JP2005313764A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire improving vehicle stability without deteriorating riding comfort when mounted and used in a construction vehicle or the like. <P>SOLUTION: The pneumatic tire has a carcass 2 which is folded back from the inside to the outside around bead cores 1 respectively embedded in a pair of beads 11, is engaged therewith and comprises a main body portion 2A extending in a toroid shape between the bead cores 1 and fold-back portions 2B formed continuously to the main body portion 2A and folded back around the bead cores 1. A main reinforcing layer 3 is arranged on an outer side in a tire axial direction of the main body portion 2A of the carcass 2 from a position of 58-64% of a tire sectional height SH to a position of 14-22% of the tire sectional height SH along the main body portion 2A. An auxiliary reinforcing layer 4 is arranged on an inner side in a tire radial direction of the carcass 2 at least from an inner end in the tire radial direction of the main reinforcing layer 3 to inner ends in the tire radial direction of the bead cores 1 along the carcass 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire (hereinafter also simply referred to as “tire”), and more particularly to a heavy-duty pneumatic radial tire mounted on a construction vehicle or the like.

  Conventionally, in heavy-duty pneumatic radial tires, for example, during work such as lifting and lowering the load when moving to a construction vehicle, movement, etc., stability problems such as shaking occur, and workability deteriorates. There was a problem.

  On the other hand, as conventional knowledge, in order to improve the stability of the vehicle, it is effective to increase the rigidity of the tire (longitudinal spring, lateral spring, front and rear spring, etc.) by appropriately reinforcing the location. I know. However, if the vertical spring is raised too much, road surface irregularities cannot be absorbed, and another problem arises that ride comfort deteriorates.

  As a technique related to side part reinforcement, for example, Patent Document 1 discloses a pneumatic radial tire having two or more carcass plies and a belt reinforcing layer in a tread portion, and one or more carcass plies are disposed inside a bead wire. The other one or more carcass plies are arranged so as to cover the winding end of the carcass ply, and are sandwiched between the carcass plies so as to be 40 ° to 90 ° with respect to the circumferential direction. One or more side reinforcing layers made of organic fiber cords having an angle are arranged, and one end of the side reinforcing layer is fixed near the bead wire, and the other end is inserted under the belt reinforcing layer. A fixed pneumatic radial tire is described.

Patent Document 2 discloses that a terminal portion of at least one carcass ply made of a rubberized layer of a radial or semi-radial arrayed metal cord is wound around a bead core, and a carcass main portion formed by the carcass and a winding end. A rubber stock extending radially outward of the tire from the bottom end adjacent to the bead core is disposed between and a reinforcing layer made of a highly elastic cord on the outer side of the winding end, and the carcass main part And an auxiliary layer disposed adjacent to the inner surface of the rubber stock, the auxiliary layer having a lower end located in the vicinity of the bottom of the bead and having an upper end height equal to the height of the winding end or A heavy vehicle radial tire is described which is a highly elastic cord ply arranged to exceed the upper end height of the reinforcing layer.
Japanese Patent Laid-Open No. 62-4615 JP 59-190011 A

  Various studies have been made so far regarding the compatibility between the above-mentioned vehicle stability and ride comfort, but it is still not sufficient. It has been desired to realize a tire that can be improved.

  Accordingly, an object of the present invention is to provide a pneumatic tire capable of improving the stability of a vehicle without reducing the ride comfort when used on a construction vehicle or the like by appropriately increasing the rigidity of the tire. It is to provide.

  As a result of intensive studies, the inventor has arranged a reinforcing layer in a region from the outside in the axial direction of the carcass main body portion to the inner end portion in the tire radial direction of the bead core, so that the longitudinal spring is not raised too much and It has been found that it is possible to improve both the stability and the ride comfort by increasing the tire rigidity. However, when the reinforcing layer is provided continuously in the above region, particularly when the bead core has a hexagonal shape, there is a concern that the cord of the reinforcing layer may be broken between the bead core and the carcass main body. Therefore, the reinforcing layer is divided, and the divided reinforcing layer is arranged outside the carcass folding portion, which can improve the vehicle stability without impairing the ride comfort, and further The present inventors have found that other problems such as these do not occur and have completed the present invention.

