JP2003146012A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire that can improve fuel economy by reducing rolling resistance and maximally preventing reduction in wear resistance and uneven wear resistance in the pneumatic tire. SOLUTION: With the tire 10 mounted on a standard rim and brought to a low internal pressure of 100 kPa, H/S is set low at 0.750 to 0.770, where H is a distance measured in a tire diameter direction from an inner end of a bead core 12 about the tire diameter direction to an outer end of a carcass 14 about the tire diameter direction and S is a maximum width of the carcass 14 about a tire axis direction, and h0/H is set at 0.570 to 0.590, where h0 is a distance measured in the tire diameter direction from the inner end of the bead core 12 about the tire diameter direction to a maximum width point of the carcass 14 about the tire axis direction, so that rolling resistance can be reduced. H1/h0 is set at 0.910 to 0.930, where h1 corresponds to h0 when the tire 10 is inflated to a standard internal pressure, so that uneven wear resistance can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a heavy duty pneumatic tire for trucks and buses.

[0002]

2. Description of the Related Art Trucks and buses running on ordinary roads are
Pneumatic tires for heavy loads are used. In such a heavy-duty pneumatic tire, the problem of reducing the rolling resistance of the tire has been solved by reducing the internal loss (strain energy loss) of the tread rubber.

On the other hand, however, there has been a problem that the wear resistance and uneven wear resistance are deteriorated.

[0004]

In view of the above facts, the present invention reduces the rolling resistance and wear resistance of the pneumatic tire by combining the sectional shape of the pneumatic tire with the physical properties of the tread rubber. -It is an object of the present invention to provide a pneumatic tire that can prevent deterioration of uneven wear resistance as much as possible and that can improve fuel consumption.

[0005]

A pneumatic tire according to claim 1, wherein a pair of left and right bead cores, a carcass straddling the bead cores in a toroidal shape, and a belt arranged radially outside the carcass. A tread rubber formed on the outer side in the tire radial direction of the belt, wherein the pneumatic tire is mounted on a standard rim and is filled with a low internal pressure of about 100 kPa. The distance measured from the inner end in the tire radial direction to the outer end in the tire radial direction of the carcass is H, the maximum axial width of the carcass in the tire axial direction is S, and the inner radial direction of the bead core in the tire radial direction. When the distance measured along the tire radial direction from the end portion to the tire axial maximum width of the carcass is h0, H
/ S is 0.750 or more and 0.770 or less, and h0 /
H is 0.570 or more and 0.590 or less, and the tire diameter from the tire radial inner end of the bead core to the tire axial maximum width of the carcass when the pneumatic tire is filled with standard internal pressure. When the distance measured along the direction is h1, h1 / h0 is 0.910 or more and 0.930 or less.

Next, the function and effect of the pneumatic tire according to claim 1 will be described.

As a result of an experiment conducted by the inventor, the distance measured along the tire radial direction from the tire radial inner side end of the bead core to the carcass tire radial outer end is defined as H, and the carcass tire axial maximum is measured. When S is set to be large, H
It has been found that by lowering / S, the strain energy loss, which is the main cause of rolling resistance generation, is reduced.

Therefore, in the present invention, H / S is 0.75.
When the distance measured along the tire radial direction from the tire radial inner side end of the bead core to the tire axial maximum width of the carcass is set to 0 or more and 0.770 or less, h0 / H is 0.570 or more and 0.59
By setting it to 0 or less, strain energy loss can be reduced, and rolling resistance can be reduced.

On the other hand, as a result of an experiment conducted by the inventor, the distance measured along the tire radial direction from the tire radial inner end of the bead core to the tire axial maximum width of the carcass was set to h0, and a pneumatic tire was obtained. When the distance measured along the tire radial direction from the tire radial inside end of the bead core when filled with the standard internal pressure to the tire axial maximum width of the carcass is h1, then h1 / h0 is 0.910 or more and 0. It has been found that when it is set to 930 or less, it is optimal for uneven wear resistance and the uneven wear resistance is improved.

Therefore, in the present invention, h1 / h0 is 0.9
By setting it to 10 or more and 0.930 or less, the uneven wear resistance can be improved.

The abrasion resistance can be improved by increasing the tension of the belt.

In the present specification, the "inner end portion of the bead core in the tire radial direction" refers to the innermost end portion of the bead core in the tire radial direction that is located at the innermost side in the tire radial direction.

