JP3292410B2 - Pneumatic tire - Google Patents

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 reducing rolling resistance and reducing fuel consumption.

[0002]

2. Description of the Related Art In recent years, there has been a demand for reducing the rolling resistance of tires and reducing fuel consumption in order to improve the environment.

[0003] On the other hand, it is known that in a pneumatic tire, the rolling resistance during running is reduced by increasing the tire internal pressure to reduce the contact area and reduce the amount of deformation of the tread portion during contact.

Conventionally, as shown in FIG. 3, a tire used at such a high internal pressure has a tread surface a passing through a tire equatorial plane point and approximately 0.5 to 0.6 times a tire sectional height h. It is formed by a single arc having a radius of curvature R1 larger than the radius of curvature R2 of the carcass. Also its tread width d
Was formed in a width 0.9 to 1.3 times the tire width w.

[0005]

However, as described above, when the tread portion is formed to be wide and the tread surface is formed by an arc having a single radius R1, the distribution of the contact pressure on the tread surface a greatly varies. Therefore, there is a problem that the rolling resistance increases due to the occurrence of slip in the ground contact area during traveling. Also, the amount of tread rubber increases and the tire weight increases.

[0006] The inventors of the present invention have made the tread width in the axial cross section of the tire smaller than that of the conventional tire, and at the same time, in order to suppress the movement to the tread portion, the rolling resistance improving rubber layer in which the orientation of short fibers is regulated inside the tread. It has been found that the rolling resistance can be reduced by arranging them, thereby completing the present invention.

[0007] Normally, in a high internal pressure tire, the tire internal strain due to the internal pressure is made as uniform as possible by making the axial cross-sectional shape of the tire close to a perfect circle, that is, making the flatness close to 1. It has also been found that by efficiently utilizing the strength of the carcass, the dimensions of the carcass can be reduced and the tire weight can be reduced.

An object of the present invention is to provide a pneumatic tire that can reduce fuel consumption by reducing rolling resistance and reducing the weight of the tire.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a bias-type pneumatic tire having a carcass that is folded from a tread portion through a sidewall portion and around a bead core of a bead portion. In a state where the air pressure and the standard load are applied, the tread width, which is the length between the outer peripheral points in the tire axial direction of the tread surface to contact the ground, is set to 0.30 times or more and 0.6 times or less of the tire sectional width, and the tread is used. Inside the part and adjacent to the outside of the carcass in the radial direction, the iodine adsorption amount is 35 parts per 100 parts by weight of the rubber component.
~ 120 mgr / gr carbon black for 30-60
And parts, with the short fibers disposed a rolling resistance improvement rubber layer made of a rubber composition comprising 20-50 parts by weight, the
The rolling resistance improving rubber layer has a thickness (t) of 0.5 to 2.0 m.
m, width (WR) is 1.0 to 2.0 of tread width (WT)
Times, and the short fibers are oriented at 0 to 30 ° with respect to the circumferential direction.
Re yet that flat rate is 0.95 to 1.05 or less
Features.

[0010]

[Function] A rolling resistance improving rubber layer reinforced with short fibers over the width of the tread is arranged inside the tread and outside in the carcass radial direction, so the movement of the tread rubber is suppressed and the rolling resistance is reduced. Can. Further, the distribution of tire strain caused by applying the internal pressure can be made uniform, and thus the internal pressure can be set high, so that the contact area of the tread portion is small and stable, so that the rolling resistance can be reduced.

Since the rolling resistance improving rubber layer is arranged inside the tread rubber layer, the movement of the tread is suppressed,
The rolling resistance can be further reduced.

Further, the tread width of the tread surface is set to 0.3 to 0.6 times or less of the tire cross-sectional width, and by reducing the tread width, it becomes easy to make the cross-sectional shape close to a circle,
In addition, the contact width in the tire axial direction can be reduced.

Further, when the radius of curvature R1 of the tread surface (when mounted on the standard rim and filled with the specified maximum air pressure) is set to 1.05 to 1.30 times the radius of curvature R2 of the crown portion of the carcass, another configuration is adopted. Accordingly, the cross-sectional thickness of the shoulder portion can be reduced, the tire weight can be reduced, and the ground contact surface S can be formed in a rectangular shape that does not spread in the tire axial direction as shown in FIG. Therefore, the deviation of the peripheral speed between the tire equator C and the vicinity of the tread edge E is small, and the rolling of the tire shown in FIG. 3 is smaller than that of the tire having a diamond-shaped tread having a long shape in the tire axial direction shown in FIG. Resistance can be reduced.

