JP2733428B2 - Pneumatic tire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a tire for high-speed running, particularly by improving uniformity.
The present invention relates to a pneumatic tire capable of improving steering stability and improving tire durability.

[0002]

2. Description of the Related Art In recent years, with the development of a highway network, the speed of passenger cars has been increased, and the speed and load of light vans and light trucks have also been increased. In particular, flat tires having a flat rate of 60% or less have been widely used as tires used for tires, particularly tires for sports cars. In such a flat tire, it is necessary to increase the rigidity of the sidewall portion and the bead portion in order to ensure the vehicle's kinetic performance.

Conventionally, in a tire aiming at high performance, a carcass a is formed by using two carcass plies b and b as shown in FIG. A so-called 2-0 configuration in which the bead core c of the bead portion c is wound up in the same direction is common.

[0004]

However, when the carcass has the above-mentioned 2-0 construction, it is difficult to secure sufficient lateral, longitudinal and torsional stiffness and to improve the steering stability. In addition, there is a problem that the weight of the tire increases due to the carcass configuration of the 2-0 configuration.

The inventor of the present invention has conducted various trials and experiments to solve the above-mentioned problems. As a result, a) a carcass is composed of two carcass plies, one of which is a bead core that is turned inward and outward from a high position. While winding up, the other one has a 1-1 configuration in which it is lowered between the bead apex and the folded portion, and the other one is not bent at its lower end along the lower surface of the bead core, Break at the bottom of the outward facing surface of the bead core.

(B) Further, the side wall and the bead are reinforced with a reinforcing layer, and the positions of the inner end and the outer end of the reinforcing layer are regulated, so that the above problem can be solved and the durability is improved. Have been found, and the present invention has been completed.

[0007] An object of the present invention is to provide a pneumatic tire that can improve the steering stability and enhance the durability even with a flat tire.

[0008]

According to the present invention, a bead portion is folded back from the inside to the outside around the bead core of the bead portion and extends upward from the bead core to a main body portion extending from the tread portion to the bead portion through the sidewall portion. The first carcass ply having a folded portion of a high turn-up structure that folds the outward surface side of the bead apex and the tread portion from the tread portion to the sidewall portion, passing between the folded portion and the outward surface of the bead apex. A carcass including a second carcass ply having a lower end interrupted near a lower end of an outward surface of the bead core, a belt layer disposed inside the tread portion and outside the second carcass ply, and the second carcass ply And a folded portion of the first carcass ply. A reinforcing layer consisting of a ply using a steel cord which is inclined in the direction of rotation of the tire at an angle of 60 to 80 ° with respect to the line, and in a no-load state where the rim is assembled and filled with a normal internal pressure, Apex, the height of the tip J from the bead baseline is 0.3 times or more of the tire section height H and 0.5 or more.
And a radial inner end D of the reinforcing layer.
An outer line Y parallel to the tire axis passing through an outer point P that radially outwardly separates a distance of 0.067 times the cross-sectional height H from a radially outer end of the bead core; A radially outer end K of the reinforcing layer located in a lower region X sandwiched by an inner line Z parallel to the tire axis passing through the end Q;
Is located at a position radially outwardly at least 0.045 times the tire cross-sectional height H from the tip J of the bead apex, while the tip of the folded portion of the first carcass ply is A pneumatic tire, characterized in that a reinforcing layer is located at a distance of at least 0.045 times the tire cross-sectional height H from the outer end K of the reinforcing layer radially outward.

In the carcass, a reinforcing rubber layer made of a reinforcing rubber ply is interposed between the main body of the first carcass ply and the second carcass ply, and the reinforcing rubber layer has a radially inner end. A first carcass ply having an inner overlapping portion overlapping the folded portion of the first carcass ply by 5 mm or more, and an outer overlapping portion overlapping the belt layer by 5 to 25 mm at a radially outer end portion. The rubber thickness T between the carcass cord of the main body portion and the carcass cord of the second carcass ply is preferably not less than 0.25 times and not more than 4.0 times the diameter of the carcass cord of the first carcass ply. preferable.

[0010]

The first carcass has a turn-up structure with a turn-up structure that turns along the outward surface of the bead apex, and the second carcass ply has the turn-up portion and the outward surface of the bead apex. , The lower end is interrupted near the lower end of the outward surface of the bead core. Thereby, the first and second carcass plies 1-1.
By forming the carcass having the above configuration and forming the side wall portion and the bead portion in a shell configuration, the tension distribution of the first and second carcass plies can be optimized, and the side wall portion has a sufficient lateral direction, front and rear. The steering stability can be improved by increasing the rigidity against the direction and further the twist.

