JP2011025823A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving driving stability when accelerating from low speed to high speed during quick cornering travelling on a dry road. <P>SOLUTION: A carcass 24 is formed by a first carcass ply 20 and a second carcass ply 22 each having an end portion in the width direction that folds a bead core 18 from the tire width direction inner side toward the tire width direction outer side, and the end portions in the width direction are placed between an carcass body portion and a crossed belt layer 26 so that a so-called envelope structure is provided. By setting an inclination angle of a carcass code relative to the tire radial direction in a range of 4-10 degrees, the pneumatic tire 10 can have flexibility in the front-back direction and high rigidity in the lateral direction. Thus, the driving stability during accelerating from low speed to high speed and quick cornering travelling on a dry road can be improved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of improving steering stability when accelerating from a low speed to a high speed while rapidly cornering on a dry road surface.

When cornering on a dry road quickly and accelerating from low speed to high speed, tires need high lateral rigidity and supple rigidity in the front-rear direction, but the conventional technology increases the rigidity of the entire carcass layer. By doing so, the rigidity of the tire has been increased, and the cornering stability has been enhanced.
For example, Patent Documents 1 and 2 disclose structures that increase the rigidity of the carcass layer by extending the folded portion of the carcass that folds the bead core from the inside to the outside of the tire toward the belt end side.

JP 2004-42755 A JP 2007-168601 A

However, when the rigidity of the entire tire is increased, there is a problem in that quick acceleration cannot be obtained because flexibility is lost when accelerating from a low speed.
Conventionally, in a radial tire, the extending direction of the carcass cord is brought closer to the tire equator direction, that is, the tire is formed by inclining the carcass cord extending in the radial direction (tire radial direction) with respect to the tire radial direction at the tire side portion. Although the overall rigidity is increased, this method has the effect of mainly increasing the rigidity in the lateral direction, but at the same time it leads to an increase in the rigidity in the front-rear direction, and is negative in terms of obtaining quick acceleration. .

  The present invention has been made to solve the above-mentioned problems and enhances the insufficient lateral rigidity while leaving the flexibility in the front-rear direction, and in particular, accelerates from low speed to high speed while fast cornering on a dry road surface. An object of the present invention is to provide a pneumatic tire capable of improving the steering stability.

  The pneumatic tire according to claim 1 has a pair of bead cores and a toroidal shape extending from one bead core to the other bead core, and a width direction end portion folds the bead core from the inner side in the tire width direction to the outer side in the tire width direction. A carcass consisting of two carcass plies, a main body portion of the carcass ply extending from one bead core to the other bead core, and a folded-back portion of the carcass ply. A bead filler extending while gradually decreasing the thickness toward the outer side of the carcass, and a belt disposed on the outer side in the tire radial direction of the carcass, wherein the end portions in the width direction of the two carcass plies are the main body and the belt. The carcass cord included in the carcass ply is inclined with respect to the tire radial direction. Degrees is set in the range of 4 to 10 °, said carcass cord of one of said carcass ply, said carcass cord of the other of the carcass plies cross each other.

Next, the operation of the pneumatic tire according to claim 1 will be described.
The carcass of a pneumatic tire according to claim 1 is composed of two carcass plies whose end portions in the width direction are folded back from the inner side in the tire width direction to the outer side in the tire width direction, and the width direction of the two carcass plies. The end portion has a so-called envelope structure arranged between the main body portion and the belt, and the inclination angle of the carcass cord included in the carcass ply with respect to the tire radial direction is set within a range of 4 to 10 °. Therefore, it is possible to increase the lateral rigidity while leaving the flexibility in the front-rear direction. As a result, it is possible to improve steering stability when accelerating from a low speed to a high speed while rapidly cornering on a dry road surface.
If the angle of inclination of the carcass cord with respect to the tire radial direction is less than 4 °, the lateral rigidity cannot be increased.
On the other hand, when the inclination angle of the carcass cord with respect to the tire radial direction exceeds 10 °, the flexibility in the front-rear direction cannot be obtained.

  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the side rubber layer disposed at an outer side in the tire width direction of the carcass and forming at least a bead portion and a sidewall portion, and the side rubber layer And a side portion reinforcing layer made of rubber which is disposed along the carcass inside and is harder than the side rubber layer and has a JIS Shore A hardness of 85 to 97 degrees.

Next, the operation of the pneumatic tire according to claim 2 will be described.
In the pneumatic tire according to claim 2, a side portion reinforcing layer made of rubber that is harder than the side rubber layer and has a JIS Shore A hardness of 85 to 97 degrees is provided on the outer side in the tire width direction of the carcass. Because it is arranged, it suppresses the cord breakability due to the concentration of carcass strain often seen when the reinforcing layer made of steel cord is arranged on the outer side in the carcass tire width direction, and at the same time increases without damaging the flexibility in the front-rear direction At the same time, it is possible to increase the lateral rigidity without impairing the flexibility in the front-rear direction.

