JPH05270215A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a pneumatic tire, with which the maneuvering stability and the comfort in car cabin so far incompatible according to the conventional technique are enhanced relatively by inserting reinforcing layers appropriately. CONSTITUTION:Reinforcing layers 5a, 5b are arranged in the bead parts 4a, 4b of a pneumatic tire to be mounted on a wheel of asymmetrical structure being offset to the wheel front, wherein the arrangement meets the condition E1/E2<=0.8, where E1 is the cord modulus of the reinforcing layer 5a to be inserted to the bead part 4a mounted on the rim end Ra on the disc part offset side while E2 is the cord modulus of the other 5b to be inserted to the other bead part 4b mounted on the rim end Rb on the counter-offset side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air in which at least one of steering stability and riding comfort, which are in a contradictory relationship, is relatively improved by appropriately inserting a reinforcing layer as compared with the conventional air. Containing tires.

[0002]

2. Description of the Related Art Recent pneumatic tires are strongly required to further improve not only running performance such as steering stability but also riding comfort. The riding comfort of this tire is represented by the impact value and noise level of the vibration that is brought into the vehicle from the road surface through the tire.The transmission path of the vibration to the vehicle is the tread portion of the tire, It is designed to be transmitted to the vehicle body through the side wall, the left and right beads, and the rim / disc.

By the way, as a conventional general method for improving the steering stability of a pneumatic tire, there is a method of inserting a cord reinforcing layer from a bead portion to a sidewall portion. However, when the reinforcing layer is inserted in this way, the lateral rigidity and circumferential rigidity of the sidewall portion are increased, so that the steering stability is improved, but on the other hand, the vertical rigidity is also increased and the reaction force against the external force received from the road surface is increased. Therefore, the problem that the riding comfort is deteriorated cannot be avoided.

On the other hand, along with the recent front-wheel drive (FF) of vehicle drive system and expansion of vehicle interior space, asymmetrical structure for advancing the rear space of the wheel structure as much as possible has been advanced, and the disc portion is connected to the rim. The amount by which the position is offset from the center of the rim width to the wheel front side is gradually increasing. As a result of research on the relationship of vibration transmission between the wheel having such an asymmetric structure and the tire, the present inventors have found that there is a very strong correlation between the two.

That is, when the vibration transmissibility transmitted from both side wall portions of the tire to the wheel having the asymmetric structure is examined, the transmissibility of vibration passing through the rim end on the disk offset side (wheel front side) is It is greater than the transmissibility of vibration that passes through the rim end on the anti-offset side (the back side of the wheel), and this tendency becomes more pronounced as the distance by which the coupling position of the disc portion is offset from the center of the rim width increases. I understood.

The inventors of the present invention have made a detailed study of such new knowledge in relation to the steering stability. As a result, if they are skillfully used, the steering stability and the riding comfort which are in the antithetic relationship as described above are improved. Therefore, it has been found that the above problem can be solved and at least one of them can be improved without deteriorating both performances.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to properly insert a reinforcing layer so that at least one of steering stability and riding comfort, which are in a trade-off relationship, does not deteriorate, and at least one of them is compared with a conventional one. It is to provide a pneumatic tire that is relatively improved.

[0008]

A pneumatic tire according to the present invention is a pneumatic tire mounted on a wheel in which a connecting position of a disc portion to a rim is offset from a rim width center to a wheel front side. The same number of reinforcing layers made of a cord material and having substantially the same number of cord ends are arranged in the right and left bead portions, respectively, and the cord modulus E _{1 of the} reinforcing layer is inserted into the bead portion mounted on the rim end on the offset side of the disc portion. And a cord modulus E _{2 of the} reinforcing layer to be inserted into the bead portion mounted on the rim end on the anti-offset side have an asymmetric structure in which E ₁ / E ₂ ≦ 0.8. It is a thing.