Further, the total length of the ply can be shorter than that of the conventional 2-0 structure in which two carcass plies are folded in the same direction as shown in FIG. 5, and the carcass can be lightened accordingly. .

Further, by passing the second carcass ply between the first carcass ply and the bead apex, the second carcass ply can prevent the end of the ply from being peeled off and can increase the durability of the bead portion. Further, since the lower end is interrupted near the lower end of the outward surface of the bead core, the molding process can be simplified, the cost can be reduced, the uniformity is increased, and the force variation is not reduced.

Further, a reinforcing layer is provided between the second carcass ply and the folded portion of the first carcass ply. As shown in FIG. 3, the reinforcing layer extends up and down in the radial direction and extends outside the radial direction. It is formed by a ply using a steel cord whose end is inclined in a direction of falling in the tire rotation direction at an angle α of 60 to 80 ° with respect to the radius line. The reason why the inclination of the steel cord is restricted in the fixed direction and to the inclination angle α is that a range in which the steering stability is highest is found based on the experimental results as described in the specific example section described later. It is more preferable that the inclination angle α is in the range of 65 to 75 °. If the falling angle α exceeds 80 °, the cord becomes too long at the time of tire molding, and molding becomes difficult.

The reinforcing layer has its radially inner end D positioned in the lower region X according to the above configuration. This inner edge D
If the position is to be located radially inward of the inward line Z that forms the lower limit of the lower region X, tire moldability is inferior, and the rubber thickness I of the bead portion on the radially inner side of the bead core is increased. It will not be stable and the uniformity of the tire will be worse.

On the other hand, when the position of the inner end D is located radially outward of the outer line Y which is the upper limit in the lower region X, the inner end D comes into contact with the rim flange during rolling and receives a large contact pressure. The inner end D will be located in the area where
Edge loosening is likely to occur.

Further, the reinforcing layer has its radially outer end K located radially outward from the tip J of the bead apex at least 0.045 times the tire sectional height H, and the reinforcing layer has the tip J of the bead apex. The stress concentration at the tip portion of the bead apex can be reduced by wrapping. If the outer end K of the reinforcing layer is positioned radially inward of the tip J of the bead apex, a sufficient reinforcing effect cannot be obtained.

The position of the leading end L of the folded portion of the first carcass ply is located radially outward at least 0.045 times the tire sectional height from the position of the outer end K of the reinforcing layer. As described above, the outer end K of the reinforcing layer is separated from the front end L of the folded portion by 5 mm or more in a normal tire for a passenger car. Therefore, the outer end K is wrapped by the folded portion of the first carcass ply. As a result, the concentration of the stress acting on the outer end K of the reinforcing layer can be reduced.

As described above, according to the present invention, the above-mentioned components are organically combined and integrated, so that the steering stability is improved even if the structure is flat, and the carcass, bead apex and the reinforcing layer are prevented from peeling off. It is possible to improve the durability of the resulting tire and economically produce a tire having good force variation.

[0019]

An embodiment of the present invention will be described below with reference to the drawings. 1 to 4, a pneumatic tire 1 is a flat tire 1 having a flatness of 60% or less in this example. The tire 1 has a tread portion 2 forming a tread surface 2A, and a tire radial direction from both sides thereof. It has a pair of sidewall portions 3 extending inward and a bead portion 4 extending inward of the sidewall portions 3.

The pneumatic tire 1 has a main body 9 extending from the tread portion 2 to the bead portion 4 through the sidewall portion 3.
a, a bend core 5 of the bead portion 4 has a turn-up portion 9b that turns back the outward surface 6a side of the bead apex 6 extending from the inside to the outside and upward from the bead core 5;
And a second carcass ply 10 extending downward from the tread portion 2 to the side wall portion 3 through the folded portion 7 and the outward surface 6a of the bead apex 6. And

Further, the side wall portion 3 and the bead portion 4
In the above, the reinforcing layer 11 is disposed between the second carcass ply 10 and the folded portion 9b of the first carcass ply 9. Further, in this embodiment, the first wall portion 3B extending from the buttress portion 3B to the tire maximum width point B has the first width.
The reinforcing rubber layer 12 is interposed between the main body portion 9a of the carcass ply 9 and the second carcass ply 10.

