JP2007161026A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the weight of a pneumatic tire while excellent high-speed durability and maneuvering stability are secured. <P>SOLUTION: A belt layer 7 consisting of an inner 7A and an outer belt ply 7B is provided outside in radial direction of a carcass 6. The inner belt ply 7A consists in a jointless ply 11 formed by winding round a steel cord 10A spirally at an angle θi of 5° or less relative to the tire circumferential direction, while the outer belt play 7B consists in a cut-end play 12 formed by arranging a steel cord 10B in inclination at an angle θo of 10-70° relative to the tire circumferential direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire that can achieve weight reduction while ensuring excellent high-speed durability by improving a belt layer.

  In the radial tire, as shown in FIG. 5, in order to reinforce the tread portion a and ensure excellent steering stability and durability, a tough belt layer c is formed on the outer side in the radial direction of the carcass b that forms the skeleton of the tire. Forming. The belt layer c is usually composed of two cut-end belt plies c1 and c2 in which steel cords are inclined and arranged at an angle of, for example, 15 to 30 ° with respect to the tire circumferential direction. By placing the steel cords with different inclination directions so that the steel cords cross each other between the plies, the belt rigidity is increased and the reinforcing effect is improved.

  However, in such cut-end belt plies c1 and c2, the steel cords are cut and cut off at the outer end portions ce, so that the restraining force on the tire is weakened. Therefore, when traveling at high speed, so-called lifting occurs in which the tread shoulder portion sh is pushed outward in the radial direction by centrifugal force. As a result, distortion and heat generation increase in the tread shoulder portion sh, and the outer end ce of the belt layer c is increased. Reduces high-speed endurance performance such as inducing cord looseness.

  Therefore, for example, in a tire having a maximum speed notation of the H range or higher, conventionally, a jointless band ply d having a high tagging effect in which a band cord such as nylon is spirally wound in the circumferential direction on the outer side in the radial direction of the belt layer c. And restraining the lifting by increasing the binding force at the outer end ce of the belt layer c. (See, for example, Patent Document 1).

Japanese Utility Model Publication No. 61-15604

  However, the formation of such a band ply has a problem that fuel efficiency is lowered due to an increase in tire weight, and productivity and cost are increased.

  Therefore, in the present invention, two belt layers, a radially inner belt ply composed of a jointless ply in which a steel cord is spirally wound, and a radially outer belt ply composed of a cut end ply in which steel cords are inclined are arranged. For the purpose of providing a pneumatic tire that can suppress lifting without providing a band ply, and can achieve weight reduction while ensuring excellent high-speed durability and steering stability, based on the structure. Yes.

In order to achieve the above object, the invention of claim 1 of the present application is arranged on the carcass extending from the tread portion through the sidewall portion to the bead core of the bead portion, on the inner side of the tread portion and on the radially outer side of the carcass. A pneumatic tire comprising a belt layer,
The belt layer is composed of an inner belt ply arranged on the inner side in the radial direction and an outer belt ply placed on the outer side in the radial direction,
In addition, the inner belt ply is a jointless ply in which a steel cord is spirally wound at an angle θi of 5 ° or less with respect to the tire circumferential direction, and the outer belt ply is connected to the steel cord in the tire circumferential direction. The cut end ply is arranged at an angle θo of 10 to 70 ° with respect to the angle.

In the invention of claim 2, the ply width Wi in the tire axial direction of the inner belt ply is in the range of 80 to 120% of the ground contact width TW of the tread portion, and the ply width in the tire axial direction of the outer belt ply. The width Wo is characterized by being in the range of 50 to 100% of the ply width Wi.
The invention of claim 3 is characterized in that a cord reinforcing layer using a tire cord is not disposed on the outer side in the radial direction of the belt layer.

  The “grounding width TW” is the outer end of the tread grounding region (grounding) that is grounded when a normal load is applied to a tire in a normal internal pressure state that is assembled with a normal rim and filled with a normal internal pressure and is grounded on a flat surface. It means the width in the tire axial direction between the ends. The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based, for example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO means "Measuring Rim". The “regular internal pressure” is the air pressure determined by the standard for each tire. The maximum air pressure for JATMA, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” for TRA, In the case of ETRTO, it means “INFLATION PRESSURE”, but in the case of passenger tires, it is 180 kPa. The “regular load” is the load specified by the standard for each tire. The maximum load capacity shown in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” is the maximum load capacity for JATMA and TRA for TRA. In the case of ETRTO, it means a load obtained by multiplying "LOAD CAPACITY" by 0.88.

  In the present specification, unless otherwise specified, the dimensions and the like of each part of the tire are values specified in the normal internal pressure state.

  Since the present invention is configured as described above, it is possible to suppress lifting associated with high-speed running without providing a cord reinforcement layer such as a band ply, and while maintaining excellent high-speed durability and steering stability, the weight is reduced. Can be achieved. In addition, it can greatly contribute to productivity improvement and cost reduction.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view in a normal internal pressure state illustrating a case where the pneumatic tire of the present invention is a tire for a passenger car having a maximum speed notation of the H range or higher.