Since the reinforcing layer is arranged in the bead portion as described above, the lateral rigidity and the peripheral rigidity of the sidewall portion are increased and the steering stability can be improved. Moreover, when the reinforcing layer is arranged on the bead portion, the cord modulus E _{1 of the} reinforcing layer to be inserted into the bead portion mounted on the rim end on the disc offset side (wheel front side) and the rim end on the opposite offset side are arranged. By setting the ratio E ₁ / E ₂ with the cord modulus E ₂ of the reinforcing layer to be inserted into the mounted bead portion to be 0.8 or less, the rim end on the offset side of the disc portion having a large vibration transmissibility is set. It is possible to reduce the amount of vibration transmitted by reducing the rigidity of the sidewall portion on the bead portion side mounted on the vehicle, and to reduce the impact force and noise on the vehicle interior. On the other hand, the rigidity of the sidewall on the bead side, which is attached to the rim end on the anti-offset side of the disc with a small vibration transmissibility, is the same as the conventional one or more, and if it is more than that, the steering stability provided by inserting the reinforcing layer The running performance such as the property is not substantially reduced. Therefore, by properly inserting the reinforcing layer as described above, it is possible to relatively improve at least one of the steering stability and the riding comfort, which are in a contradictory relationship, as compared with the related art.

In the present invention, the reinforcing layer to be arranged in the bead portion is a rubberized reinforcing layer composed of fiber cords such as nylon fiber, polyester fiber, rayon fiber, aromatic polyamide fiber, glass fiber, carbon fiber or steel cord. Is preferably used. In the present invention, the cord modulus E ₁ , E ₂ of the reinforcing layer means the force per unit area (Kgf) required when pulling the cord by 2%.
/ Mm ² ) and refers to the initial tensile resistance (apparent Young's modulus) measured according to JIS L1017. In the present invention, the cord modulus E ₁ and E ₂ can be set asymmetrical as described above by making the cord material of the reinforcing layer different between the disc offset side and the anti-offset side. Even when the cord material of the reinforcing layer is the same, it is possible to change the apparent Young's modulus by changing the twist number of the cord, the dipping condition or the modulus of the coat rubber. The cord moduli E ₁ and E ₂ of this reinforcing layer are set so that E ₁ / E ₂ ≦ 0.8, but if E ₁ / E ₂ > 0.8, the asymmetric structure is insufficient. This is because the riding comfort is deteriorated or the effect of the present invention cannot be obtained.

FIG. 1 shows a tire mounted on a wheel according to an embodiment of the present invention. In FIG. 1, W is a wheel fixed to the axle O, and T is a pneumatic tire mounted on the wheel W. The wheel W is composed of a rim R and a disc portion D, and the disc portion D has an asymmetrical structure in which the rim R is offset and fixed to the wheel front side (A side) from the rim width center C by a distance e. ..

The pneumatic tire T includes a tread portion 1, left and right sidewall portions 3a and 3b, and bead portions 4a and 4b.
The bead portions 4a and 4b are mounted on the rim R of the wheel W. Left and right bead portions 4a,
Reinforcing layers 5a and 5b are respectively arranged on 4b, and the lower ends of these reinforcing layers 5a and 5b are inserted to the inside of the rim flange, and the upper ends thereof are sidewall portions 3a and 3b.
It is inserted so as to extend to b. These reinforcing layers 5a and 5b
Is inserted, the rigidity of the sidewall portions 3a, 3b is increased, and the steering stability of the tire is improved.

When the reinforcing layers 5a and 5b are inserted as described above, the reinforcing layer 5 arranged on the bead portion 4a on the front side A of the wheel.
The cord modulus E _{1 of a} is smaller than the cord modulus E ₂ of the reinforcing layer 5b arranged on the bead portion 4b on the back side B of the wheel, and the ratio E ₁ / E ₂ is 0.8 or less. .. By adjusting the cord moduli E ₁ and E ₂ of the left and right reinforcing layers 5a and 5b in this way, the vibration transmissibility of the sidewall portion 3a attached to the rim end Ra on the wheel front side A can be increased. Since it is smaller than the vibration transmissibility of the sidewall portion 3b attached to the end Rb, the steering stability brought about by these reinforcing layers 5a and 5b is maintained, and the steering stability and the riding comfort in a contradictory relationship are maintained. At least one of them should be improved relative to the conventional one.