"The tire radial outer side end of the carcass" means the center point of the tire radial outer thickness of the carcass in the tire radial direction.

"The maximum width of the carcass in the axial direction of the tire"
Means the distance between the center points of the tire axial thickness of the maximum width portion of the carcass in the axial direction of the tire.

The "standard rim" means a rim defined by a standard issued by JATMA (Japan), TRA (US), ETRTO (Europe) and the like.

The "standard internal pressure" means the air pressure with respect to the maximum load in the applicable size and ply rating specified in the standard.

In the pneumatic tire according to claim 2, the viscoelasticity of the tread rubber has a dynamic storage elastic modulus E ′ of 5.3 MPa or more at room temperature of 25 ° C. and 2% strain.
It is 3 MPa or less, and the loss tangent tan δ has a physical property value of 0.09 or more and 0.19 or less.

Next, the function and effect of the pneumatic tire of claim 2 will be described.

The viscoelasticity of the tread rubber has room temperature of 25 ° C. and 2
Under the condition of% strain, the dynamic storage elastic modulus E'is 5.3MP.
Since the loss tangent tan δ is a or more and 9.3 MPa or less and the physical property value is 0.09 or more and 0.19 or less, the strain energy loss can be reduced.

As a result, the rolling resistance of the tire can be more effectively reduced while maintaining the wear resistance and the uneven wear resistance of the tire.

The "dynamic storage elastic modulus" is the real part of the complex elastic modulus, and means the magnitude of stress components of the same phase when a unit sinusoidal strain is applied.

Here, the "complex elastic modulus" means the ratio of the maximum stress to the maximum strain in dynamic viscoelasticity, which is calculated as a complex number as a vector. "Dynamic viscoelasticity" refers to the behavior of the combination of viscosity and elasticity when a constant sinusoidal strain is applied to a material. This is obtained by measuring stress with respect to strain or strain with respect to stress.

On the other hand, the "loss tangent" means the tangent of the loss angle δ. "Loss angle" means the phase angle between strain and stress.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION A pneumatic tire according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the pneumatic tire 10
Includes a pair of bead cores 12. The bead core 12 has a hexagonal cross section.

A carcass 14 extends in a toroidal shape between the left and right bead cores 12.

A belt 16 is arranged outside the carcass 14 in the radial direction of the tire.

A tread rubber 18 is arranged outside the belt 16 in the tire radial direction.

The viscoelasticity of the tread rubber 18 is 2 at room temperature.
Under the conditions of 5 ° C. and 2% strain, the dynamic storage elastic modulus E ′ is 5.3 MPa or more and 9.3 MPa or less, and the loss tangent t
It has a physical property value such that an δ is 0.09 or more and 0.19 or less.

Here, the cross-sectional shape of the pneumatic tire 10 which is an essential part of the present invention will be described.

As shown in FIG. 2, with the pneumatic tire 10 mounted on a standard rim and filled with a low internal pressure of about 100 kPa, the inner end of the bead core 12 in the tire radial direction to the outer end of the carcass 14 in the tire radial direction. Is H, a tire axial maximum width of the carcass 14 is S, and a tire diameter from the tire radial inner end of the bead core 12 to the tire axial maximum width of the carcass 12 is S. When the distance measured along the direction is h0, H / S is set to 0.750 or more and 0.770 or less, and h0 / H is set to 0.570 or more and 0.590 or less. .

The distance measured along the tire radial direction from the tire radial inside end of the bead core 12 when the pneumatic tire 10 is filled with the standard internal pressure to the tire axial maximum width of the carcass 14 is h1. If h1 / h0
Is set to 0.910 or more and 0.930 or less.

Next, the pneumatic tire 1 according to this embodiment
The action and effect of 0 will be described.

As shown in FIG. 3, in the experiment conducted by the inventor, the relationship between the rolling resistance and H / S is as shown by the curve A. From this relationship, by decreasing the H / S, the tension of the belt 16 is increased, the deformation of the tread portion is reduced, and by using the tread rubber 18 having a low internal loss of the above-mentioned physical property values and high elasticity, It has been found that the strain energy loss of the pneumatic tire 10 which is the main factor of rolling resistance generation can be reduced.

Therefore, H / S is 0.750 or more and 0.77.
0 or less (area B in FIG. 3) is set relatively low, and h
By setting 0 / H to 0.570 or more and 0.590 or less, strain energy loss can be reduced and rolling resistance can be reduced.