That is, the pneumatic tire of the present invention includes a main body portion that is folded back from the inside to the outside around a bead core embedded in a pair of bead portions and extends in a toroid shape between the bead cores, and the main body portion. In a pneumatic tire provided with a carcass comprising a folded portion continuously provided and folded around the bead core,
A main reinforcing layer is disposed on the outer side in the tire axial direction of the main body portion of the carcass from a position of 58 to 64% of the tire cross section height to a position of 14 to 22% of the tire cross section height along the main body section. And
A sub-reinforcing layer is disposed on the inner side in the tire radial direction of the carcass from at least the inner radial end of the main reinforcing layer to the inner radial end of the bead core along the carcass. It is characterized by.

  In the present invention, the cords constituting the main reinforcing layer and the sub reinforcing layer are preferably inclined with respect to the tire radial direction, and the inclination angle is preferably 20 to 60 ° with respect to the tire radial direction. Is within the range. Moreover, it is also preferable that the inclination directions of the cords constituting the main reinforcing layer and the sub reinforcing layer are the same.

  Further, the cord strength of the cords constituting the main reinforcement layer and the sub-reinforcement layer is preferably 200 N or more, and the cord strengths of the cords constituting the main reinforcement layer and the sub-reinforcement layer are substantially the same. preferable. Furthermore, the bead core is preferably hexagonal.

  Furthermore, it is preferable that an end of the folded portion of the carcass is located within a range of 40 to 60% of the tire cross-sectional height, and the main reinforcing layer and the sub reinforcing layer overlap each other by 5 mm or more. preferable. Furthermore, it is also preferable that the cut end of the cord constituting the main reinforcing layer is covered with the same rubber as the rubber constituting the main reinforcing layer.

  According to the present invention, by adopting the above-described configuration, it is possible to suppress the deformation of the carcass ply by the main reinforcing layer and obtain an effect of improving the tire rigidity, and to suppress the circumferential displacement of the ply from the bead portion. Thus, the displacement amount in the ply circumferential direction of the hump portion and the tread portion can be significantly suppressed. Further, by arranging the sub-reinforcing layer together with the main reinforcing layer, it is possible to more reliably suppress ply deformation from the bead portion, and the effect obtained by the main reinforcing layer can be further enhanced. Therefore, by these synergistic effects, it is possible to realize a pneumatic tire that can improve the stability of the vehicle without reducing the ride comfort.

  In Patent Document 2 described above, a reinforcing layer made of a highly elastic cord is disposed outside the winding end of the carcass ply, and an auxiliary layer disposed adjacent to the inner surface of the carcass main body is provided. Although a radial tire for heavy vehicles is described, the auxiliary layer is arranged such that the upper end of the auxiliary layer exceeds the height of the rolled-up end or the upper end of the reinforcing layer. Is different from the auxiliary reinforcing layer according to the present invention which is disposed from the inner end of the bead core in the tire radial direction. That is, the technology described in Patent Document 2 defines the positions of both the reinforcing layer and the auxiliary layer for the purpose of realizing a tire that can improve the durability of the bead portion and can regenerate the tread several times. On the other hand, in the present invention, for the purpose of achieving both vehicle stability and ride comfort, the arrangement positions of the main reinforcing layer and the sub reinforcing layer are defined in a predetermined manner. It differs from the invention in terms of its main configuration, problems, and effects obtained.

Hereinafter, preferred embodiments of the present invention will be described in detail.
In FIG. 1, the fragmentary sectional view of the pneumatic tire of one suitable example of this invention is shown. As shown in the figure, the tire of the present invention includes a main body 2A that is folded back from the inside to the outside around a bead core 1 embedded in a pair of bead portions 11 and extends in a toroidal shape between the bead cores 1. The carcass 2 includes a folded portion 2B that is provided continuously with the body portion 2A and is folded around the bead core 1. In the illustrated example, the carcass 2 is provided in one layer, but it may be provided in two or more layers, and is not particularly limited.

  In the present invention, the main reinforcing layer 3 is disposed along the main body portion 2A outside the carcass main body portion 2A in the tire axial direction. The main reinforcing layer 3 is positioned from 58 to 64% of the tire cross-section height SH (cross-section height indicated by Ha in the drawing) to 14 to 22% of the tire cross-section height SH (reference Hb in the drawing). It is necessary to dispose in a region up to (the cross-sectional height shown in FIG. Here, the tire cross-section height SH means 1/2 of the difference between the outer diameter of the tire and the rim diameter. The reason why the main reinforcing layer 3 is disposed in such a region is as follows.