  In FIG. 1, a pneumatic tire 1 is disposed on a carcass 6 extending from a tread portion 2 through a sidewall portion 3 to a bead core 5 of a bead portion 4, inside the tread portion 2, and radially outside the carcass 6. The belt layer 7 is provided. Note that a cord reinforcing layer (for example, a conventional band ply) using a tire cord is not formed on the outer side in the radial direction of the belt layer 7.

  The carcass 6 is formed of one or more, in this example, one carcass ply 6A in which carcass cords are arranged at an angle of, for example, 65 to 90 ° with respect to the tire circumferential direction. As the carcass cord, an organic fiber cord such as nylon, polyester, or rayon is suitably employed from the viewpoint of weight reduction. The carcass ply 6A includes a series of ply turn-up portions 6b that are turned back from the inner side in the tire axial direction around the bead core 5 to both ends of the ply main body portion 6a straddling the bead cores 5 and 5. A bead apex rubber 8 for bead reinforcement extending in a radially outward direction from the bead core 5 is disposed between the ply main body 6a and the ply turn-up portion 6b.

  In this example, the carcass 6 has no so-called high turn-up structure in which the radial height h0 of the ply turn-up portion 6b from the bead base line BL is larger than the radial height h1 of the bead apex rubber 8. The tire has increased lateral rigidity. Although the height h1 of the bead apex rubber 8 is not particularly restricted, it is preferably in the range of 25% to 40% of the tire cross-section height H as in the case of a conventional tire, and the ply turn-up portion 6b has a height thereof. If h0 is larger than the apex height h1, it can be terminated radially inward or outward from the maximum tire width position Pm or near the maximum tire width position Pm as in this example. The “bead base line BL” means a tire axial line passing through a rim diameter position defined by a standard based on the tire.

  Next, the belt layer 7 has a two-piece structure of an inner belt ply 7A arranged on the inner side in the radial direction and an outer belt ply 7B placed on the outer side of the belt ply 7A. The tire is arranged around the equator C.

  As shown in FIG. 3, the inner belt ply 7A is formed of a jointless ply 11 in which a steel cord 10A (belt cord) is spirally wound at an angle θi of 5 ° or less with respect to the tire circumferential direction. ing. Specifically, the jointless ply 11 uses a small strip 13 (shown in FIG. 4) in which one or a plurality (in this example, a plurality) of steel cords 10A are covered with a topping rubber. Are sequentially wound in a spiral. As a mode of winding the strip 13 in a spiral shape, for example, either a mode in which the side edges of the strip 13 are in contact with each other, a mode in which they are overlapped, or a mode in which they are separated may be used. .

  On the other hand, the outer belt ply 7B is formed by a cut end ply 12 in which steel cords 10B (belt cords) are inclinedly arranged at an angle θo of 10 to 60 ° with respect to the tire circumferential direction. The ply width Wi of the inner belt ply 7A in the tire axial direction is equal to or larger than the ply width Wo of the outer belt ply 7B in the tire axial direction. Therefore, the ply width Wi forms the maximum belt width Wmax.

  Such a belt layer 7 can form a strong truss structure in cooperation with the carcass cord because each steel cord 10A, 10B intersects with each other at an angle α of (θo−θi) or (θo + θi). The tread portion 2 is reinforced with a hoop effect. As a result, a sufficient cornering force can be generated and excellent steering stability can be exhibited. In addition, since the inner belt ply 7A forming the maximum belt width Wmax is formed of the jointless ply 11, the outer layer 7e of the belt layer 7 can exert a high restraining force on the tire. Therefore, lifting can be effectively suppressed, and high-speed durability can be improved to the same level as or higher than that of a conventional tire having a cord reinforcement layer such as a band ply.

  The ply width Wi of the inner belt ply 7A is in the range of 80 to 120% of the ground contact width TW of the tread portion 2, and the ply width Wo of the outer belt ply is 50 to 100% of the ply width Wi. A range is preferred. If the ply width Wi is less than 80% of the ground contact width TW, lifting at the tread shoulder portion cannot be sufficiently suppressed. Conversely, if it exceeds 120%, the ply end of the inner belt ply 7A is too close to the tire outer surface. This increases the strain at the ply end and causes damage. On the other hand, if the ply width Wo is less than 50% of the ply width Wi, the truss structure forming region becomes too narrow, and a sufficient cornering force cannot be generated and the steering stability tends to be reduced. The binding force at 7e is reduced, which is disadvantageous for high-speed durability. On the other hand, if it exceeds 100%, stress concentrates on the cut ends of the steel cords 10B that are interrupted at the ply ends of the outer belt ply 7A, and damage is likely to occur. From such a viewpoint, the lower limit value of the ply width Wo is desirably 60% or more of the ply width Wi, and the upper limit value is desirably 90% or less.

