JP2008222072A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire reconciled in ensuring the durability of a reinforcing layer, and improving the stability of a vehicle while suppressing the deterioration of ride comfort, especially a pneumatic tire for a heavy load suitably used for a construction vehicle and the like. <P>SOLUTION: The pneumatic tire comprises a carcass 2 composed of a main body 2A extending in a toroidal shape between bead cores, and a folded portion 2B formed continuously with the body folded around the bead core; and a belt 3 disposed on a tire radial direction outer side. On the tire axial direction outer side of the main body 2A of the carcass, an outer side reinforcing layer 4 is formed along the main body from a position of 42 to 48% of a tire cross section height SH to a position of 10 to 16% of the tire cross section height SH. At the tire axial direction inner side of the main body 2A of the carcass, an inner side reinforcing layer 5 is formed along the main body from a position of 58 to 64% of the tire cross section height SH to a position of 39 to 45% of the tire cross section height SH. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire (hereinafter also simply referred to as “tire”), and more particularly to a heavy duty pneumatic tire used in construction vehicles and the like.

  Conventionally, in the case of pneumatic radial tires for heavy loads used in construction vehicles, for example, during work such as lifting and lowering the load when moving to a construction vehicle or moving, problems such as shaking of the vehicle have occurred, and workability There was a problem of getting worse.

On the other hand, by providing a reinforcing layer outside the carcass forming the skeleton of the tire, the front and rear springs of the tire are increased to improve the stability of the vehicle. For example, Patent Document 1 discloses a carcass. By providing predetermined reinforcing layers on the tire axial direction outer side and tire radial direction inner side, the vehicle stability is improved without reducing ride comfort when used on construction vehicles. A pneumatic tire is disclosed.
JP 2005-313764 A (Claims etc.)

  However, in a tire having a structure in which a reinforcing layer is disposed outside the carcass as in the prior art, the cord of the reinforcing layer is formed in a so-called flex zone (a circled portion in FIG. 3) corresponding to the upper part of the folded carcass ply end. There was a case where a part was broken and a failure occurred, which was a problem.

  Accordingly, an object of the present invention is to suitably use a pneumatic tire, in particular, a construction vehicle or the like, in which the durability of the reinforcing layer is ensured and the stability of the vehicle is improved while suppressing deterioration in ride comfort. An object of the present invention is to provide a heavy duty pneumatic tire.

As a result of intensive studies, the present inventors have found the following.
That is, by arranging the reinforcing layer on the side wall portion of the carcass, the front and rear springs of the tire are improved, but the effect is greater when the reinforcing layer is disposed outside the carcass than when the reinforcing layer is disposed inside. large. From this point of view, as described above, a structure in which a reinforcing layer is disposed outside the carcass has been proposed as described above. In this case, the cord of the reinforcing layer is broken in the flex zone (above the end of the folded carcass ply). This leads to a problem of failure.

  From the above viewpoint, as a result of intensive studies, the present inventor can reduce the strain applied to the cord of the reinforcing layer by disposing the reinforcing layer in the flex zone inside the carcass, thereby causing the cord to break. It has been found that the durability of the reinforcing layer can be improved by preventing it, and the present invention has been completed. Here, the magnitude of contribution to the tire rigidity at the position where the reinforcing layer A is arranged is (1) bead portion (FIG. 5A, 13% increase in front and rear rigidity), (2) side portion (FIG. 5B, front and rear). (3) Increased rigidity (8%), (3) Buttress part (Fig. 5 (c), front and rear rigidity increased by 4%) in this order, change the reinforcement layer of the side part to buttress part corresponding to the flex zone from outside to inside The down of the tire front and rear springs is small. Therefore, in the present invention, the stability of the vehicle is not impaired.

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 A pneumatic tire comprising: at least one layer of a carcass formed continuously from the bead core and folded around the bead core; and at least one layer of a belt disposed on the outer side in the tire radial direction of the carcass. In
On the outer side in the tire axial direction of the main body portion of the carcass, at least one outer side reinforcing layer from the position of 42 to 48% of the tire cross section height to the position of 10 to 16% of the tire cross section height along the main body section. Is disposed,
On the inner side in the tire axial direction of the main body portion of the carcass, at least one inner side reinforcing layer from the position of 58 to 64% of the tire cross section height to the position of 39 to 45% of the tire cross section height along the main body section. Is provided.

  In the tire of the present invention, the inner side reinforcing layer and the outer side reinforcing layer preferably overlap each other by 5 mm or more. The cord strength of the cords constituting the inner side reinforcing layer and the outer side reinforcing layer is preferably 100 N or more. Furthermore, the inclination angle of the cords constituting the inner side reinforcing layer and the outer side reinforcing layer is preferably within a range of 20 to 60 ° with respect to the tire radial direction. Furthermore, in the present invention, it is preferable that the cut ends of the cords constituting the inner side reinforcing layer and the outer side reinforcing layer are covered with a cover rubber.