The tire of the above-mentioned asymmetric structure of the present invention is
In order to achieve the intended effect by combining with the wheel of asymmetric structure, indicate which side should be mounted on the front side of the rim (wheel front side) and the rim offset amount of the compatible wheel on the side wall surface. Is desirable. For example, "" Front side when mounted ", compatible rim offset: 30-40 mm", "" SIDE F
ACING OUTWARDS, RIM OFFSE
"T: 30-40 mm""is displayed. The size and shape of the characters are arbitrary, but 0.
3 to 6 mm so that it protrudes from the tire surface,
In the case of a concave character, it can be engraved at a depth of about 0.3 to 1 mm, or a rubber sheet on which a display character is transferred can be attached to a green tire to be integrated during vulcanization. Further, in order to make the display more conspicuous, it is also possible to provide a platform projecting from the tire surface by about 1 to 3 mm and to display convex characters or concave characters on it.

[0015]

EXAMPLES Pneumatic tires each having a tire size of 175 / 70R13 and made of Example 1, Conventional Examples 1 and 2 and Comparative Example 1 as shown below were manufactured. Example 1: 60 mm height from the bead heel, 50 mm width, and cord modulus 300 on the bead portion on the wheel front side
Kgf / mm ² reinforcement layer is inserted, the height of the bead heel from the bead heel is 60 mm, and the width is 50 mm.
Tire with a reinforcing layer having a cord modulus of 700 Kgf / mm ² . Conventional Example 1: A tire having no reinforcing layer on the left and right beads. Conventional Example 2: Height from the bead heel to the left and right bead parts 6
0 mm, width 50 mm, cord modulus 500 Kgf /
Tires with each mm ² reinforcement layer inserted. Comparative Example 1: At the bead portion on the wheel front side, the height from the bead heel is 60 mm, the width is 50 mm, and the cord modulus is 700.
Kgf / mm ² reinforcement layer is inserted, the height of the bead heel from the bead heel is 60 mm, and the width is 50 mm.
Tire with a reinforcing layer having a cord modulus of 300 kgf / mm ² .

Each of these four types of tires was rim-assembled to an asymmetric wheel (rim size: 13 × 5JJ, rim offset amount: 35 mm), and the following protrusion overriding test, actual vehicle road noise test and steering stability test were conducted. Table 1 shows the results of the bump overhang test and the steering stability test.
In addition, the results of the road noise test of an actual vehicle are shown in FIG. Protrusion pass test : A running test was conducted on a drum having a drum diameter of 1707 mm provided with a protrusion of 5 mm under the conditions of an air pressure of 2.0 kgf / cm ² , a load of 200 kg, and a speed of 50 km / hr. The difference between the maximum value and the minimum value of kgf) (the greater the difference, the worse the riding comfort) was measured and evaluated. The evaluation results are shown by an index based on the value of Conventional Tire 1 (100). The larger the index value, the better the riding comfort. Actual vehicle road noise test : Tire internal pressure 2.0 kgf / cm
^{2. On} an FF vehicle with a displacement of 1.6 liters, place a microphone at the position of the driver's seat window side ear when traveling on a rough road surface at a speed of 50 km / hr, and set the sound pressure [dB (A )] Was measured and evaluated. FIG. 4 shows the result of the 1/3 octave analysis. The larger the sound pressure value is, the louder the passenger compartment is and the more the noise is significant. Steering stability test : A slalom test road in which pylons are set up at regular intervals is actually driven by the same vehicle as in the actual vehicle road noise test, and the steering stability is evaluated by the average speed, and the value of the conventional tire 1 is used as a standard ( It is indicated by an index of 100). The larger the index value, the better the steering stability.

