JP2005081873A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire which can surely suppress the flaking damage of a hollow portion while securing the merits of a hollow structure of a carcass. <P>SOLUTION: The pneumatic radial tire comprises a carcass 6 composed of two carcass plies 6A, 6B, and a belt layer 7 composed of a plurality of belt plies 7A, 7B. At least the carcass ply 6B located on the outside in the radial direction of the tire is composed of a pair of right and left split ply segments 10P which have their one end E1 in the outside axial direction of the tire from the equator C of the tire, and terminate at the other end E2 after elongating in the radially inward direction of the tire from the end E1, and after being folded back around a bead core 5. The end E1 of each split ply segment 10P is sandwiched between the belt plies 7A, 7B. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pneumatic radial tire in which a carcass ply is formed in a hollow shape by a pair of left and right divided ply pieces, and damage at the hollow portion is prevented.

  As schematically shown in FIG. 6, for example, Patent Documents 1 and 2 propose a radial tire in which a carcass ply A is formed in a hollow shape by a pair of left and right divided ply pieces a. This has the advantage that the ride comfort can be enhanced by the hollow portion g, and compatibility with the contradictory steering stability can be achieved.

JP 2000-71714 A JP 2001-260617 A

  However, in the case of such a hollow structure, there is a problem in that when the tire deforms during traveling, the end e facing the split ply pieces a, a is easy to move, and peeling damage is likely to occur starting from the end e. It is difficult to sufficiently suppress the peeling damage even when a conventional carcass ply that is not hollowed is placed inside the carcass ply A in the radial direction.

  Therefore, in the present invention, one of the belt plies is arranged radially inside the hollow carcass ply A, and the end e of the divided ply pieces a, a facing each other between the belt ply and another belt ply is provided. A pneumatic radial tire that can reliably prevent peeling damage from the end e and contribute to further improvement in handling stability while securing the above-described advantages of the hollow structure based on pinching. The purpose is to provide.

In order to achieve the above object, the invention of claim 1 is directed to a carcass comprising two carcass plies folded around a bead core of a bead part from a tread part through a sidewall part, and a plurality of carcass plies arranged in the tread part. A pneumatic radial tire comprising a belt layer composed of a plurality of belt plies,
Of the two carcass plies, at least the radially outer carcass ply has one end on the outer side in the tire axial direction from the tire equator, and extends from the one end to the inner side in the tire radial direction and is folded around the bead core. While consisting of a pair of left and right split ply pieces where the other end is interrupted,
The one end of the split ply piece is sandwiched between the belt plies.

  According to a second aspect of the present invention, one end and the other end of the split ply piece are sandwiched between the belt plies.

According to a third aspect of the present invention, there is provided a belt comprising a carcass composed of a single carcass ply folded around a bead core of a bead portion from a tread portion to a sidewall portion, and a plurality of belt plies disposed in the tread portion. A pneumatic radial tire comprising a layer,
The carcass ply is composed of a pair of left and right split ply pieces having one end on the outer side in the tire axial direction from the tire equator and extending from the one end to the inner side in the tire radial direction, being folded around the bead core and interrupted at the other end. ,
The one end and the other end of the split ply piece are sandwiched between the belt plies.

  Since the present invention is configured as described above, it is possible to achieve both the advantages of the hollow structure, i.e., both ride comfort and handling stability, and reliably suppress peeling damage from the end of the split ply piece. Moreover, it can contribute to further improvement in handling stability.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view illustrating a case where the pneumatic radial tire of the present invention is a passenger tire.

  In FIG. 1, a pneumatic radial tire 1 (hereinafter referred to as a tire 1) is disposed in a tread portion 2, a carcass 6 that is turned around a bead core 5 of a bead portion 4 through a sidewall portion 3 from a tread portion 2. And a tough belt layer 7 to be formed.

  The belt layer 7 is formed of two or more belt plies 7A and 7B in which high-strength belt cords are arranged at an angle of, for example, 10 to 35 ° with respect to the tire circumferential direction. By crossing the plies between each other, the belt rigidity is enhanced, and the substantially entire width of the tread portion 2 is strongly reinforced with a tagging effect. In this example, a steel cord is used as the belt cord, but high modulus organic fiber cords such as polyethylene naphthalate (PEN), polyethylene terephthalate (PET), and aromatic polyamide can be used as necessary.

  Further, in this example, the belt layer 7 has a radially stepped belt ply 7A wider than the outer belt ply 7B, and the outer end position is shifted by about 3 to 10 mm in the tire axial direction so that a rigidity step is generated. It is mitigating.

  Next, the carcass 6 is composed of two carcass plies 6A and 6B in which the carcass cord is arranged at an angle of 70 to 90 degrees with respect to the tire circumferential direction in the tire of the first embodiment. Organic fiber cords such as polyester, rayon and aromatic polyamide are preferably used.

  Of the two carcass plies 6A and 6B, the carcass ply 6B disposed at least radially outward is formed by a discontinuous hollow carcass ply 10 including a pair of left and right divided ply pieces 10P.