  If the cord angle θo of the outer belt ply 7B is smaller than 10 °, the belt rigidity becomes excessive and the ride comfort is lowered. Conversely, if the cord angle θo exceeds 70 °, the belt rigidity becomes excessively low and the cornering force is reduced. Decrease in driving stability such as reduction. From this point of view, the lower limit value of the cord angle θo is desirably 20 ° or more, and the upper limit value is desirably 60 ° or less.

  In the conventional belt layer formed with two cut end plies, the ply width of each cut end ply is different in order to avoid stress concentration at the belt end. A ply material is required for each tire size. However, in the belt layer 7 of the present embodiment, since the inner belt ply 7A is formed by the jointless ply 11, the ply width can be freely adjusted by the number of windings of the strip 13. Therefore, the type of ply material that is an intermediate stock at the time of tire production can be halved, and improvement in productivity and cost reduction can be achieved even when compared with a tire having a low maximum speed notation range that does not include a band ply.

  In the belt layer 7, depending on the type, size, and required characteristics of the tire, the cord configurations (including material, twisted structure, thickness, etc.) of the steel cords 10A, 10B, the cord driving density, and the like are belt plies 7A, 7B. Can be set for each.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

  A tire having a tire size of 195 / 65R15 91H was prototyped based on the specifications in Table 1, and the weight, cornering force, riding comfort, and high-speed durability of each sample tire were evaluated. The specifications other than the belt layer and the band layer are substantially the same.

When the belt ply is a cut end ply (indicated as CEP in the table), the cord configuration is steel (2 + 2 / 0.23), the cord driving density is 38 pieces / 5 cm, and the jointless ply (indicated as JLP in the table) In this case, the cord configuration is steel (3 × 3 / 0.20), and the cord driving density is 30 pieces / 5 cm.
The band layer consists of a jointless ply in which a band cord (nylon 1400 dtex / 2) is spirally wound. The band layer that covers the entire width of the belt layer is a full band ply (indicated as FB in the table), and only the outer end of the belt layer. What covered the cover was described as an edge band ply (denoted as EB in the table).

(1) Tire mass;
The mass per tire was measured and displayed as an index with Comparative Example 1 taken as 100. The smaller the index, the lighter.
(2) Cornering force (CF);
Measured under the conditions of rim (15 × 6JJ), internal pressure (200 kPa), slip angle (4 °), longitudinal load (4.35 kPa) using an indoor tester. ing. The larger the index, the greater the cornering force and the better the steering stability.
(3) Ride comfort;
A sample tire is mounted on all wheels of a domestic FF passenger car (displacement 2000 cc) with a rim (15 × 6JJ) and internal pressure (200 kPa), and runs on an asphalt tire test course. Comparison was made with an index of 6.0. The higher the number, the better.
(4) High speed durability;
Using the drum running test machine, the running time until damage was caused by running under the conditions of rim (15 × 6JJ), internal pressure (190 kPa), load (6.96 kN), speed (160 km / H). Comparison was made with an index of 100. The higher the number, the better.

  As shown in the table, it can be confirmed that the tires of the examples can improve the high-speed durability to the same level as or higher than the tire having the band ply even when the band ply is eliminated and the weight is reduced. . Further, it can be confirmed that the steering stability and the ride comfort can be adjusted by the ply widths Wo and Wi and the cord angle θo.

It is sectional drawing which shows one Example of the pneumatic tire of this invention. It is sectional drawing which expands and shows the tread part. It is an expanded view which expand | deploys and shows the code | cord | chord arrangement | sequence of a belt layer on a plane. It is a perspective view which shows a strip. It is sectional drawing which abbreviate | omits the structure of the conventional tire.

Explanation of symbols

2 Tread portion 3 Side wall portion 4 Bead portion 5 Bead core 6 Carcass 7 Belt ply 7B in belt layer 7A Belt plies 10A and 10B outside Steel cord 11 Jointless ply 12 Cut end ply

Claims (3)

A pneumatic tire comprising a carcass extending from a tread portion through a sidewall portion to a bead core of a bead portion, and a belt layer disposed inward of the tread portion and radially outward of the carcass,
The belt layer is composed of an inner belt ply arranged on the inner side in the radial direction and an outer belt ply placed on the outer side in the radial direction,
In addition, the inner belt ply is a jointless ply in which a steel cord is spirally wound at an angle θi of 5 ° or less with respect to the tire circumferential direction, and the outer belt ply is connected to the steel cord in the tire circumferential direction. A pneumatic tire characterized in that it is a cut end ply that is inclined and arranged at an angle θo of 10 to 70 °.   The ply width Wi in the tire axial direction of the inner belt ply is in the range of 80 to 120% of the contact width TW of the tread portion, and the ply width Wo in the tire axial direction of the outer belt ply is the ply width Wi. The pneumatic tire according to claim 1, characterized by being in the range of 50 to 100%.   3. The pneumatic tire according to claim 1, wherein a cord reinforcing layer using a tire cord is not disposed on an outer side in the radial direction of the belt layer.

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