As described above, since the pneumatic tire according to claim 1 has the above-described configuration, particularly high steering stability required when accelerating from low speed to high speed while quickly cornering on a dry road surface can be obtained. It has an excellent effect.
Since the pneumatic tire according to claim 2 has the above-described configuration, acceleration can be increased.

It is sectional drawing of the pneumatic tire which concerns on one Embodiment of this invention. It is sectional drawing of a belt cord. It is sectional drawing of the pneumatic tire which concerns on a prior art example.

A pneumatic tire 10 according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the pneumatic tire 10 of the present embodiment includes a pair of bead portions 12, a pair of tire sidewall portions 14, and a tread portion 16 that is continuous with both tire sidewall portions 14. FIG. 1 illustrates the left half of the pneumatic tire 10, which is symmetrical with respect to the tire equatorial plane CL.

  A bead core 18 is embedded in the bead portion 12, and the pneumatic tire 10 according to the present embodiment has a first carcass ply 20 and a second carcass ply 22 straddling from one bead core 18 to the other bead core 18 in a toroidal shape. A carcass 24 is provided.

(Carcass)
Each of the first carcass ply 20 and the second carcass ply 22 is configured by rubber coating a plurality of carcass cords (not shown) made of organic fibers such as nylon and polyester arranged in parallel with each other. In the tire side portion, the carcass cord of the first carcass ply 20 and the carcass cord of the second carcass ply 22 are inclined at a small angle in directions opposite to each other with respect to the tire radial direction (radial direction). Therefore, the carcass cord of the first carcass ply 20 and the carcass cord of the second carcass ply 22 intersect each other.

  The inclination angle of the carcass cord of the first carcass ply 20 and the carcass cord of the second carcass ply 22 with respect to the tire radial direction is set to be larger than that of the conventional general radial tire, and is 4 to 10 °. Is set within the range of preferably 6 to 10 °.

  Each of the first carcass ply 20 and the second carcass ply 22 has its end portion in the width direction folded back from the inner side in the tire width direction toward the outside, and the folded portion 20B of the first carcass ply 20 and The folded portions 22B of the two carcass plies 22 each extend to the inner side of the belt end via the tire sidewall portion 14.

That is, the end portion 20E of the first carcass ply 20 and the end portion 22E of the second carcass ply 22 are sandwiched between the cross belt layer 26 disposed on the outer side in the tire radial direction of the carcass 24 and the carcass ply main body portion 22A. In addition, the vicinity of the end portion of the folded portion 20B and the vicinity of the end portion of the folded portion 22B overlap each other with the cross belt layer 26 (so-called envelope structure).
In the present embodiment, the end 20E of the first carcass ply 20 is disposed closer to the tire equatorial plane CL than the end 22E of the second carcass ply 22.

(Cross belt layer)
The cross belt layer 26 of the present embodiment is composed of two belt plies, a first belt ply 28 and a second belt ply 30.
Each of the first belt ply 28 and the second belt ply 30 is a rubber coating in which a plurality of steel cords are arranged in parallel to each other.

  For the first belt ply 28 and the second belt ply 30, a steel cord 32 shown in a sectional view in FIG. The steel cord 32 includes a core 36 composed of one steel filament 34 and a sheath 38 composed of a plurality of steel filaments 34 arranged around the core 36, and a plurality of steels constituting the sheath 38. One in which the filament 34 is twisted and the cross section is formed in an approximately oval shape can be used.

  The structure of the steel cord 32 of this embodiment is 1 + 6 × 0.280. The cord diameter of the steel cord 32 is 0.89 mm in the minor axis and 0.99 mm in the major axis. The structure of the steel cord 32, the cord diameter, the diameter of the steel filament 34, and the like shown here are examples, and may be changed as appropriate.

  The number of steel cords 32 driven in the first belt ply 28 and the second belt ply 30 is set to 24/50 mm in the present embodiment, but the present invention is not limited to this and is appropriately changed. .

  The steel cord 32 of the first belt ply 28 and the steel cord 32 of the second belt ply 30 are inclined in directions opposite to each other with respect to the tire equatorial plane CL. Note that the gauges of the first belt ply 28 and the second belt ply 30 of the present embodiment are 1.43 mm, respectively, but the present invention is not limited to this and may be changed as appropriate.

(Belt reinforcement layer)
A first belt reinforcing layer 40 that covers the entire cross belt layer 26 is disposed outside the cross belt layer 26 in the tire radial direction, and the first belt reinforcing layer is disposed near the end of the first belt reinforcing layer 40. A narrow second belt reinforcing layer 42 corresponding to only the vicinity of the end of 40 is disposed.