  Specifically, the split ply piece 10P has a main portion 10Pa having one end E1 on the outer side in the tire axial direction from the tire equator C and extending from the one end E1 in the tire radial direction to the bead core 5; A folded portion 10Pb that is continuous to 10 Pa and is folded from the inside to the outside in the tire axial direction around the bead core 5 and the other end E2 ends. Accordingly, the pair of split ply pieces 10P form a hollow portion g between the opposite ends E1 and E1.

  At this time, the present invention is characterized in that the one end E1 of the divided ply piece 10P is sandwiched between the belt plies 7A and 7B and is firmly connected to the belt plies 7A and 7B. Accordingly, the movement of the one end E1 can be effectively restrained, and the peeling damage starting from the one end E1 can be reliably suppressed. In addition, the firm connection between the split ply piece 10P and the belt plies 7A and 7B makes it possible to secure a higher tire side rigidity, compared to a conventional hollow structure tire (shown in FIG. 6). Excellent maneuvering stability can be demonstrated.

  Here, in order to securely pinch the one end E1, the pinch is a distance in the tire axial direction from the outer end of the narrow ply (outer belt ply 7B in this example) of the belt plies to the one end E1. Desirably, the width K1 is 1.0 mm or more, preferably 10.0 mm or more, more preferably 20.0 mm or more. If the width K1 is less than 1.0 mm, the connection between the divided ply piece 10P and the belt layer 7 is insufficient. Thus, the effect of suppressing the peeling damage at the one end E1 cannot be exhibited, and the steering stability tends to be reduced. Further, the hollow width W1 in the tire axial direction of the hollow portion g is preferably 30% or more of the tread width TW from the viewpoint of ride comfort.

  In this example, the folded portion 10Pb of the split ply piece 10P is wound up to the tread portion 2, and the other end E2 is also sandwiched between the belt plies 7A and 7B and terminated. In such a case, since the one end E1 and the other end E2 are constrained, further improvement in steering stability is achieved, such as higher tire side rigidity. At this time, the distance in the tire axial direction (nipping width K2) from the outer end of the narrow belt ply to the other end E2 is preferably 1.0 mm or more, similar to the holding width K1, and the one end It is preferable that E1 and the other end E2 are displaced from each other in the tire axial direction by a distance L0 of 1.0 mm or more to reduce the rigidity step. As the positional deviation, it is preferable that the other end E2 is positioned outside the one end E1 in the tire axial direction. However, as schematically shown in FIG. 2 (A), it can be positioned on the inner side in the tire axial direction. In such a case, the distance W2 between the other ends E2 and E2 is the tread as with the hollow width W1. It is preferable to set it to 30% or more of the width TW.

  A bead reinforcement bead apex rubber 8 is provided between the main portion 10Pa and the turn-up portion 10Pb so as to taper outward from the bead core 5 in the radial direction.

  Next, the inner carcass ply 6A, in this example, is turned up at both ends of the body portion 11a straddling the bead cores 5 and 5 continuously from the inner side to the outer side in the tire axial direction around the bead core 5. It is formed by a non-hollow-out carcass ply 11 provided with 11b. The non-centered carcass ply 11 is preferably arranged through the inner side in the radial direction of the inner belt ply 7A as in this example, whereby the one end E1 of the split ply piece 10P and the belt ply 7A, Since 7B is directly contacted and pinched, the connection force of both can be further increased. However, as shown in FIG. 2B, the non-voided carcass ply 11 may be disposed between the hollowed carcass ply 10 and the inner belt ply 7A.

  Further, as the non-centered carcass ply 11, in this example, a case where the folded portion 11 b is terminated at the bead portion 2 or the sidewall portion 3 is illustrated. However, as schematically shown in FIG. 3 (A), the folded portion 11b is wound up to the tread portion 2 similarly to the folded portion 10Pb of the split ply piece 10P, and the outer end E3 is narrowed between the belt plies 7A and 7B. The steering stability can be further improved by such a configuration. At this time, it is preferable that the outer end E3 is displaced in the tire axial direction from the one end E1 and the other end E2 in order to reduce the rigidity step.

  3B, the folded portion 10Pb of the split ply piece 10P is terminated at the bead portion 2 or the sidewall portion 3, and the folded portion 11b of the non-centered carcass ply 11 is connected to the belt ply 7A. , 7B. Further, as schematically shown in FIG. 3C, both the folded portion 10Pb of the split ply piece 10P and the folded portion 11b of the non-centered carcass ply 11 are terminated at the bead portion 2 or the sidewall portion 3. You can also. At this time, in order to prevent damage from the terminal portion, it is preferable that the folded portion 11 extends outward in the radial direction so as to cover the other end E2 of the folded portion 10Pb.

  In the tire according to the first embodiment, the inner and outer carcass plies 6A and 6B can be formed by the hollow carcass ply 10 including a pair of divided ply pieces 10P. At this time, as schematically shown in FIG. 4A, the folded portions 10Pb of the hollow carcass plies 10 are respectively wound up to the tread portion 2, and the other ends E2 are belt plies 7A and 7B in the same manner as the one ends E1. As shown in FIG. 4B, each other end E2 of the folded portion 10Pb is terminated at the bead portion 2 or the sidewall portion 3, or is schematically shown in FIG. As described above, the other end E2 of one folded portion 10Pb can be held between the belt plies 7A and 7B, and the other end E2 of the other folded portion 10Pb can be terminated by the bead portion 2 or the sidewall portion 3. .

