JP2022033616A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire that exerts excellent low rolling-resistant performance while maintaining cut-resistant performance.SOLUTION: A pneumatic tire 1 includes: a side wall part 3; a pair of bead parts 4 in which bead cores 5 are embedded, respectively; a carcass that straddles bead cores 5; and a reinforcement layer that is arranged on the tire-radial-direction outside of the carcass and in the side wall part 3. The reinforcement layer includes a discontinuous reinforcement layer in which cord strips 9 having a plurality of arranged reinforcement cords 9c are arranged at mutual intervals in a tire circumferential direction.SELECTED DRAWING: Figure 2

Description

The present invention relates to a pneumatic tire.

The following Patent Document 1 describes pneumatic tires for all-terrain vehicles traveling on rough roads such as rocky areas and sandy areas. The tire comprises a belt laminated with the carcass inside the tread in the radial direction and a pair of reinforcing layers extending substantially inward in the radial direction from the end of the belt. The reinforcing layer contains a large number of reinforcing cords. It is stated that this reinforcing layer prevents the occurrence of cuts due to collision of crushed stone or the like.

Japanese Patent No. 6281976

In recent years, even in this type of tire, excellent fuel efficiency performance (low rolling resistance performance) is required.

The present invention has been devised in view of the above circumstances, and a main object of the present invention is to provide a pneumatic tire having excellent low rolling resistance performance while maintaining cut resistance.

The present invention is a pneumatic tire, the tread portion, the pair of sidewall portions, the pair of bead portions in which bead cores are embedded in each, the carcass straddling between the bead cores of the pair of bead portions, and the carcass. A reinforcing layer arranged outside the tire radial direction and on at least one of the pair of sidewall portions, the reinforcing layer comprises a cord strip in which a plurality of reinforcing cords are arranged in the tire circumferential direction. Includes discontinuous reinforcement layers spaced apart from each other.

It is desirable that the pneumatic tire according to the present invention has a tire circumferential length of 3 to 10 mm at the above intervals.

In the pneumatic tire according to the present invention, it is desirable that the carcass includes a carcass cord, and the reinforcing cord of each cord strip is arranged so as to intersect the carcass cord.

In the pneumatic tire according to the present invention, it is desirable that the carcass cord and the reinforcing cord intersect at an angle of 20 to 80 degrees.

In the pneumatic tire according to the present invention, it is desirable that the inner end of the reinforcing layer in the tire radial direction is located at less than 70% of the tire cross-sectional height from the bead baseline.

In the pneumatic tire according to the present invention, it is desirable that the outer end of the reinforcing layer in the tire radial direction is located at the tread portion.

In the pneumatic tire according to the present invention, the outer end of the reinforcing layer in the tire radial direction exceeds 10% of the tread width from the tire equatorial line to the outside in the tire axial direction, and the tread ends to the inside in the tire axial direction. It is desirable to be located in an area that exceeds 5% of the width.

In the pneumatic tire according to the present invention, it is desirable that the width of the cord strip is 10 to 30 mm.

In the pneumatic tire according to the present invention, it is desirable that the reinforcing cord is an organic fiber cord.

In the pneumatic tire according to the present invention, it is desirable that the reinforcing layer is arranged on each of the pair of sidewall portions.

By adopting the above configuration, the pneumatic tire of the present invention can exhibit excellent low rolling resistance performance while maintaining cut resistance.

It is sectional drawing of the right half of one Embodiment of the pneumatic tire of this invention. It is a partial perspective view of the pneumatic tire of FIG. It is a partial development view of the pneumatic tire of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of the right half of the tire meridian including the tire rotation axis (not shown) in the normal state of the pneumatic tire (hereinafter, may be simply referred to as “tire”) 1 of the present embodiment. FIG. 1 shows, for example, a tire 1 for a passenger car. However, the present invention may be applied to a tire 1 for heavy loads, light trucks, and the like.

The "normal state" is a no-load state in which the tire 1 is rim-assembled on a normal rim (not shown) and is filled with a normal internal pressure. In the present specification, unless otherwise specified, the dimensions and the like of each part of the tire 1 are values measured in this normal state.

The "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire 1 is based. For example, "standard rim" for JATMA and "Design Rim" for TRA. If it is ETRTO, it is "Measuring Rim". "Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which Tire 1 is based. For JATMA, "maximum air pressure", for TRA, the table "TIRELOAD LIMITSAT VARIOUS COLD". The maximum value described in "INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

As shown in FIG. 1, the tire 1 of the present embodiment includes a tread portion 2, a sidewall portion 3, and a bead portion 4. The tread portion 2 includes the tread surface 2a of the tire 1. The sidewall portions 3 are arranged on both sides of the tread portion 2 in the tire axial direction. The bead portion 4 is arranged inside each sidewall portion 3 in the tire radial direction. A bead core 5 is embedded in each bead portion 4.