  The first belt reinforcing layer 40 and the second belt reinforcing layer 42 of the present embodiment are configured to include a polyethylene tphthalate cord (hereinafter referred to as a PEN cord) that extends substantially in the tire circumferential direction. A ribbon-like strip formed by rubber coating a plurality of PEN cords arranged in parallel with each other can be formed by spirally winding the belt on the outer peripheral surface of the belt.

  The configuration of the PEN cord of this embodiment is 1100 dtex / 2, the number of driving is 50/50 mm, and the number of twists (times / 10 cm) is 39 × 39. Moreover, the gauge of the belt reinforcement layer 40 of this embodiment is 0.90 mm. The configuration of the PEN cord, the number of driving, the number of twists, and the gauge of the belt reinforcing layer 40 are merely examples, and the present invention is not limited to this and can be changed as appropriate.

(Tread part, diamond side wall part)
A tread rubber layer 44 forming the tread portion 16 is disposed on the outer side in the tire radial direction of the first belt reinforcing layer 40 and the second belt reinforcing layer 42, and a bead portion is disposed on the outer side in the tire axial direction of the carcass 24. 12 and a side rubber layer 46 that forms the outer surface of the diamond sidewall 14 is disposed.

(Bead filler)
A bead filler 48 extending from the bead core 18 to the outer side in the tire radial direction while gradually decreasing the thickness between the main body portion 22A and the turn-up portion 22B of the second carcass ply 22 extending from one bead core 18 to the other bead core 18. Is arranged.
The bead filler 48 is made of rubber harder than the rubber forming the side rubber layer 46.

(Flipper)
Between the bead filler 48 and the second carcass ply 22, a single layer of a flipper 50 having a plurality of highly elastic organic fiber cords that fold the bead core 18 from the inner side in the tire width direction to the outer side in the tire width direction is disposed. Yes.
The flipper 50 is a rubber coating in which a plurality of highly elastic organic fiber cords are arranged. The organic fiber cord used in the flipper 50 of the present embodiment is an aromatic polyamide cord, and the angle with respect to the tire radial direction is set within a range of 40 ° to 55 °.

  The end 50Eo on the outer side in the tire width direction of the flipper 50 is disposed on the outer side in the tire radial direction of the bead filler 48 in the tire radial direction, and the end 50Ei on the inner side in the tire width direction of the flipper 50 is on the bead filler 48. It is arranged on the inner side in the tire radial direction than the tire radial direction outer end 48E.

(Side reinforcement layer)
A side portion reinforcing layer 52 is disposed along the carcass 24 inside the bead portion 12 and the sidewall portion 14 on the outer side in the tire width direction of the carcass 24.
The side portion reinforcing layer 52 is made of a rubber having higher elasticity than the rubber forming the side rubber layer 46, and the JIS Shore A hardness is set within a range of 85 to 97 degrees.

(Function)
The carcass 24 of the pneumatic tire 10 of the present embodiment includes a first carcass ply 20 and a second carcass ply 22 whose end portions in the width direction are folded back from the inner side in the tire width direction to the outer side in the tire width direction. The end portion in the width direction has a so-called envelope structure arranged between the carcass ply main body and the cross belt layer 26, and the inclination angle of the carcass cord with respect to the tire radial direction is set within a range of 4 to 10 °. Therefore, the pneumatic tire 10 has high lateral rigidity while maintaining the flexibility in the front-rear direction, and improves steering stability when accelerating from low speed to high speed while rapidly cornering on a dry road surface. be able to.
Further, the pneumatic tire 10 according to the present embodiment has the side portion reinforcing layer 52 made of hard rubber disposed on the outer side in the tire width direction of the carcass 24, so that the lateral rigidity is maintained without losing the flexibility in the front-rear direction. Can be improved.

  In addition, the pneumatic tire 10 of the present embodiment includes a cross belt layer 26 including a first belt ply 28 and a second belt ply 30 each including a plurality of steel cords 32 having a two-layer twist structure. The tire crown portion is reinforced by the first belt reinforcing layer 40 and the second belt reinforcing layer 42 including a plurality of polyethylene naphthalate cords, and the folded portion 20B and the second carcass ply of the first carcass ply 20 are further reinforced. Since the folded portion 22B of 22 extends to the inside of the belt end and is disposed in the tire crown portion, the rigidity of the tire crown portion is higher than that of the conventional tire. As a result, it is possible to improve the ground contact property at the time of sudden acceleration, sudden deceleration, and sudden turning compared to the conventional tire, and higher motion performance than the conventional tire can be obtained.