[0017] As is apparent from Table 1, the tire of Example 1 of the present invention has significantly improved steering stability as compared with the tire of Conventional Example 1, and the impact force in the front-rear direction when passing over the protrusion is slightly increased. It can be seen that there is virtually no difference in riding comfort just by being present. On the other hand, the tire of Conventional Example 2 has improved driving stability but has poor riding comfort. The tire of Comparative Example 1 is a tire obtained by backlining the tire of Example 1, and although the driving stability is improved, the riding comfort is obviously reduced. Further, as is clear from FIG. 2, the tire of Example 1 was able to reduce road noise as compared with the tires of Conventional Example 2 and Comparative Example 1 in which the reinforcing layer was provided.

Next, the tire size is changed to 175 / 70R13.
And, except that the points of reinforcing layers were inserted in common on the left and right beads, the cord angle of this reinforcing layer, the number of cord ends, the height from the bead heel, the cord material, the cord twist structure, and the initial tensile resistance ( Code examples), the conventional examples 3 to 6 in which the code modulus is different as shown in Table 2,
Steel radial tires of Examples 2 to 5 and Comparative Example 2 of the present invention were manufactured. The cord twist structure of Table 2 shows the denier in the upper part of the organic fiber cord and the number of S × Z twists per 10 cm in length in the lower part, and the steel cord shows the twist structure in the upper part and the twist pitch in the lower part. is there.

Each of these nine types of tires was rim-assembled to an asymmetric wheel (rim size: 13 × 5JJ, rim offset amount: 35 mm), and a projection ride-over test and a steering stability test were conducted in the same manner as above to obtain riding comfort and The steering stability was evaluated. The results are shown in Table 2 by an index with the value of Conventional Tire 3 as the reference (100).

[0020]

As is clear from Table 2, the tires of Examples 2 to 4 of the present invention maintain the same riding comfort as the tire of Conventional Example 3 using the 66 nylon cord, while being more stable in handling. It can be seen that the sex is improving. Further, the tire of Example 5 of the present invention maintains the riding comfort equivalent to that of Conventional Examples 4 and 5 using the polyester cord or the aramid cord, and has the same steering stability as that of Conventional Example 6 using the steel cord. You can see that it has been realized. On the other hand, in the tire of Comparative Example 2, the difference in cord modulus between the reinforcing layers on both sides of the wheel was small, and the result was equivalent to that of the tire of Conventional Example 3.

[0022]

As described above, according to the present invention,
Odor for pneumatic tires mounted on symmetrical wheels
Of the disc section when placing the reinforcement layer on the bead section.
Before inserting into the bead that is attached to the rim end on the fuss side
Reinforcing layer cord modulus E ₁And on the anti-offset side
The core of the reinforcing layer to be inserted into the bead part attached to the rim end.
Modulus E₂And E₁/ E₂≦ 0.8
Discs with a high vibration transmissibility
Of the bead that is attached to the rim end on the offset side
Dwall rigidity is reduced and the tires and wheels
The amount of vibration transmitted to the vehicle body by
Driving stability and riding comfort in
The relative performance of at least one
Can be improved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a pneumatic tire according to an embodiment of the present invention mounted on a rim.

FIG. 2 is a graph showing the relationship between frequency and sound pressure in a pneumatic tire.

[Explanation of sign]

1 tread part 3a, 3b sidewall part 2a, 2b bead part 5a, 5b reinforcing layer T tire W wheel R rim D disk part e offset distance

Claims (1)

[Claims] 1. A pneumatic tire mounted on a wheel in which a connecting position of a disc portion to a rim is offset from a center of a rim width to a wheel front side, and substantially the same in the left and right bead portions of the pneumatic tire, which are made of a cord material. The same number of reinforcing layers as the number of cord ends are arranged, and the cord modulus E _{1 of the} reinforcing layer to be inserted into the bead portion mounted to the rim end on the offset side of the disc portion, and the bead mounted to the rim end on the anti-offset side. The cord modulus E _{2 of the} reinforcing layer to be inserted in the portion is set to E ₁ / E ₂ ≦ 0.
A pneumatic tire having an asymmetric structure in the relationship of 8.