On the other hand, as a result of an experiment conducted by the inventor, h1 /
It has been found that when h0 is set to 0.910 or more and 0.930 or less, it becomes optimum for uneven wear resistance and the uneven wear resistance is improved.

Therefore, in the pneumatic tire 10 of the present invention, the uneven wear resistance can be improved by setting h1 / h0 to 0.910 or more and 0.930 or less. As described above, the uneven wear resistance can be improved by controlling the rate of change of the footprint due to running growth by h1 / h0.

Even when the tread rubber 18 having a low internal loss (small strain energy loss) is used, the belt 1
By increasing the tension (strength) of 6, wear resistance can be improved.

As described above, the pneumatic tire 1 of the present invention
When it is 0, the rolling resistance can be reduced, the wear resistance and the uneven wear resistance can be prevented from being deteriorated as much as possible, and the fuel consumption can be improved. (Test Example) Next, using the pneumatic tire of the present invention, a test for rolling resistance, wear resistance and uneven wear resistance was conducted.

For the test, tire size TBR12R22.
Using a tire of 5 16PR, three types of tires, a conventional tire, the present invention tire and the present invention tire, were tested.

Here, the conventional tire conditions are H / S set to 0.790, h1 / h0 set to 0.900, dynamic storage modulus E ′ set to 7.3 MPa, and loss. The tangent tan δ was set to 0.17.

The condition of the tire of the present invention is that H / S is 0.7.
60, h1 / h0 is set to 0.920, dynamic storage elastic modulus E ′ is set to 7.3 MPa, and loss tangent ta is set.
nδ was set to be 0.17.

The condition of the tire of the present invention is that H / S is 0.7.
60, h1 / h0 is set to 0.920, dynamic storage elastic modulus E ′ is set to 7.3 MPa, and loss tangent ta is set.
nδ was set to be 0.14.

The results of this test are shown in Table 1 below.

In the evaluation of this test, the evaluation of the conventional tire was used as a standard (100), and the evaluation for the evaluation of the conventional tire was shown as an index. The smaller the numerical value in Table 1, the better.

[0046]

[Table 1] As shown in Table 1 above, it was found that the tire of the present invention and the tire of the present invention had improved rolling resistance as compared with the conventional tire.

In terms of wear resistance and uneven wear resistance,
In the tire of the present invention and the tire of the present invention, although it is numerically slightly reduced as compared with that of the conventional tire, if there is a decrease of this extent, there is no particular problem in the functions of wear resistance and uneven wear resistance, It can be said that the wear resistance and the uneven wear resistance are maintained.

[0048]

According to the pneumatic tire of the present invention, rolling resistance can be reduced, wear resistance and uneven wear resistance can be prevented from being lowered as much as possible, and fuel consumption can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a pneumatic tire according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a pneumatic tire according to an embodiment of the present invention.

FIG. 3 is a graph showing the relationship between rolling resistance and H / S and the relationship between uneven wear and h1 / h0 of a general pneumatic tire.

[Explanation of symbols]

10 pneumatic tires 12 bead core 14 carcass 16 belts 18 tread rubber

Claims (2)

[Claims] 1. A pair of left and right bead cores, a carcass straddling the bead cores in a toroidal shape, a belt arranged outside the carcass in the tire radial direction, and a tread rubber formed outside the belt in the tire radial direction. And a pneumatic tire having a pneumatic tire of about 100 kP attached to a standard rim.
In a state in which the low internal pressure of a is filled, the distance measured along the tire radial direction from the tire radial inside end of the bead core to the tire radial outside end of the carcass is H, and the tire axial direction of the carcass When the maximum width is S and the distance measured along the tire radial direction from the tire radial inside end of the bead core to the tire axial maximum width of the carcass is h0, H / S is 0.750 or more. 0.770 or less, h0 / H is 0.570 or more and 0.590 or less, and when the pneumatic tire is filled with a standard internal pressure, a tire radial direction inner end portion of the bead core of the carcass When the distance measured along the tire radial direction up to the maximum tire axial width is h1, h1 / h0 is 0.910 or more and 0.930 or less. Pneumatic tire. 2. The viscoelasticity of the tread rubber has a room temperature of 25.
Under the condition of 2 ° C. strain and 2 ° C., the dynamic storage elastic modulus E ′ is 5.3 MPa or more and 9.3 MPa or less, and the loss tangent tan δ is 0.09 or more and 0.19 or less. The pneumatic tire according to claim 1.