In the present embodiment, the tire 1 includes a carcass 6 straddling between the pair of bead cores 5 and a reinforcing layer 8 arranged on the outer side of the carcass 6 in the tire radial direction and on at least one of the pair of sidewall portions 3. I'm out. In this embodiment, the reinforcing layer 8 is arranged on each of the pair of sidewall portions 3. Further, the tire 1 includes, for example, a belt layer 7 arranged outside the carcass 6 in the tire radial direction and inside the tread portion 2. The reinforcing layer 8 is arranged, for example, between the carcass 6 and the belt layer 7.

FIG. 2 is a partial perspective view of the tire 1 of FIG. FIG. 3 is a partially developed view of the tire 1 of FIG. As shown in FIGS. 1 to 3, the carcass 6 of the present embodiment is formed of two carcass plies 6A and 6B laminated inside and outside in the radial direction of the tire. The carcass 6 may be formed of one carcass ply or three or more carcass plies.

Each carcass ply 6A, 6B includes, for example, a carcass code 6c arranged at an angle θ1 of 75 to 90 ° with respect to the tire equator C. In the present embodiment, the carcass ply 6A and 6B each include a main body portion 6a extending between the bead cores 5 in a toroid shape, and a pair of folded-back portions 6b connected to the main body portion 6a and folded around the bead core 5. There is. The angle θ1 of the carcass code 6c is 90 ° in this embodiment.

For the carcass cord 6c, for example, an organic fiber cord such as nylon, polyester or rayon or a steel cord is preferably adopted. The diameter of the carcass cord 6c (not shown) is preferably 0.7 to 1.2 mm, for example.

The outer end 6e1 of the folded portion 6b of the inner carcass ply 6A in the tire radial direction is located outside the outer end 6e2 of the folded portion 6b of the outer carcass ply 6B in the tire radial direction. The outer end 6e1 of the inner carcass ply 6A is located, for example, 50% to 60% of the tire cross-sectional height H from the bead baseline BL. The "bead baseline BL" is a tire axial line passing through a rim diameter position determined by a standard based on the tire.

The belt layer 7 is formed of two belt plies 7A and 7B laminated inside and outside in the radial direction of the tire. Each of the belt plies 7A and 7B includes, for example, a belt cord 7c arranged at an angle θ2 of 10 to 35 ° with respect to the tire equator C, respectively. The belt cord 7c of the belt ply 7A is arranged so as to intersect the belt cord 7c of the belt ply 7B. For the belt cord 7c, for example, a steel cord is preferably adopted.

The inner belt ply 7A is formed wider than the outer belt ply 7B. The length W1 of the belt ply 7A in the tire axial direction is, for example, 68% to 95% of the tread width TW. The length W2 of the outer belt ply 7B in the tire axial direction is 80% to 105% of the length W1 of the inner belt ply 7A.

The "tread width TW" is a distance in the tire axial direction between the tread end Tes. The "tread end Te" is a ground contact position on the outermost side in the tire axial direction of the ground contact surface where a normal load is applied to the tire 1 in a normal state and the tire 1 is grounded on a flat surface at a camber angle of 0 °. "Regular load" is the load defined for each tire in the standard system including the standard on which the tire is based. For JATMA, "maximum load capacity", for TRA, "TIRE LOAD". The maximum value described in "LIMITS AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO.

In the present embodiment, the reinforcing layer 8 is arranged so as to be adjacent to the outer side of the outer carcass ply 6B in the tire radial direction. Such a reinforcing layer 8 suppresses damage to the carcass 6, for example, due to cut scratches caused by off-road driving.

The reinforcing layer 8 is formed to include a discontinuous reinforcing layer 8A in which cord strips 9 in which a plurality of reinforcing cords 9c are arranged are arranged at intervals p from each other in the tire circumferential direction. Such a reinforcing layer 8 suppresses an increase in tire mass. Therefore, the tire 1 of the present embodiment can exhibit excellent low rolling resistance performance while maintaining the cut resistance performance.

In the present embodiment, the cord strip 9 is formed in the form of a narrow tape in which each reinforcing cord 9c is topped with unvulcanized rubber 9d. Such a cord strip 9 is attached to the outer carcass ply 6B by a well-known method.

The reinforcing cord 9c is arranged parallel to the longitudinal direction of the cord strip 9, for example. The reinforcing cord 9c is not limited to such an embodiment, and may be arranged so as to be inclined with respect to the longitudinal direction of the cord strip 9.