  Furthermore, in the tire of the present invention, from the position overlapping the outer side reinforcing layer by at least 5 mm along the main body portion in the tire axial direction inside the main body portion of the carcass to a position below the bottom surface of the bead core. Preferably, at least one nylon chafer is disposed, and the cord strength of the cord constituting the nylon chafer is preferably 100 N or more, and the inclination angle of the cord constituting the nylon chafer is Preferably, it is in the range of 20 to 60 ° with respect to the tire radial direction.

  According to the present invention, by adopting the above-described configuration, it is possible to realize a pneumatic tire that achieves both the durability of the reinforcing layer and the improvement of the stability of the vehicle while suppressing deterioration in ride comfort. It has become possible. The pneumatic tire of the present invention is particularly suitable as a heavy duty pneumatic tire used for construction vehicles and the like.

Hereinafter, preferred embodiments of the present invention will be described in detail.
In FIG. 1, the fragmentary sectional view of the pneumatic tire which concerns on one suitable embodiment of this invention is shown. As shown in the drawing, 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 toroid shape between the bead cores 1. , A carcass 2 including a folded portion 2B provided continuously from the main body portion 2A and folded around the bead core 1, and a belt 3 disposed on the outer side in the tire radial direction.

In the present invention, the outer side reinforcing layer 4 is disposed along the main body portion 2A on the outer side in the tire axial direction of the main body portion 2A of the carcass. Outer side reinforcing layer 4 is from 42 to 48% of the position of the tire section height SH (the section height indicated by reference character _{H a} in the drawing), 10 to 16% of the position of the tire section height SH (in Fig. It is necessary to dispose in a region up to (the cross-sectional height indicated by the symbol _Hb ). When the reinforcing range is wider, the front and rear springs of the tire are improved. However, when the reinforcing layer comes into contact with the bead core 1, there is a concern that the cord breaks due to the friction of the contact portion, so the lower end of the outer side reinforcing layer 4 is in contact with the bead core 1. It is a position that avoids. Here, the tire cross-section height SH means ½ of the difference between the outer diameter of the tire that is mounted on the applied rim and filled with a prescribed air pressure to make it unloaded and the rim diameter. The applicable rim means a rim defined in the following standard, and the prescribed air pressure means an air pressure defined in accordance with the maximum load capacity in the following standard. Furthermore, the standard is defined by an industrial standard effective in the region where the tire is produced or used, for example, “The Tire and Rim Association Inc. Year Book” in the United States, and “The European Tire and Rim” in Europe. It is “Standards Manual” of Technical Organization, and “JATMA Year book” of Japan Automobile Tire Association in Japan.

Moreover, in this invention, the inner side reinforcement layer 5 is arrange | positioned along the main-body part 2a inside the tire axial direction inner side of the main-body part 2A of the carcass 2. As shown in FIG. The inner side reinforcing layers 5, 39 to 45% of the positions 58 to 64% position from the (cross-sectional height indicated by a symbol _{H c} in the drawing) of the tire section height SH of the tire section height SH (reference numeral in FIG. it is necessary to dispose cross to the height) indicated by H _d. When the upper end position of the inner side reinforcing layer 5 is higher than the above range, the vertical spring becomes too high and the riding comfort is deteriorated. Moreover, it is not necessary to make the lower end position lower than the above range and make the overlap between the inner side reinforcing layer and the outer side reinforcing layer too large. Even when the reinforcing layer is disposed on the hump portion 14, the front and rear springs of the tire are raised, but the longitudinal spring becomes large and deteriorates the ride comfort. Therefore, the reinforcing layer is disposed at a position avoiding the hump portion.

  As shown in the figure, the inner side reinforcing layer 4 and the outer side reinforcing layer 5 are preferably disposed so as to overlap each other, and the distance h of the overlapping region is preferably 5 mm or more, more preferably 10 to 15 mm.

  Each of the outer side reinforcing layer 4 and the inner side reinforcing layer 5 is made of a composite of a cord and rubber. Examples of the cord include steel cord, polyamide (nylon (registered trademark)), and aramid fiber (Kevlar ( Organic fiber cords such as (registered trademark)), and nylon can be preferably used. 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 4a constituting the outer side reinforcing layer 4 is preferably inclined with respect to the tire radial direction, and the inclination angle α is preferably 20 with respect to the tire radial direction. Within a range of ~ 60 °. The cord strength is preferably 100 N or more, and more preferably 200 to 300 N.

