JP2001121929A - Corrugated runflat tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a runflat comfortable at riding at the time of normal status having internal pressure filled to improve durability at the time of being punctured. SOLUTION: On a side part of tire, protruding parts 12 having a carcass ply bulged annularly outside a tire rotation axial direction and recessed parts 13 are lined alternately to arrange to be a corrugated shape by a tire sectional view such that the protruding parts are positioned at upper and lower ends of the side part. An inner reinforced rubber pad 7 with crescent-shaped cross section is filled between the protruding part of the carcass ply and an inner liner 4. An outer reinforced rubber pad 8 with crescent-shaped cross section is filled between the recessed part 13 of the carcass ply and a side wall rubber 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire capable of continuing running even when internal pressure is released due to a puncture or the like while being mounted on an automobile and running, that is, a so-called run flat tire.

[0002]

2. Description of the Related Art Normally, when a tire is mounted on a car and running, the internal pressure is released due to puncture and the like, and the running is continued as it is, the tire is largely deformed at every contact with the ground and comes off the rim, or the inner surface of the tire crown portion and side surfaces are removed. If the steering wheel is taken off due to the tire being destroyed due to the heat generated due to contact and friction with the lower part of the part, there is a danger if the vehicle continues running with the internal pressure released. Therefore, as shown in FIG. 2, a fiber reinforcing layer 15 in which cords are arranged is provided near the inner surface of the side portion, and a reinforcing pad rubber 16 having a substantially crescent cross section is disposed between the fiber reinforcing layer and the carcass ply 2. A run-flat tire has been proposed in which the rigidity of the portion is increased so that it does not bend significantly even when the internal pressure is released. Tires with this structure
Since the durability in a state where the internal pressure is released (hereinafter, a state in which the internal pressure is released is referred to as a punctured state) is low, the carcass ply needs to be
A run-flat tire has been proposed in which reinforcing pad rubber is disposed between the layers and between the inner layer and the inner liner to increase the load supporting ability of the side portion in a punctured state. (JP-A-6-191244 and JP-A-7-215023)

In the run flat tire having the above structure, a reinforcing rubber pad is disposed on a side portion to increase the longitudinal rigidity so that the side portion does not bend significantly in a punctured state.
The riding comfort is poor in the normal state where the internal pressure is filled, and in the puncture state, the reinforcing rubber pad is compressed in the radial direction every time it touches the ground and spreads in the direction of the rotation axis, so stress in the compression direction acts on the cord located inside and the cord However, due to early fatigue, the durability in the punctured state is low, and the run flat tire performance has not reached a satisfactory level. In addition, since the initial deflection is small, even if the vehicle is punctured, it is difficult for the driver to detect the puncture, and there is a problem that the vehicle continues traveling at high speed. Generally, cords have good fatigue resistance to repeated stress in the tensile direction, but are poor in the compressive direction.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a run-flat tire having a good ride comfort in a normal state where the internal pressure is charged and an improved durability performance in a punctured state. Things.

[0005]

According to the present invention, if the side portion is constituted by a plurality of curves to disperse the bending and the side portion is not provided with a cord layer which generates a stress in the compression direction in a punctured state, the run is improved. Flat performance is improved.

According to the present invention, a large number of cords are reinforced by a carcass ply arranged at right angles in the tire circumferential direction, an outer surface of a side portion is made of sidewall rubber, an inner surface is made of an inner liner, and a cross section is formed inside the side portion. In a run flat tire in which a belt and tread rubber are laminated on a crown portion of a carcass having a crescent-shaped reinforcing rubber pad, the carcass ply expands annularly outward in the tire rotation axis direction at a side portion when viewed in a tire cross section. The protruding tip has an arcuate convex portion and the concave bottom has an arcuate concave portion alternately connected to form a wavy shape, the upper end of the side portion transitioning from the crown portion to the side portion and the lower end of the side portion transitioning from the side portion to the bead portion. The cross section of the size that the cross section of the tire side portion is also wavy between the convex portion of the carcass ply and the inner liner is arranged so that the convex portion is located at A crescent-shaped inner reinforcing rubber pad is filled, and a cross section between the concave portion of the carcass ply and the side wall is filled with a substantially crescent-shaped outer reinforcing rubber pad.The cross section of the side portion also has a waveform corresponding to the wave shape of the carcass ply. It is a wavy run flat tire.

