portion of the side wall portion in accordance with the conditions shown in the following table. Layers (cord diameter: 1.12 mm, driving number: 32.5 / 50 mm, cord angle: 45 ° with respect to the tire circumferential direction) were arranged.

<Conventional example 2>
As shown in FIG. 3B and the following table, a pneumatic radial tire was produced in the same manner as in the conventional example 1 except that the arrangement region of the metal reinforcing layer was changed.

<Conventional example 3>
As shown in FIG. 3C and the following table, a reinforcing layer made of fibers according to the conditions shown in the following table, between the main body part and the turned-up part of the carcass in the sidewall portion, instead of the metal reinforcing layer. A pneumatic radial tire is manufactured in the same manner as in Conventional Example 1 except that (aramide fiber cord, number of driven: 35.7 pieces / 50 mm, cord angle: 45 ° with respect to the tire circumferential direction) is folded and arranged around the bead core. did.

<Example 1>
As shown in FIG. 1 and the following table, an organic fiber reinforcing layer (aramid fiber cord, driven-in) adjacent to the outer side in the tire width direction of the carcass main body portion between the carcass main body portion and the folded portion of the sidewall portion. Number: 35.7 pieces / 50 mm, cord angle: + 45 ° with respect to the tire circumferential direction, and a metal reinforcing layer (cord diameter: 1.12 mm, number of drivings: 32. adjacent to the inner side in the tire width direction of the folded portion of the carcass. A pneumatic radial tire was produced in the same manner as in Conventional Example 1 except that 5 pieces / 50 mm and cord angle: −45 ° (direction intersecting with the organic fiber reinforcing layer) with respect to the tire circumferential direction were arranged.

<Example 2>
As shown in the following table, a pneumatic radial tire was produced in the same manner as in Example 1 except that the arrangement region of each reinforcing layer was changed.

<Example 3, Comparative Example 1>
As shown in the table below, a pneumatic radial tire was manufactured in the same manner as in Example 2 except that the length x of the overlap portion was changed by changing the arrangement region of the inner reinforcing layer.

<Examples 4 and 5>
As shown in the table below, a pneumatic radial tire was produced in the same manner as in Example 2 except that the interval y between the reinforcing layers was changed.

<Tire mass>
The mass of each of the obtained test tires was measured and indicated by an index with the test tire of Conventional Example 1 being 100. The higher the number, the better the result.

<Steering stability>
Each of the obtained test tires was assembled on a rim having a rim size of 20 × 11 J, filled with an internal pressure of 250 kPa, and mounted on an actual vehicle (vehicle type: PORSCHE 997), and sensory evaluation was performed by a test driver. The results are shown as an index with the test tire of Conventional Example 1 as 100. The higher the number, the better the result.

<Rigid rigidity>
Each of the obtained test tires was assembled in a rim having a rim size of 20 × 11 J, filled with an internal pressure of 250 kPa, and subjected to indoor evaluation under the condition of applying a load of 6 kN. The results are shown as an index with the test tire of Conventional Example 1 as 100. The higher the number, the better the result.

<Durability>
Each of the obtained test tires was assembled in a rim having a rim size of 20 × 11 J, filled with an internal pressure of 250 kPa, and subjected to indoor evaluation under the condition of applying a load of 6 kN. The results are shown as an index with the test tire of Conventional Example 1 as 100. The higher the number, the better the result.
These results are also shown in the table below.

＊１）内側補強層のタイヤ半径方向外側端部の高さである。
＊２）内側補強層のタイヤ半径方向内側端部の高さである。
＊３）外側補強層のタイヤ半径方向外側端部の高さである。
＊４）外側補強層のタイヤ半径方向内側端部の高さである。

* 1) The height of the outer end of the inner reinforcing layer in the tire radial direction.
* 2) The height of the inner end of the inner reinforcing layer in the tire radial direction.
* 3) The height of the outer end of the outer reinforcing layer in the tire radial direction.
* 4) The height of the inner end of the outer reinforcing layer in the tire radial direction.

  As shown in the above table, in the test tire of each example in which the organic fiber reinforcing layer and the metal reinforcing layer are arranged under predetermined conditions between the carcass main body part and the folded part of the sidewall part, as shown in the above table. It is clear that lateral rigidity is improved and steering stability is improved while suppressing an increase in tire mass and a decrease in durability.

DESCRIPTION OF SYMBOLS 1 Bead core 2 Carcass ply 2A Main body part 2B Folding part 3 Organic fiber reinforcement layer 4 Metal reinforcement layer 5 Bead filler 6 Hard rubber sheet 7 Belt layer 8 Rim guard 11 Tread part 12 Side wall part 13 Bead part 21 Steel reinforcement layer 22 Fiber reinforcement layer

Claims (4)

A main body portion having a tread portion and a pair of sidewall portions and bead portions connected to both ends in the tire width direction of the tread portion, and extending in a toroidal shape between a pair of bead cores respectively embedded in the pair of bead portions In a pneumatic radial tire having a carcass made of one or more carcass plies formed of a folded portion folded around the bead core,
An organic fiber reinforcing layer adjacent to the outer side in the tire width direction of the carcass main body portion and an inner side in the tire width direction of the carcass folding portion between the carcass main body portion and the turned back portion of the sidewall portion. A metal reinforcing layer that is formed, and an outer end portion in the tire radial direction of the organic fiber reinforcing layer is located on the outer side in the tire radial direction from the tire maximum width position, and is present at a height of 50 to 80% of a tire cross-section height. The outer end portion in the tire radial direction of the metal reinforcing layer is present on the inner side in the tire radial direction from the tire maximum width position, and the organic fiber reinforcing layer and the metal reinforcing layer are in contact with each other in the tire radial direction, or A pneumatic radial tire characterized by being arranged to have an overlap portion.   The pneumatic radial tire according to claim 1, wherein the organic fiber reinforcing layer and the metal reinforcing layer are separated from each other in the tire width direction in the overlap portion.   The pneumatic radial tire according to claim 1 or 2, wherein a length x of the overlap portion is 25 mm or less.   The hard rubber harder than the coating rubber of the organic fiber reinforcing layer and the metal reinforcing layer is disposed between the organic fiber reinforcing layer and the metal reinforcing layer in the overlap portion. The pneumatic radial tire according to any one of claims.

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