The reinforcing cord 9c is an organic fiber cord in this embodiment. As the organic fiber, for example, polyester, nylon, rayon, aramid and the like are suitable.

The tire circumferential length w1 at intervals p of the cord strips 9 is preferably 3 to 10 mm. Since the length w1 of the interval p is 3 mm or more, the increase in the mass of the tire 1 is suppressed, and the low rolling resistance performance is highly exhibited. Since the length w1 of the interval p is 10 mm or less, cut scratches can be effectively suppressed and damage can be suppressed. In order to effectively exert such an action, the length w1 of the interval p is more preferably 5 mm or more, and further preferably 8 mm or less. The tire circumferential length w1 of the interval p is measured at the inner end 9i of the cord strip 9 in the tire radial direction.

In order to effectively exert the above-mentioned action, the width Wa of the cord strip 9 is preferably 10 mm or more, more preferably 15 mm or more, preferably 30 mm or less, and further preferably 25 mm or less. The width Wa of the cord strip 9 is the length in the tire circumferential direction.

The reinforcing cord 9c of the cord strip 9 is arranged so as to intersect the carcass cord 6c. As a result, the strength against impacts that cause cut scratches is increased, so that the cut resistance is further maintained. From this point of view, the angle α1 between the carcass cord 6c and the reinforcing cord 9c of the outer carcass ply 6B is preferably 20 degrees or more, more preferably 30 degrees or more, more preferably 40 degrees or more, and more preferably 80 degrees or less. Is desirable, 65 degrees or less is more desirable, and 50 degrees or less is even more desirable. The angle α1 is an angle on the inner end 9i of the cord strip 9 in the tire radial direction.

It is desirable that the complex elastic modulus E * 1 of the reinforcing code 9c is equal to or less than the complex elastic modulus E * 2 of the carcass code 6c. It is more desirable that the complex elastic modulus E * 1 of the reinforcing code 9c is smaller than the complex elastic modulus E * 2 of the carcass code 6c. As a result, the low rolling resistance performance can be enhanced, and the cut resistance performance can be largely maintained. In this specification, the complex elastic modulus is a value measured by a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. under the following conditions in accordance with the provisions of JIS-K6394.
Initial distortion: 10%
Amplitude: ± 1%
Frequency: 10Hz
Deformation mode: Tension measurement temperature: 70 ° C

As shown in FIG. 1, it is desirable that the inner end 8i of the reinforcing layer 8 in the tire radial direction is located at less than 70% of the tire cross-sectional height H from the bead baseline BL. As a result, damage due to cut scratches can be effectively suppressed. In order to effectively exert such an action, it is more desirable that the inner end 8i of the reinforcing layer 8 is 65% or less of the tire cross-sectional height H from the bead baseline BL. From the viewpoint of enhancing low rolling resistance performance, the inner end 8i of the reinforcing layer 8 is preferably 50% or more of the tire cross-sectional height H from the bead baseline BL, and more preferably 60% or more.

The inner end 8i of the reinforcing layer 8 of the present embodiment is located outside the folded portion 6b of the carcass 6 in the radial direction of the tire. This makes it possible to improve the low rolling resistance performance while maintaining the cut resistance performance. The inner end 8i of the reinforcing layer 8 is located, for example, outside the outer end 6e1 of the folded portion 6b of the inner carcass ply 6A in the radial direction of the tire. Although not particularly limited, the length L1 in the tire radial direction between the outer end 6e1 of the inner carcass ply 6A and the inner end 8i of the reinforcing layer 8 is preferably 5% or more of the tire cross-sectional height H. 10% or more is more desirable, 20% or less is more desirable, and 15% or less is even more desirable.

The outer end 8e of the reinforcing layer 8 in the tire radial direction is located at the tread portion 2. This makes it possible to suppress damage in the vicinity of the tread end Te, where cut scratches are likely to occur. In the present embodiment, the outer end 8e of the reinforcing layer 8 is the inner end 8f (shown in FIG. 3) of the reinforcing layer 8 in the tire axial direction.

The outer end 8e of the reinforcing layer 8 extends from the tire equatorial line C to the outside in the tire axial direction to exceed 10% of the tread width TW, and from the tread end Te to the inside in the tire axial direction to exceed 5% of the tread width TW. It is desirable to be arranged. By arranging the outer end 8e of the reinforcing layer 8 from the tire equator C to the outside in the tire axial direction at a position exceeding 10% of the tread width TW, the low rolling resistance performance is enhanced. By arranging the outer end 8e of the reinforcing layer 8 from the tread end Te to the inside in the tire axial direction at a position exceeding 5% of the tread width TW, high cut resistance is maintained. The distance L2 in the tire axial direction between the outer end 8e of the reinforcing layer 8 and the tread end Te is more preferably 10% or more, and further preferably 30% or less of the tread width TW.