[0007]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a run flat tire according to one embodiment of the present invention. Reference numeral 1 denotes a carcass, and 2 denotes a carcass ply. A large number of cords are arranged in the circumferential direction of the tire and both sides are covered with rubber, and a carcass ply 2 for reinforcing the carcass 1 has a convex portion 12 bulging annularly outward in the tire axial direction at a side portion of the tire. The recesses 13 which are annularly depressed toward the tire are alternately arranged so as to form a substantially wavy shape when the cross section of the tire is viewed, and are wound up around the bead core 6 from the inside toward the outside, and extend upward to form the winding portion 3.
And terminates in the side portion. The protruding portion 12 of the carcass ply 2 is located at the upper end of the portion that transitions from the crown portion to the side portion and at the lower end of the portion that follows the bead portion from the side portion.
The bottom of 3 is an arc. The inner surface of the carcass 1 is formed of the inner liner 4, and the outer surface of the side portion is formed of the sidewall rubber 5. The inner reinforcing pad rubber 7 having a substantially crescent cross section between the convex portion 12 of the carcass ply and the inner liner 4.
Is filled between the recess 13 of the carcass ply and the sidewall rubber 5 with the outer reinforcing pad rubber 8 having a substantially crescent cross section, and the bead filler 9 is filled between the carcass ply and the winding portion 3. The shapes of the inner reinforcing pad rubber 7 and the outer reinforcing pad rubber 8 are bulged and depressed corresponding to the convex and concave portions of the carcass ply, so that the cross section of the side portion is also wavy. The radius of curvature of the bottom is set to be 70 mm or less. Inner reinforcement pad rubber 7
The outer reinforcing pad rubber 8 is formed of a rubber composition having a high elastic modulus and a low heat generation. Both may be the same rubber composition or may be different. The bead filler 9 is formed of a rubber composition usually used for a bead filler of a tire. A belt 10 is provided adjacent to the crown portion of the carcass ply 2, and a tread rubber 11 is provided so as to cover the belt 10.

As the carcass ply, a cord generally used for a tire is used, and examples thereof include polyester cord, nylon cord, aramid cord, and steel cord.
Among them, polyester cords having good fatigue resistance, high elastic modulus, and small heat shrinkage are preferred. The carcass ply is formed of one or a plurality of cord layers in which a large number of the cords are arranged. As the rubber used for the reinforcing rubber pad, a rubber generally used for a tire is used, and examples thereof include natural rubber, SBR, BR, and IR.

In the run flat tire of the present invention, even if the side portion is hardly deformed due to the arrangement of the reinforcing rubber pad, the side portion is constituted by a plurality of curves, so that the radial distortion when grounded is reduced. Since the tires are dispersed in the individual curved portions, the tire is easily bent as a whole, and the riding comfort is better than that of a conventional run-flat tire having one curved side portion. Since the reinforcing rubber pad is arranged on the concave side of the curved portion of the carcass ply, the stress acting on the carcass ply even in the punctured state becomes a tensile stress in all the portions of the carcass ply, and the stress in the compression direction acts. Since there is no cord layer that fatigues early, the durability is improved.

[0010]

EXAMPLE A tire size 285 / 70R having a sectional structure shown in FIG. 1 using a polyester cord for a carcass ply.
A run flat tire corresponding to 15 was prototyped. A test run flat tire and a conventional run flat tire having the cross-sectional structure shown in FIG. 2 were filled with a predetermined internal pressure to perform a longitudinal rigidity test. The results are shown graphically in FIG. The solid line in FIG. 3 shows the relationship between the vertical load and the vertical deflection of the tire having the structure shown in FIG. 1, and the broken line shows the relationship between the vertical load and the vertical deflection of the tire having the structure shown in FIG. Next, the vehicle is mounted on a passenger car, and is filled with a predetermined internal pressure.
Sensory tests were performed on the noise performance, ride comfort, steering stability performance, feeling of response, and wandering in each state by running alternately. For comparison, a sensory test of the above-described performance in a state where a predetermined internal pressure is filled between a run flat tire having a structure shown in FIG. 2 (hereinafter, a run flat tire having a structure shown in FIG. 2 is referred to as a structural tire shown in FIG. 2) and a normal tire And the sensory test of the said performance in the flat state of FIG. 2 structure tire was performed. The results are shown in Table 1 as ◎ if the average of the evaluations of the five drivers is significantly better than that of the structural tire shown in FIG. 2, ○ if it is excellent, △ if they are equivalent, and × if they are inferior.