A belt layer 8 is provided inside the tread portion 2 and outside the carcass 7, and in this embodiment, a band layer 16 for preventing the lifting of the belt layer 8 is provided outside the belt layer 8. Is established. The bead apex 6 is harder than the side wall rubber 17 forming the outer wall of the side wall 3 and has a JISA hardness of 80-9.
It forms an elongated triangle formed by 0 degree rubber. Further, the bead apex 6 has a height HC from the bead base line BL at the tip end J of 0.3 to 0.5 times the tire section height H. In this embodiment, the hardness of the sidewall rubber 17 is set to 50 to 60 degrees in JISA hardness.

The first and second carcass plies 9, 10
Uses an organic fiber, such as nylon, polyester, rayon, or aromatic polyamide, of 80 to 90 with respect to the tire equator C.
The first carcass ply 9 has a radially arranged carcass cord inclined at an angle of ° and arranged in parallel with each other, and the first carcass ply 9 has the upper end of the folded portion 9b positioned above the tire maximum width point B. It has a so-called high turn-up structure. The lower end of the second carcass ply 10 is located near the lower end of the outward facing surface 5a of the bead core 5, and the first and second carcass 9, 10 form a carcass 7 having a 1-1 HTU configuration. Has formed.

The upper end of the reinforcing layer 11 is located above the end J of the bead apex 6 and below the end L of the folded portion 9b. The lower end of the reinforcing layer 11 is located in a lower region X of a regulated range near the bead core 5 described later.

As shown in FIG. 3, the reinforcing layer 11 has a steel cord 19 extending vertically in the tire radial direction as shown in the lower half of FIG. α, preferably 65-75 °
The cords 19 are arranged in an inclined manner in the direction of rotation of the tire at the inclination angle α, and form an annular sheet formed by covering these cords 19 with topping rubber.

When the tire is mounted on a standard rim RM and is loaded with a normal internal pressure, the reinforcing layer 1
1 is a radially outer end O of the bead core 5.
An outer line Y parallel to the tire axis passing through an outer point P separated by a distance of 0.067 times the cross-sectional height H from an inner surface Z and an inner line Z parallel to the tire axis passing through a radially inner end Q of the bead core. Are located in a lower region X sandwiched between the two.

The outer end K in the radial direction of the reinforcing layer 11 has a radius HA of 0.045 times or more and 0.1 times or less the tire sectional height H from the tip J of the bead apex 6 in the unloaded state. It is located at a position separated outward in the direction.

Further, the tip L of the folded portion 9b of the first carcass ply 9 has a distance H not less than 0.045 times and not more than 0.1 times the tire sectional height H from the outer end K of the reinforcing layer 11.
B is located at a position radially outwardly separated.

The belt layer 8 includes a plurality of belt plies 8a in which organic fibers such as nylon, rayon, and aromatic polyamide fibers or steel cords are arranged at an angle of 15 to 30 ° with respect to the tire equator C. In this example, two treads are formed so as to increase the rigidity of the tread portion 2.

In the present embodiment, the reinforcing rubber layer 12 is formed of a reinforcing rubber ply of a sheet body, and its rubber hardness is desirably 60 to 90 degrees in JISA hardness. Rubber hardness is 60
If it is less than 10 degrees, a sufficient reinforcing effect cannot be obtained and the rubber hardness is 9
If the angle exceeds 0 degree, peeling is likely to occur at the boundary surface between the reinforcing rubber layer 12 and the surrounding members, which is not preferable.

Further, the reinforcing rubber layer 12 has a radially inner end portion having an overlapping portion M which overlaps the folded portion 9b of the first carcass ply 9 by 5 mm or more, and a radially outer end portion of the belt layer 8 having the overlapping portion M. It has an outer overlapping portion N which overlaps with an overlapping margin of 5 to 25 mm. If the overlap allowance at the inner and outer overlap portions M and N is less than 5 mm, there is a risk that stress concentrates at each end of the reinforcing rubber layer and edge loose occurs, and the overlap allowance at the outer overlap portion N is reduced. If it exceeds 25 mm, the tire weight increases and fuel efficiency increases.

As shown in FIG. 4, the first carcass ply 9 has a rubber thickness T between the carcass cord of the main body 9a of the first carcass ply 9 and the carcass cord of the second carcass ply. It is preferable that the diameter be in the range of 0.25 times or more and 4.0 times the diameter d of the carcass cord 20.