  Although not shown, the cord constituting the inner side reinforcing layer 5 is preferably inclined with respect to the tire radial direction as in the case of the outer side reinforcing layer 4, and the inclination angle is preferably the tire. Within a range of 20 to 60 ° with respect to the radial direction. The cord strength is preferably 100 N or more, and more preferably 200 to 300 N.

  By arranging the outer side reinforcing layer 4 and the inner side reinforcing layer 5 satisfying the above conditions in the predetermined region, the effect of the present invention can be obtained more favorably.

  In the present invention, each of the outer side reinforcing layer 4 and the inner side reinforcing layer 5 is one layer in the illustrated example, but may be arranged in two or more layers, and is not particularly limited. In addition, when the outer side reinforcing layer 4 and the inner side reinforcing layer 5 are both provided in a plurality of layers, a greater effect can be obtained by crossing each other.

  In the present invention, the cut ends of the cords constituting the inner side reinforcing layer 4 and the outer side reinforcing layer 5 are preferably covered with cover rubber, and preferably each rubber constituting each reinforcing layer. Cover with the same kind of rubber. By covering the upper and lower ends of the inner side reinforcing layer 4 and the outer side reinforcing layer 5 with the cover rubber, it is possible to effectively prevent the occurrence of a separation failure due to the ends of the reinforcing layers.

Furthermore, in the present invention, in particular, the inclination directions of the cords constituting the outer side reinforcing layer 4 and the inner side reinforcing layer 5 are preferably the same, and the outer side reinforcing layer 4 and the inner side reinforcing layer 5 are configured. It is also preferable that the code strengths of the codes are 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 outer side reinforcing layer 4 and the inner side reinforcing layer 5 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. .

  In the pneumatic tire of the present invention, it is only necessary to satisfy the above conditions with respect to the outer side reinforcing layer 4 and the inner side reinforcing layer 5, and thereby the desired effect of the present invention can be obtained. The tire structure, material, etc. may be appropriately configured according to conventional methods, and are not particularly limited.

  In the present invention, as shown in the figure, a nylon chafer 7 is disposed along the main body 2A on the inner side in the tire axial direction of the main body 2A of the carcass. By arranging the nylon chafer 7, the effect of increasing the front and rear springs can be obtained. The nylon chafer 7 is preferably disposed from a position overlapping at least 5 mm with the outer side reinforcing layer 4 to a position below the bottom surface of the bead core 1 (the cross-sectional height indicated by X in the drawing). The cord constituting the nylon chafer 7 is also preferably inclined with respect to the tire radial direction as in the case of the reinforcing layers 4 and 5, and the inclination angle is preferably 20 with respect to the tire radial direction. Within a range of ~ 60 °. The cord strength is preferably 100 N or more, and more preferably 200 to 300 N.

  Further, for example, the carcass 2 extends from the crown portion 12 through the sidewall portion 13 to the bead portion 11 and reinforces each of these portions, and the end of the folded portion has a tire cross-section height SH of 40. It is preferable to be located within a range of ˜60%. The carcass 2 is provided in one layer in the illustrated example, but may be provided in two or more layers, and is not particularly limited. Further, the belt 3 is provided in at least one layer, in the illustrated example, four layers on the outer side in the radial direction of the crown portion of the carcass 2. Further, a tread 6 formed in an annular shape with a rubber material and installed on the road surface is disposed on the crown portion 12, and a tread pattern is appropriately formed on the surface of the tread 6. Furthermore, an inner liner (not shown) is disposed in the innermost layer of the tire.

  The pneumatic tire of the present invention is particularly suitable as a heavy-duty pneumatic radial tire used for construction vehicles, construction machines and the like.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Example>
As shown in FIG. 3, a main body 2 </ b> A that is folded back from the inside to the outside around the bead cores 1 embedded in the pair of bead parts 11 and extends in a toroid shape between the bead cores 1, A pneumatic structure comprising: a folded portion 2B continuously provided and folded around the bead core 1; a one-layer steel radial carcass 2; and a four-layer steel belt 3 disposed on the outer side in the tire radial direction. In the tire, the outer side reinforcing layer 24 and the inner side reinforcing layer 25 are disposed on the outer side and the inner side in the tire axial direction of the main body 2A of the carcass under the conditions according to the following Table 1, respectively. Produced. Further, on the inner side in the tire axial direction of the main body 2A of the carcass, a single nylon chafer 27 was disposed along the main body under the conditions according to Table 1 below.

<Conventional example 1>
A pneumatic tire of Conventional Example 1 was manufactured (not shown) in the same manner as Example 1 except that the outer side reinforcing layer and the inner side reinforcing layer were not provided.

<Conventional example 2>
As shown in FIG. 4, in the same manner as in Example 1, except that only the outer side reinforcing layer 34 was provided as the reinforcing layer, the pneumatic condition of Conventional Example 2 was changed according to the conditions shown in Table 1 below. A tire was produced. Further, on the inner side in the tire axial direction of the main body 2A of the carcass, one nylon chafer 37 was disposed along the main body under the conditions according to Table 1 below.