[0011]

[Table 1]

The run flat tire having the structure shown in FIG. 1 and the tire having the structure shown in FIG. 2 were subjected to a durability test in a punctured state by the following method. The results are shown in Table 1 by an index with the structural tire in FIG.

Endurance test method The rim is assembled and set to a drum test machine in a state where the internal pressure is filled. After applying a load of 85% of the maximum load, the internal pressure is reduced to start running, and the tire is broken at 80 km / h. I ran until. The result was shown by an index calculated by the following equation. The larger the value, the better. (Running time of the example tire) × 100 / (running time of the structural tire in FIG. 2)

The following can be seen from Table 1. That is, the performance of the run-flat tire of the present invention whose cross-sectional structure is shown in FIG. 1 when filled with a predetermined internal pressure is almost the same as that of a normal tire except for a feeling of response and noise performance. The ride comfort is better than that of the conventional run flat tire shown in FIG. 2, the steering stability is inferior, and the others are equivalent. In a punctured state, the run flat tire of the present invention has better noise performance, ride comfort, and durability than the structural tire shown in FIG. 2, and has the same responsiveness and wandering property.

[0015]

According to the present invention, the carcass plies are arranged so that the convex portions protruding annularly in the direction of the rotation axis at the side portions and the concave portions are alternately connected to form a wavy shape when the tire cross section is viewed. By adopting a structure in which a reinforcing pad rubber with a cross section of approximately crescent shape is arranged on the back side of the part protruding outward or inward in the direction of the rotation axis of the wavy shape, radial distortion due to load can be reduced in each curved part of the wavy shape Even if the reinforcing pad rubber is arranged on the side portion and the rigidity is increased, the tire as a whole is easily bent and the riding comfort is improved.
Also, in the puncture state, the stress acting on the carcass ply is made to act in the tensile direction in all parts of the carcass ply, so that the stress in the compression direction that causes the cord to fatigue at an early stage does not act. This has the effect of improving the durability of the device.

[Brief description of the drawings]

FIG. 1 is a sectional view of a run flat tire according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a run-flat tire having a conventional structure.

FIG. 3 is a diagram illustrating a relationship between a vertical load and a vertical deflection when a predetermined internal pressure is filled.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carcass 2 Carcass ply 4 Inner liner 5 Sidewall rubber 7 Inner reinforcing pad rubber 8 Outer reinforcing pad rubber 9 Bead filler 10 Belt 11 Tread rubber 12 Carcass ply convex part 13 Carcass ply concave part 14 Wavy curved part of tire side part

Claims (2)

[Claims] 1. A carcass ply consisting of a number of cords arranged at right angles in the tire circumferential direction, reinforced by a carcass ply, an outer surface of a side portion is made of sidewall rubber, an inner surface is made of an inner liner, and a crescent-shaped cross section is formed inside the side portion. In a run flat tire in which a belt and a tread rubber are laminated on a crown portion of a carcass on which a reinforcing rubber pad is arranged, in a side portion, a carcass ply bulges annularly outward in the tire rotation axis direction, and a cross section at the tip thereof has a convex portion with a circular arc. The bottom of the tire is alternately connected with the concave part of the arc, and the tire is arranged in a wave shape in cross section of the tire such that the convex part is located at the upper end and the lower end of the side part. The cross section of the tire part between the convex part of the carcass ply and the inner liner An inner reinforcing rubber pad with a cross section of approximately crescent shape, which is also wavy, is provided between the recess of the carcass ply and the side wall. Waveform run-flat tire, characterized in that filled with strong rubber pad. 2. The wavy run-flat tire according to claim 1, wherein the radius of curvature of the wavy curved portion of the carcass whose side portion is wavy corresponding to the cross-sectional waveform of the carcass ply is 70 mm or less.