In the pneumatic tire 10 of the present embodiment, the inclination angle of each carcass cord of the first carcass ply 20 and the second carcass ply 22 is set to be larger than that of a conventional general radial tire (tire diameter). In the range of 4 to 10 ° with respect to the direction, preferably in the range of 6 to 10 °), and each ply end portion is disposed on the tire equatorial plane CL side with respect to the belt end. Since the flipper 50 including the highly elastic aromatic polyamide cord is disposed between the filler 48 and the second carcass ply 22, the rigidity of the bead portion 12 and the tire sidewall portion 14 becomes higher than that of the conventional tire, so that the tire side The rigidity balance between the portion and the tread portion is improved, and the effect of making the tire crown portion highly rigid is sufficiently exhibited.
Therefore, the pneumatic tire 10 of the present embodiment is suitable for mounting on a racing vehicle that frequently uses rapid acceleration, rapid deceleration, and sudden turning.
In the pneumatic tire 10 of the present embodiment, polyethylene naphthalate cords are used for the first belt reinforcing layer 40 and the second belt reinforcing layer 42, but other organic materials having an elastic modulus equivalent to that of the polyethylene naphthalate cord. A fiber cord may be used.

(Test example)
In order to confirm the effect of the present invention, a pneumatic tire of a conventional example, a pneumatic tire of a comparative example, and a pneumatic tire of an example to which the present invention is applied are prepared, and a response index, a traction index, and a circuit course are prepared. Comparison of lap time (best time) on (dry road surface) was performed.

Example: The tire of the present embodiment having the structure shown in FIG.
Conventional example: a tire having the structure shown in FIG. One of the two carcass plies has an envelope structure. Nylon cords (structure: the same as in the embodiment) are used for the first belt reinforcing layer 40 and the second belt reinforcing layer 42. In place of the flipper, an insert 54 made of a steel cord is arranged along the outer side surface of the bead filler 48 in the tire width direction. The other structure is the same as the embodiment.
Comparative Example 1: Structure similar to the example except that the angle of the carcass cord was set to 3 ° (outside the scope of the present invention).
Comparative example 2: Structure similar to the example except that the angle of the carcass cord was set to 11 ° (outside the scope of the present invention).
The tire size is 245 / 45ZR18.
Responsiveness index: lateral stiffness ratio (conventional example is 100). The larger the index value, the better the response. The lateral stiffness of the tire (normal static spring test; average value measured with two types of load) is 8.5 JJ-18, internal pressure is 210 kPa, and the measurement load (vertical load: 3.19 kN for the first time, 4 for the second time). .66 kN).
Traction index: Ratio of inverse reciprocal rigidity (conventional example is 100) The larger the index value, the better the traction. The front and rear rigidity of the tire (normal static spring test; average value measured with two types of loads) is: measurement rim 8.5JJ-18, internal pressure 210 kPa, measurement load (vertical load: first 3.19kN, second 4 .66 kN).

本発明の適用された実施例のタイヤは、応答性及びトラクション性能がバランス良く向上したことで、素早いコーナリング走行と低速から高速にかけて素早い加速が可能となり、タップタイムの短縮が実現した。

The tires of the examples to which the present invention is applied have improved responsiveness and traction performance in a well-balanced manner, enabling quick cornering running and quick acceleration from low speed to high speed, and shortening the tap time.

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Bead part 14 Tire side wall part 16 Tread part 18 Bead core 20 1st carcass ply 20A main body part 20B Folding part 22 2nd carcass ply 22A Main body part 22B Folding part 24 Carcass 26 Crossing belt layer 32 Steel cord 34 Steel Filament 36 Core 38 Sheath 40 First belt reinforcing layer 42 Second belt reinforcing layer 50 Flipper 52 Side portion reinforcing layer

Claims (2)

A pair of bead cores;
A carcass composed of two carcass plies straddling from one of the bead cores to the other of the bead cores in a toroidal manner, with the end portions in the width direction folded back from the inside in the tire width direction to the outside in the tire width direction of the bead core;
A bead that is disposed between a body portion of the carcass ply extending from one bead core to the other bead core and a folded portion of the carcass ply and extends gradually from the bead core toward the outer side in the tire radial direction. A filler,
A belt disposed on the outer side in the tire radial direction of the carcass;
With
The width direction end portions of the two carcass plies are disposed between the main body portion and the belt,
The inclination angle of the carcass cord included in the carcass ply with respect to the tire radial direction is set within a range of 4 to 10 °,
A pneumatic tire in which the carcass cord of one carcass ply and the carcass cord of the other carcass ply intersect each other. A side rubber layer disposed outside the carcass in the tire width direction and forming at least a bead portion and a sidewall portion;
A side portion reinforcing layer made of rubber disposed along the carcass inside the side rubber layer, harder than the side rubber layer, and having a JIS Shore A hardness of 85 to 97 degrees;
The pneumatic tire according to claim 1, comprising:

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