  That is, when an input in the front-rear direction is applied to the tire, the circumferential displacement amount of the carcass ply gradually increases toward the hump portion 13 and the tread portion 14 by integrating the displacement amount from the bead portion. In the present invention, by disposing the main reinforcing layer 3 within the specific range from the side closer to the bead part 11 to the side part 12, the circumferential displacement of the ply from the bead part 11 can be suppressed. The displacement amount in the ply circumferential direction of the hump portion 13 and the tread portion 14 can be significantly suppressed. Thereby, the rigidity of the front-back direction improves. In addition, even when the main reinforcing layer is inserted in the hump portion 13, the tire rigidity is increased. However, in this case, the longitudinal spring becomes higher and the riding comfort is lowered, which is not appropriate.

  The main reinforcing layer 3 is composed of a composite of cord and rubber. Examples of the cord include steel cord, and organic fiber cord such as polyamide (nylon (registered trademark)) and aramid fiber (Kevlar (registered trademark)). Can be mentioned. Examples of rubber include acrylonitrile-butadiene copolymer rubber (NBR), acrylonitrile-styrene-butadiene copolymer rubber (NSBR), styrene butadiene rubber (SBR), butadiene rubber (BR), and natural rubber (NR). Isoprene rubber (IR), styrene isoprene rubber (SIR), styrene isoprene butadiene rubber (SIBR), butyl rubber (IIR), halogenated butyl rubber (Hal-IIR) and the like can be used.

  As shown in FIG. 2, the cord 3a constituting the main reinforcing layer 3 is preferably inclined with respect to the tire radial direction, and the inclination angle α is preferably 20 to 60 ° with respect to the tire radial direction. Within the range of The cord strength is preferably 200 N or more. By disposing the main reinforcing layer 3 that satisfies such conditions in the predetermined region, the effect of suppressing ply deformation according to the present invention can be obtained more favorably, and the rigidity of the tire can be improved.

  Further, the cut end of the cord 3 a constituting the main reinforcing layer 3 is preferably covered with the same rubber as that constituting the main reinforcing layer 3. By covering both ends of the main reinforcing layer 3 with cover rubber, it becomes possible to effectively prevent the occurrence of a separation failure due to the end of the main reinforcing layer 3.

  In the present invention, the auxiliary reinforcing layer 4 is disposed along the carcass 2 on the inner side in the tire radial direction of the carcass 2. The sub-reinforcing layer 4 needs to be disposed at least from the inner radial end of the main reinforcing layer 3 to the inner radial end of the bead core 1, and preferably, as shown in FIG. It is disposed so as to overlap with the region where the main reinforcing layer 3 is disposed. The distance h of the overlap region is preferably 5 mm or more.

  The sub-reinforcing layer 4 is composed of a composite of a cord and rubber, and as the cord and rubber, those similar to those described above for the main reinforcing layer 3 can be appropriately selected and used. Preferably, the auxiliary reinforcing layer 4 using a nylon cord is used.

  Although not shown, the cord constituting the auxiliary reinforcing layer 4 is also preferably inclined with respect to the tire radial direction as in the case of the main reinforcing layer 3, and the inclination angle is preferably the tire radius. It is set within a range of 20 to 60 ° with respect to the direction. The cord strength is preferably 200 N or more. By using the sub-reinforcing layer 4 satisfying such conditions in the predetermined region and using it together with the main reinforcing layer 3, it becomes possible to more strongly suppress ply deformation from the bead portion, and the effects of the present invention can be further enhanced. Can be increased.

  In the present invention, in particular, the inclination directions of the cords constituting the main reinforcing layer 3 and the sub reinforcing layer 4 are preferably the same, and the cord strength of the cords constituting the main reinforcing layer 3 and the sub reinforcing layer 4 is preferably the same. Are also preferably substantially the same. Here, “substantially the same” means that the error in code strength is within a range of ± 20%. Therefore, it can be said that the main reinforcing layer 3 and the sub reinforcing layer 4 are preferably prepared by embedding the same type of cords at the same inclination angle so that the inclination directions of the cords are the same. Note that at least one of the main reinforcing layer 3 and the auxiliary reinforcing layer 4 needs to be provided, but two or more may be provided, and there is no particular limitation.

  In the pneumatic tire of the present invention, it is only necessary to satisfy the above-mentioned requirements with respect to the main reinforcing layer 3 and the sub reinforcing layer 4, and thereby the desired effect of the present invention can be obtained. What is necessary is just to comprise suitably according to a conventional method about a structure, a material, etc., and it does not restrict | limit in particular.