When the rubber thickness T is less than 0.25 times the diameter d, a sufficient reinforcing effect is not exhibited, and when it exceeds 4.0 times, heat generation becomes large at the time of load rolling.

The reinforcing rubber layer 12 is disposed in a region where the folded portion 9b of the first carcass ply 9 and the reinforcing layer 11 and the bead apex 6 do not exist in the side wall portion 3. By reinforcing with the reinforcing rubber layer, the rigidity of the sidewall portion 3 can be equalized and the rigidity of the tire can be further increased, and high performance can be exhibited in a circuit running where high rigidity of the tire is required.

In this embodiment, a band layer 16 is provided on the tread portion 2 outside the belt layer 15. Band layer 1
Reference numeral 6 denotes a band ply 16a which covers the entire surface of the belt layer 15, and a band ply 16b which is disposed outside the band ply and which has a small width and which reinforces both ends of the belt layer 15.

Each of the inner and outer band plies 16a and 16b is a long one in which one or more organic fiber cords such as nylon and aromatic polyamide fibers are covered with topping rubber.
It is formed by spirally winding a narrow band ply in the circumferential direction of the tire to prevent lifting of the belt layer 15 during high-speed running, enhance high-speed performance, and prevent peeling of the end portion of the belt layer 8 to withstand high load. Enhance performance and durability.

It should be noted that the band layer 16 can be formed by one band ply having a full width and covering the entire surface of the belt layer. Alternatively, two band plies having the full width may be formed by overlapping.

In the tread portion 2, a tread rubber layer 18 is disposed radially outside the band layer 16. The tread rubber layer 18 is provided outside the band layer 16 and the band layer 16.
And an inner layer 21 disposed adjacent to the outer layer 22 and an outer layer 22 forming a tread surface outside the inner layer 21.

The inner layer 21 is made of JISA to enhance the ride comfort.
The outer layer 22 is made of a hard rubber having a hardness of 50 to 60 degrees and has a cushioning property. The outer layer 22 is made of a hard rubber having a hardness of 62 to 72 degrees according to JISA to improve the wear resistance of the tread surface. I have.

[0040]

A) Test 1 A tire having the structure shown in FIG. 1 except that the tire size is 225/50 ZR16 and the reinforcing rubber layer 12 is not provided, according to the specifications shown in Table 1 and the inclination of the cord of the reinforcing layer 11 Prototypes of the configuration (Example 1) and configurations (Comparative Examples 1 to 3) other than the configuration of the present application were respectively manufactured, and the performance was compared for steering stability.

In the test of the steering stability, the test tires were mounted on a 3000 cc class sports car, traveled on a paved road surface, determined by the driver's feeling, and the index was set to 100 according to Example 1.
The higher the value, the better. Table 1 shows the test results.

[0042]

[Table 1]

As a result of the test, the first embodiment according to the configuration of the present invention was performed.
It was confirmed that the sample had better steering stability than Comparative Examples 1 to 3.

B) Test 2 The steering stability was compared depending on the presence or absence of the reinforcing rubber layer. The steering stability was compared between a tire (Example A) having the same size as that of Test 1 and having the configuration shown in FIG. 1 (Example A) and a tire (Example B) without the reinforcing rubber layer in FIG.

In the test, the vehicle was mounted on the same vehicle as in the test 1, the vehicle was run on a pavement, and the driving stability was determined based on the driver's feeling.
It was indicated by an index. The higher the value, the better.

Further, at the time of the running test, the lap time per one lap was measured for ten consecutive laps, and the average value was compared. Table 2 shows the test results.

[0047]

[Table 2]

As a result of the test, it was confirmed that the provision of the reinforcing rubber layer further improved the steering stability, and particularly exhibited its performance in circuit running.

C) Test 3 Further, the effect of the position of the outer end K and the position of the inner end D of the reinforcing layer 11 on the durability was tested. The tire size, the tire configuration, and the main structure of the tire are substantially the same as those in Test 1, and a tire having the specifications shown in Table 3 (Example A) and a tire not having the configuration of the present application (Comparative Examples A and C) are prototyped. A comparison was also made of their performance.

In the test, a drum test machine having a diameter of 1707 mm was used, an internal pressure of 2.5 kg / cm ² and a load of 1100 kg were applied, and the vehicle was run 5000 km at a speed of 60 km / h to check for damage. Table 3 shows the test results.

[0051]

[Table 3]

As a result of the test, it was confirmed that the example A according to the configuration of the present invention had better durability than the comparative examples A and C.