In this embodiment, the reinforcing layer 8 overlaps with the belt layer 7 in the tire axial direction. In other words, the outer end 8e of the reinforcing layer 8 is located inside the outer end 7e of the belt layer 7 in the tire axial direction in the tire axial direction. The outer end 8e of the reinforcing layer 8 is sandwiched between the carcass 6 and the belt layer 7, for example. Such a reinforcing layer 8 increases the rigidity of the tread portion 2 and the sidewall portion 3. Considering that the low rolling resistance performance is enhanced, the distance L3 in the tire axial direction between the outer end 8e of the reinforcing layer 8 and the outer end 7e of the belt layer 7 (inner belt ply 7A) is 2 of the tread width TW. % Or more is desirable, 5% or more is more desirable, 10% or less is desirable, and 8% or less is even more desirable.

Although the particularly preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the illustrated embodiment and can be modified into various embodiments.

A pneumatic tire of size 265 / 60R18 having the basic structure of FIG. 1 for a passenger car was prototyped based on the specifications of Table 1. Then, tests were conducted on the cut resistance and low rolling resistance performance of each test tire. The common specifications and test methods for each test tire are as follows.
Rim used: 18 x 7.5J
Internal pressure: 240kPa (all wheels)
Outer end (H1 / H) of the folded part of the inner carcass ply: 55%
H1: Distance in the radial direction of the tire between the outer end of the folded part of the carcass ply inside and the bead baseline Inner end of the reinforcing layer (H2 / H): 30%
H2: Distance in the radial direction of the tire between the inner end of the reinforcing layer and the bead baseline The outer end of the reinforcing layer (L3 / TW): 15%
Carcass cord diameter: 0.65 mm
Cord strip width Wa: 20mm

<Cut resistance>
Each test tire was mounted on all wheels of a 2500cc passenger car. Then, after the test driver has traveled the above vehicle on a test course on an off-road road surface including rocks and rubble for about 500 km, it is comprehensively based on the depth of the cut scratches and the length of the cut scratches generated on the sidewall portion. Evaluated to. The result is displayed with a score of 100 for Comparative Example 1. The larger the value, the better the cut resistance.

<Low rolling resistance performance>
Rolling resistance was measured using a rolling resistance tester under the following conditions. The evaluation is displayed as an exponent with the value of Comparative Example 1 as 100. The smaller the value, the smaller the rolling resistance and the better.
Speed: 80km / h
Load: 80% of maximum load capacity (JATMA)

As shown in the table, the tires of the examples are excellent in low rolling resistance performance while maintaining cut resistance.

1 Pneumatic tire 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 8 Reinforcement layer 8A Discontinuous reinforcement layer 9 Cord strip 9c Reinforcement cord

Claims (10)

Pneumatic tires
With the tread part
A pair of sidewalls and
A pair of bead parts with bead cores embedded in each,
The carcass straddling between the bead cores of the pair of bead portions,
A reinforcing layer arranged outside the carcass in the radial direction of the tire and on at least one of the pair of sidewall portions.
The reinforcing layer includes a discontinuous reinforcing layer in which cord strips in which a plurality of reinforcing cords are arranged are arranged at intervals in the tire circumferential direction.
Pneumatic tires. The pneumatic tire according to claim 1, wherein the tire circumferential length of the interval is 3 to 10 mm. The carcass contains a carcass code and
The pneumatic tire according to claim 1 or 2, wherein the reinforcing cord of each cord strip is arranged so as to intersect the carcass cord. The pneumatic tire according to claim 3, wherein the carcass cord and the reinforcing cord intersect at an angle of 20 to 80 degrees. The pneumatic tire according to any one of claims 1 to 4, wherein the inner end of the reinforcing layer in the tire radial direction is located at less than 70% of the tire cross-sectional height from the bead baseline. The pneumatic tire according to any one of claims 1 to 5, wherein the outer end of the reinforcing layer in the tire radial direction is located in the tread portion. The outer end of the reinforcing layer in the tire radial direction is located in a region that exceeds 10% of the tread width from the tire equatorial line to the outside in the tire axial direction and exceeds 5% of the tread width from the tread end to the inside in the tire axial direction. The pneumatic tire according to claim 6. The pneumatic tire according to any one of claims 1 to 7, wherein the cord strip has a width of 10 to 30 mm. The pneumatic tire according to any one of claims 1 to 8, wherein the reinforcing cord is an organic fiber cord. The pneumatic tire according to any one of claims 1 to 9, wherein the reinforcing layer is arranged in each of the pair of sidewall portions.

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