As described above, according to the present invention, since the above-described structure is organically combined, the rolling resistance can be reduced and the tire weight can be reduced, which can contribute to energy saving of the vehicle.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, the pneumatic tire 1 has a flatness of 0.95 or more and 1.05 or less, which is a ratio of a tire cross-sectional width WB, which is a maximum width in the axial direction of the tire, to a cross-sectional height H in the tire radial direction. , A perfect circle or a sectional shape substantially close to a perfect circle. Thereby, the internal strain of the tire due to the internal pressure is made uniform, and the utilization efficiency of the strength of the carcass is increased.

The pneumatic tire 1 has sidewall portions 3 extending radially inward from both ends of a tread portion 2 and bead portions 4 provided at radial inner ends of the sidewall portions 3. And a carcass 6 that is folded from the tread portion 2 through the sidewall portion 3 and around the bead core 5 of the bead portion 4,
A rolling resistance improving rubber layer 7 is provided inside the tread portion 2 and radially outside the carcass 6.

In this embodiment, the carcass 6 is composed of two carcass plies wound around the bead core 5 from the inside to the outside in the tire axial direction, and the carcass plies are made of organic fibers such as nylon, polyester and aromatic polyamide. Carcass cord 35 to 4 for tire equator
Form a bias arrangement inclined at 5 °. The cords of the two carcass plies are arranged in a direction crossing each other.

In the pneumatic tire 1, when a specified load is applied in a standard state in which a rim is assembled on a standard rim and a specified maximum air pressure is applied, the tread portion 9 is in contact with a flat road surface and the outer edge of the tread surface 9 in the tire axial direction. The tread width WT, which is the length between E and E, is set to 0.40 times or more and 0.6 times or less of the tire sectional width WB. When the tread width WT is less than 0.4 times the tire cross-sectional width WB, the area of the contact surface S shown in FIG. 2 becomes small, resulting in a large contact pressure and poor wear resistance.
Further, durability is reduced due to abrasion wear at the edge E. Conversely, if it exceeds 0.60 times, it approaches the conventional tire,
As shown in FIG. 4, the contact surface s extends in the tire axial direction, and a slip occurs on the contact surface s due to a difference in radius on the tread surface, and the rolling resistance increases.

The tire 1 has a first circular arc K1 forming a tread surface 9 on a radially outer side of the tire maximum width position M.
A second arc K2 formed of an arc having a radius of curvature R3 to form the buttress surface 10; and a third arc formed of an arc having a radius of curvature R4 and smoothly connected to the second arc K2 and extending to the outer edge point E. K3. The first arc K1 forming the tread surface 9 has a radius of curvature R2 at the tread portion 2 passing through a point on the tire equator C and passing through a middle position of the carcass 6 in a tire meridian section.
It has an arc curved surface with a curvature radius R1 that is 1.05 to 1.30 times the radius of curvature.

Thus, the radius of curvature R of the first arc K1
By setting 1 to be 1.05 to 1.30 times the radius of curvature R2 of the carcass 6, the amount of rubber forming the buttress surface 10 can be reduced, and the spread of the ground contact surface S shown in FIG. 2 is stabilized. When the radius of curvature R1 is less than 1.0 times the radius of curvature R2, when the tire lands, the surface that comes into contact with the tire easily reaches the buttress portion, and the contact width in the tire axial direction increases. When the difference between the circumferential lengths at the edge and the edge is large, slippage occurs during running and the rolling resistance increases. The preferred range is 1.10 to 1.30.
It is twice.

The rubber hardness of the rubber layer on the surface forming the tread surface 9 and the buttress surface 10 of the tread portion 2 is JIS.
It is preferable to set the A hardness in the range of 55 to 70 °.

Furthermore, the second arc K2 of the buttress surface 10
Is preferably a radius of an arc having substantially the same center as the curvature radius R2 of the carcass and passing near the tire equator point.