  For example, a tread 5 formed in an annular shape by a rubber material and installed on a road surface is disposed on the crown portion 14 of the tire of the present invention, and a tread pattern is appropriately formed on the tread 5. Further, between the carcass 2 and the tread 5, at least one belt layer 6 in the illustrated example is disposed, and an inner liner (not shown) is formed in the innermost layer of the tire. Further, although not particularly limited, in the present invention, it is preferable that the end of the folded portion of the carcass 2 is located within a range of 40 to 60% of the tire cross-section height SH, thereby further increasing the tire rigidity. Can contribute to the improvement.

  In the present invention, since the reinforcing layer is divided into the main reinforcing layer 3 and the sub reinforcing layer 4, even when the bead core 1 has a hexagonal shape, problems such as cord breakage of the reinforcing layer do not occur. There is a merit. The pneumatic tire of the present invention is particularly suitable as a heavy-duty pneumatic radial tire for construction vehicles and the like.

Hereinafter, the present invention will be described specifically by way of examples.
Test tires having the structure shown in FIG. 1 were produced under the conditions shown in Table 1 below. The tire size was 20.5R25. For comparison, a test tire of a conventional example in which only the auxiliary reinforcing layer was provided was also produced.

＊１、＊２）タイヤ断面高さＳＨの何％の位置であるかを意味する。

* 1, * 2) It means what percentage of the tire cross-section height SH.

  The test tires of the examples and the conventional examples were mounted on an actual vehicle, and the stability performance and the riding comfort performance were evaluated by a feeling test. The feeling test has a 10-point scale, with 10 being good. The results are shown in Table 2 below.

  As can be seen from the results of Table 2 above, in the tires of the respective examples provided with the main reinforcing layer and the sub reinforcing layer according to the present invention, the vehicle comfort is hardly impaired as compared with the conventional example. Stability could be improved.

It is a fragmentary sectional view of the pneumatic tire concerning one suitable embodiment of the present invention. It is explanatory drawing which shows the inclination | tilt angle of the code | cord | chord which comprises a main reinforcement layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bead core 2 Carcass 2A Main part 2B Folding part 3 Main reinforcement layer 3a Cord 4 Sub reinforcement layer 5 Tread 6 Belt layer 11 Bead part 12 Side part 13 Hump part 14 Crown part

Claims (10)

A bead core embedded in each of a pair of bead portions is folded back and locked from the inside to the outside, and a main body portion extending in a toroid shape between the bead cores, and continuously provided around the main body portion and around the bead core In a pneumatic tire provided with a carcass composed of a folded portion folded back into
A main reinforcing layer is disposed on the outer side in the tire axial direction of the main body portion of the carcass from a position of 58 to 64% of the tire cross section height to a position of 14 to 22% of the tire cross section height along the main body section. And
A sub-reinforcing layer is disposed on the inner side in the tire radial direction of the carcass from the inner end in the tire radial direction of the main reinforcing layer to the inner end in the tire radial direction of the bead core along the carcass. Pneumatic tire characterized by.   The pneumatic tire according to claim 1, wherein cords constituting the main reinforcing layer and the sub reinforcing layer are inclined with respect to the tire radial direction.   The pneumatic tire according to claim 2, wherein an inclination angle of the cord is in a range of 20 to 60 degrees with respect to a tire radial direction.   The pneumatic tire according to claim 2 or 3, wherein the inclination directions of the cords constituting the main reinforcing layer and the sub reinforcing layer are the same.   The pneumatic tire according to any one of claims 1 to 4, wherein a cord strength of a cord constituting the main reinforcing layer and the sub reinforcing layer is 200 N or more.   The pneumatic tire according to any one of claims 1 to 5, wherein cord strength of cords constituting the main reinforcing layer and the sub reinforcing layer is substantially the same.   The pneumatic tire according to claim 1, wherein the bead core has a hexagonal shape.   The pneumatic tire according to any one of claims 1 to 7, wherein an end of the folded portion of the carcass is located within a range of 40 to 60% of a tire cross-section height.   The pneumatic tire according to any one of claims 1 to 8, wherein the main reinforcing layer and the sub reinforcing layer overlap each other by 5 mm or more. The pneumatic tire according to any one of claims 1 to 9, wherein a cut end of the cord constituting the main reinforcing layer is covered with the same rubber as the rubber constituting the main reinforcing layer.

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