  In the case of FIGS. 4A and 4B, the one end E1, E1 and the other end E2, E2 are displaced by the distance L0 in the tire axial direction or the tire radial direction to alleviate the rigidity step. It is preferable to do so.

Next, FIG. 5 illustrates the tire 1 of the second embodiment.
In the second embodiment, the carcass 6 includes a single carcass ply 6C in which carcass cords are arranged at an angle of 70 to 90 degrees with respect to the tire circumferential direction, and the carcass ply 6C includes the pair of split ply pieces. The hollow carcass ply 10 is formed of 10P.

  The hollow carcass ply 10 has one end E1 and the other end E2 sandwiched between the belt plies 7A and 7B, so that the peeling from the one end E1 and the other end E2 due to the hollow part g. Damage can be reliably suppressed, and excellent ride comfort and steering stability can be ensured at the same time.

  As in the case of the first embodiment, the hollow width W1 is preferably 30% or more of the tread width TW, and the holding width K1 is 1.0 mm or more, more preferably 10.0 mm or more. Furthermore, it is preferable to be 20.0 mm or more. Further, it is preferable that the holding width K2 is 1.0 mm or more, and the one end E1 and the other end E2 are displaced by the distance L0 in the tire axial direction. At this time, if the other end E2 is displaced inward in the tire axial direction from the one end E1, the distance between the other ends E2 and E2 is preferably 30% or more of the tread width TW.

  The particularly preferred embodiment of the present invention has been described in detail above. However, the present invention is not limited to the illustrated embodiment. For example, another belt ply may be formed on the outer side of the outer belt ply 7B. In addition to passenger car tires, the present invention can be implemented in various forms such as being formed as various categories of tires such as motorcycles, light trucks, and heavy duty tires.

A tire having a tire size of 185 / 70R14 having the specifications shown in Table 1 was prototyped, and the ride comfort, handling stability, and tread durability of each sample tire were tested and compared. The specifications of the carcass and the belt layer other than those in Table 1 are the same as follows.
Carcass cord: 1100 dtex (PET),
Cord angle: 90 degrees,
Number of cords driven: 38 / 5cm,
・ Belt layer cord: 1 × 3 × 0.27HT (steel),
Cord angle: +20 degrees / -20 degrees
Number of cords driven: 40 / 5cm,

(1) Ride comfort and handling stability;
A sample tire is mounted on all wheels of a vehicle (1600cc passenger car) with a rim (5J × 14) and internal pressure (200kpa), and runs on a dry asphalt tire test course. Riding comfort and handling stability Is indicated by an index with Comparative Example 1 as 100 by sensory evaluation of the driver. A larger index is better.

(2) Tread durability;
Using a drum testing machine, running at a constant speed of 80 km / h under conditions of rim (5J × 14), internal pressure (200 kpa), and load (5.00 kN), and running when damage to the tread occurs The distance is displayed as an index with Comparative Example 1 as 100.

It is sectional drawing which shows one Example of the pneumatic tire of 1st Embodiment of this invention. (A), (B) is sectional drawing which outlines another Example. (A)-(C) are sectional drawings which show still another Example. (A)-(C) are sectional drawings which show still another Example. It is sectional drawing which shows one Example of the pneumatic tire of 2nd Embodiment of this invention. It is sectional drawing which shows an example of the conventional tire.

Explanation of symbols

2 Tread portion 3 Side wall portion 4 Bead portion 5 Bead core 6 Carcass 6A, 6B Carcass ply 7 Belt layers 7A, 7B Belt ply 10P Split ply piece C Tire equator E1 One end E2 Other end

Claims (3)

A pneumatic radial comprising a carcass made of two carcass plies folded around a bead core of the bead part from the tread part to the sidewall part, and a belt layer made of a plurality of belt plies arranged in the tread part. Tire,
Of the two carcass plies, at least the radially outer carcass ply has one end on the outer side in the tire axial direction from the tire equator, and extends from the one end to the inner side in the tire radial direction and is folded around the bead core. While consisting of a pair of left and right split ply pieces where the other end is interrupted,
The pneumatic radial tire is characterized in that the one end of the split ply piece is sandwiched between the belt plies.   One end and the other end of the divided ply piece are sandwiched between the belt plies. A pneumatic radial comprising a carcass made of a single carcass ply folded around a bead core of the bead part from the tread part to the side wall part and a belt layer made of a plurality of belt plies arranged in the tread part. Tire,
The carcass ply is composed of a pair of left and right split ply pieces having one end on the outer side in the tire axial direction from the tire equator and extending from the one end to the inner side in the tire radial direction, being folded around the bead core and interrupted at the other end. ,
A pneumatic radial tire characterized in that the one end and the other end of the split ply piece are sandwiched between the belt plies.

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