<Drum durability test>
Drum durability tests were carried out under the conditions of a camber angle of 0 ° and a slip angle of 0 ° with an internal pressure of 500 kPa filled in the test tires of the examples and conventional examples, with a load of 18.2 tons. The tire size was 23.5R25.

  As a result, cord breakage occurred in the test tire of Conventional Example 2 in 44 hours, whereas cord breakage did not occur in the test tire of the example even in 73 hours. In the test tire of Conventional Example 1, a bead failure occurred in 74 hours.

<Rigidity evaluation>
The longitudinal rigidity was evaluated for the test tires of the examples and the conventional examples. As a result, the test tire of the example has a front-rear rigidity that is 20% higher than that of the test tire of the conventional example 1 in which no reinforcing layer is provided, and the test tire of the conventional example 2 having the conventional reinforcing structure (conventional example) It was confirmed that the same rigidity as that of No. 1 test tire was obtained by 23%.

<Stability and ride evaluation>
With respect to the test tires of the examples and the conventional examples, the stability and riding comfort when the vehicle was mounted were evaluated by an actual vehicle feeling test. All the results were evaluated with a score of 5 points. The higher the number, the better. As a result, as shown in Table 2 below, the test tires of the examples are more stable than the test tires of the conventional example 1 without the reinforcing layer, and the present invention has a conventional reinforcing structure. It was confirmed that excellent stability comparable to that of the test tire of Conventional Example 2 was obtained. In addition, the test tires of the examples have the same level of riding comfort as the conventional examples 1 and 2, and it was confirmed that the riding comfort is not impaired by the present invention.

  From the above evaluation results, it is clear that in the test tires of the examples, the stability of the vehicle can be improved while suppressing the deterioration of the riding comfort and ensuring the durability of the reinforcing layer.

1 is a partial cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. It is explanatory drawing which shows the inclination angle of the code | cord | chord which comprises an outer side reinforcement layer. 1 is a partial cross-sectional view showing a pneumatic tire according to Example 1. FIG. It is a fragmentary sectional view which shows the pneumatic tire which concerns on the prior art example 2. It is explanatory drawing which shows the case where a reinforcement layer is each arrange | positioned to (a) bead part, (b) side part, and (c) buttress part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bead core 2 Carcass 2A Main-body part 2B Fold-up part 3 Belts 4, 24, 34 Outer side reinforcement layer 5, 25, 35 Inner side reinforcement layer 6 Tread 7 Nylon chafer 11 Bead part 12 Crown part 13 Side wall part

Claims (8)

A bead core embedded in each of the pair of bead parts is folded back and locked from the inside to the outside, and a main body part extending in a toroidal shape between the bead cores, and continuously provided around the main body part around the bead core In a pneumatic tire comprising: a folded portion folded back into at least one layer of a carcass; and at least one layer of a belt disposed on the outer side in the tire radial direction of the carcass,
On the outer side in the tire axial direction of the main body portion of the carcass, at least one outer side reinforcing layer from the position of 42 to 48% of the tire cross section height to the position of 10 to 16% of the tire cross section height along the main body section. Is disposed,
On the inner side in the tire axial direction of the main body portion of the carcass, at least one inner side reinforcing layer from the position of 58 to 64% of the tire cross section height to the position of 39 to 45% of the tire cross section height along the main body section. A pneumatic tire characterized in that is provided.   The pneumatic tire according to claim 1, wherein the inner side reinforcing layer and the outer side reinforcing layer overlap each other by 5 mm or more.   The pneumatic tire according to claim 1 or 2, wherein cord strength of cords constituting the inner side reinforcing layer and the outer side reinforcing layer is 100 N or more.   The pneumatic tire according to any one of claims 1 to 3, wherein an inclination angle of a cord constituting the inner side reinforcing layer and the outer side reinforcing layer is in a range of 20 to 60 ° with respect to a tire radial direction.   The pneumatic tire according to any one of claims 1 to 4, wherein a cut end of a cord constituting the inner side reinforcing layer and the outer side reinforcing layer is covered with a cover rubber.   At least one nylon chafer is disposed on the inner side in the tire axial direction of the main body portion of the carcass, along the main body portion, from a position overlapping at least 5 mm with the outer side reinforcing layer to a position below the bottom surface of the bead core. The pneumatic tire according to any one of claims 1 to 5.   The pneumatic tire according to claim 6, wherein a cord strength of a cord constituting the nylon chafer is 100 N or more.   The pneumatic tire according to claim 6 or 7, wherein an inclination angle of a cord constituting the nylon chafer is in a range of 20 to 60 ° with respect to a tire radial direction.

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