The rolling resistance improving rubber layer 7 has an iodine adsorption amount of 35 to 120 m with respect to 100 parts by weight of the rubber component.
30 to 60 parts by weight of gr / gr carbon black,
It is made of a rubber composition containing 20 to 50 parts by weight of short fibers, and the rolling resistance improving rubber layer can suppress the movement of the tread rubber and lower the rolling resistance.

The reason for using carbon black having an iodine adsorption amount of 35 to 120 mgr / gr with respect to 100 parts by weight of the rubber component is to balance the tire strength and the rolling resistance, although it depends on the filling amount. When it is less than / gr, the strength as a tread rubber is inferior, the deformation amount increases, and the rolling resistance increases. 120mgr /
When it exceeds gr, the internal energy loss of the tread rubber increases and the rolling resistance increases.

The short fibers are nylon, polyester,
It is obtained by cutting an organic fiber cord such as aramid into a length of about 3 to 15 mm. As the organic fiber cord, a cracked cord of a waste tire can be suitably used.

Further, the rolling resistance improving rubber layer 7 has a width (WR) of 1.0 to 2.0 times the tread width (WT) and is wider than the tread width to suppress the movement of the tread rubber. For the same purpose, the short fibers are preferably oriented at 0 to 30 ° with respect to the circumferential direction. In order not to excessively increase the rigidity of the tread portion, the thickness (t) is set to 0.5 to 2.0.
mm.

[0027]

[Specific example] The tire size is 2.25-144P. R.
With the configuration shown in FIG. 1, tires of Examples and Comparative Examples were made as prototypes according to the specifications shown in Table 1, and their performances were tested. Note that a tire having a conventional configuration shown in FIG. 3 (Comparative Example N
o. A test was also performed for 11), and the performance was compared.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

[Table 3]

In the measurement of the rolling resistance, the rolling resistance coefficient at a load of 85 kgf and an internal pressure of 6.0 ksc and a speed of 80 kpH was calculated by an indoor drum tester.
o. The value of 11 was expressed as an index with 100 as the value. The smaller the value, the better.

As a result of the test, it was confirmed that the rolling resistance of the example was lower than that of the comparative example.

[0033]

As described above, the pneumatic tire of the present invention has the following features.
The rolling resistance can be reduced, and the weight of the tire can be reduced, which contributes to a reduction in the fuel consumption of the vehicle. For example, it can be used for a solar car and the like.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view showing the ground plane.

FIG. 3 is a sectional view showing a conventional tire.

FIG. 4 is a plan view showing the ground plane.

[Explanation of symbols]

 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 9 Tread surface 10 Buttress surface C Tire equator E Outer edge WB Tire section width (at the time of inflation) WT Tread width

Continuation of the front page (56) References JP-A-58-30806 (JP, A) JP-A-55-79704 (JP, A) JP-A-63-263104 (JP, A) , U) JP-B 64-5060 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60C 11/00-11/24 B60C 1/00 B60C 9/00-9/30

Claims (2)

(57) [Claims] 1. A bar having a carcass which is turned from a tread portion through a sidewall portion and around a bead core of a bead portion.
In a pneumatic tire of the ias type, in a state where a rim is assembled and a specified maximum air pressure and a standard load are applied, a tread width which is a length between outer edge points in a tire axial direction of a tread surface to be contacted with a tire is defined as a tire sectional width of 0. .30 times or more and 0.6
30 times by weight of carbon black having an iodine adsorption amount of 35 to 120 mgr / gr with respect to 100 parts by weight of the rubber component, adjacent to the inside of the tread portion and radially outside of the carcass. 20 to 5 fibers
And a rolling resistance improving rubber layer comprising a rubber composition containing 0 parts by weight, and the rolling resistance improving rubber layer has a thickness (t) of 0.5 to 2.0.
0 mm, width (WR) is 1.0 to 2. of tread width (WT).
0 times, and the short fibers are oriented at 0 to 30 ° to the circumferential direction
It is a pneumatic tire, characterized in that moreover an aspect ratio is 0.95 to 1.05 or less. 2. The curvature radius R1 of the tread surface at the tread width is 1.05 to 1.30 of the curvature radius R2 of the carcass.
The pneumatic tire according to claim 1, wherein the pneumatic tire is doubled.