[0053]

As described above, the pneumatic tire of the present invention has the following features.
By providing the above configuration, the steering stability can be increased and the durability can be improved, and economical production of tires that are easy to mold and have good force variation becomes possible, and particularly, very hard sports around the suspension. It can be suitably used for high-performance vehicles such as cars.

When the reinforcing rubber layer having the above structure is provided, the rigidity of the sidewall portion can be uniformly increased, and high performance can be exhibited even on a circuit.

[Brief description of the drawings]

FIG. 1 is a right half sectional view of a tire showing one embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a main part thereof.

FIG. 3 is a left half front view showing an example of a reinforcing layer.

FIG. 4 is a sectional view showing a reinforcing rubber layer together with a carcass.

FIG. 5 is a sectional view showing a conventional technique.

[Explanation of symbols]

 Reference Signs List 2 Tread portion 3 Side wall portion 4 Bead portion 5 Bead core 6 Bead apex 6a Outward surface 7 Carcass 8 Belt layer 9 First carcass ply 9a Body portion 9b Turnback portion 10 Second carcass ply 11 Reinforcement layer 12 Reinforcement rubber layer 19 Code BL Bead baseline C Tire equator D Inner end of reinforcing layer d Diameter of carcass cord H Tire section height J Tip of bead apex K Outer end of reinforcing layer L Tip of folded part M Inner overlapping part N Outer overlapping part P Outside Point Q Radial inner end of bead core R Tire radius line RM Rim T Rubber thickness X Lower area Y Outer line Z Inner line α Fall angle

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location B60C 15/00 B60C 15 / 00H (56) References JP-A-2-24205 (JP, A) JP-A-2-34410 (JP, A) JP-A-2-310110 (JP, A) JP-A-5-58121 (JP, A) JP-A-61-287804 (JP, A) JP-B-56-21603 (JP, B2) Japanese Patent Publication No. 7-12765 (JP, B2) Patent 2613102 (JP, B2)

Claims (2)

(57) [Claims] An outer surface of a bead apex which is folded from inside to outside around a bead core of the bead portion and extends upward from the bead core is provided on a body portion extending from a tread portion to a bead portion through a sidewall portion. A first carcass ply having a folded portion of a high turn-up structure and a lower end of the outward surface of the bead core passing from the tread portion to the sidewall portion, passing between the folded portion and the outward surface of the bead apex. A carcass comprising a second carcass ply having a lower end interrupted in the vicinity, a belt layer disposed inside the tread portion and outside the second carcass ply, and a carcass ply including the second carcass ply and the first carcass ply. Between the turn-up portion and the tire radially extending up and down in the tire radial direction and the outer end of the radial direction is 60 to 80 ° with respect to the tire radial line. In addition to the reinforcing layer consisting of a ply using a steel cord that tilts in the direction of rotation of the tire in degrees, the bead apex has a bead base at its tip J in a no-load state where the rim is assembled and filled with a normal internal pressure. The height from the line is not less than 0.3 times and not more than 0.5 times the tire cross-section height H, and the radially inner end D of the reinforcing layer is located at the cross-sectional height H from the radially outer end of the bead core. An outer line Y parallel to the tire axis passing through an outer point P radially outwardly extending a distance of 0.067 times of the following, and an inner line Z parallel to the tire axis passing a radially inner end Q of the bead core. Is located in the lower region X sandwiched therebetween, and the radially outer end K of the reinforcing layer is radially outwardly separated from the tip end J of the bead apex by a distance of at least 0.045 times the tire section height H. Position On the other hand, the front end of the folded portion of the first carcass ply is positioned at a position radially outward at least 0.045 times the tire section height H from the outer end K of the reinforcing layer. A pneumatic tire characterized by being made to have. 2. The carcass has a reinforcing rubber layer made of a reinforcing rubber ply interposed between a main body portion of the first carcass ply and a second carcass ply, and the reinforcing rubber layer has a radial inner portion. The first carcass ply has an inner overlapping portion overlapping the folded portion of the first carcass ply by 5 mm or more at an end portion, and an outer overlapping portion overlapping the belt layer by 5 to 25 mm at a radial outer end portion, and The rubber thickness T between the carcass cord of the main body portion of the ply and the carcass cord of the second carcass ply is not less than 0.25 times and not more than 4.0 times the diameter of the carcass cord of the first carcass ply. The pneumatic tire according to claim 1, wherein: