JP2000016030A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the noise originating from vibrations of a tire and reduce the rolling resistance. SOLUTION: This pneumatic radial tire is structured so that a carcass layer 2 is mounted between a left and a right bead parts 1, 1 and a belt layer 4 is installed on the periphery of the carcass layer 2 in the tread part 3, wherein the side wall 6 between each bead part 1 and the tread part 3 is furnished with a plurality of dimples 7 laid in line band-shapedly in the tire circumferential direction in the region within 3/5h centering on the position corresponding to 1/2h, where (h) represents the height of the tire section, and the width H of the band region formed by the dimples 7 should meet 1/5h<=H while the ratio of the total area (s) of the dimples 7 to the area S of the band region should meet the condition 0.25<=s/S<=0.8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire with low noise and low fuel consumption, and more specifically, it is possible to reduce noise due to tire vibration and rolling resistance. A pneumatic radial tire.

[0002]

2. Description of the Related Art In recent years, deterioration of the environment of the earth has become a problem, and low noise and low fuel consumption have been particularly noticed as performances required for automobiles. In order to reduce the noise of this car, it is conceivable to cut off the noise from the exhaust muffler or engine room, and to reduce the fuel consumption, it is conceivable to improve the efficiency of the engine or use gasoline and electricity together. There have been many improvements.

In such a situation, the noise generated from the tires cannot be ignored as noise outside the vehicle, and the rolling resistance of the tires cannot be ignored as loss in the drive system. There is a demand for a further reduction in. 2. Description of the Related Art Conventionally, in a pneumatic radial tire, as a method of reducing noise, improvement of a tread pattern and improvement of rubber physical properties of a tread and a sidewall have been performed. Further, as a technique for reducing the rolling resistance, reduction of the hysteresis loss of the tread and enhancement of the rigidity of the belt layer have been performed. However, these methods have not always achieved sufficient reduction in tire noise and fuel consumption.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic radial tire capable of reducing noise due to tire vibration and reducing rolling resistance.

[0005]

In order to achieve the above object, a pneumatic radial tire according to the present invention has a carcass layer mounted between a pair of left and right bead portions, and a carcass layer is provided on a tread portion on an outer peripheral side of the carcass layer. In the pneumatic radial tire in which the belt layer is arranged, the side wall between the bead portion and the tread portion has a 3 / 5h area centered on a 1 / 2h position with respect to the tire sectional height h. A plurality of depressions arranged in a belt shape in the tire circumferential direction are provided, and the width H of the band-like region formed by the depressions is set to a relationship of ５h ≦ H,
And the total area s of the recessed portion with respect to the area S of the band-shaped region.
Are set in a relationship of 0.25 ≦ s / S ≦ 0.8.

As described above, a plurality of depressions arranged in a band in the circumferential direction of the tire are provided in a specific region of the sidewall, and the width H of the band formed by the depressions has a specific relationship with the height h of the tire section. In addition, by setting the ratio s / S of the total area s of the recessed portion to the area S of the band-shaped region to have a specific relationship, the rigidity of the sidewall is appropriately reduced and the transmission of the vibration received by the tread from the road surface is achieved. , Noise generated by the vibration of the sidewall can be suppressed.

Further, by providing the depressions in the sidewalls as described above, the strain generated in the tire is concentrated on the side region where the hysteresis loss is small, so that the distortion energy of the tread portion is reduced and the energy loss of the tire as a whole is reduced. And the rolling resistance can be reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 illustrates a pneumatic radial tire according to an embodiment of the present invention. In the figure, 1 is a bead portion, 2 is a carcass layer, 3
Denotes a tread portion, and 4 denotes a belt layer. A carcass layer 2 is mounted between a pair of right and left bead portions 1 and 1. The carcass layer 2 is disposed at a cord angle of substantially 90 ° with respect to the tire circumferential direction, and both end portions in the tire width direction are folded around the bead core 5 from the inside to the outside of the tire. On the outer peripheral side of the carcass layer 2 in the tread portion 3, a plurality of belt layers 4 are arranged over one circumference of the tire. The reinforcement cords of these belt layers 4 are inclined with respect to the tire circumferential direction, and the cords intersect each other between the layers.

In the pneumatic radial tire described above, the sidewall 6 between the bead portion 1 and the tread portion 3 has an area of 3 / 5h centered on a position 1 / 2h with respect to the tire sectional height h. Are provided with a plurality of depressions 7 discontinuous in the tire circumferential direction and arranged in a strip shape in the tire circumferential direction. The width H of the band-shaped region formed by these recesses 7 is in a relationship of 1 / 5h ≦ H, more preferably 3 / 10h ≦ H ≦ 3 / 5h, with respect to the tire cross-sectional height h. The ratio s / S of the total area s of the depressions 7 to the area S of the band-shaped region formed by the depressions 7 is 0.25 ≦ s / S ≦
0.8, more preferably 0.4 ≦ s / S ≦ 0.6.

As described above, in the specific region of the sidewall 6, a plurality of depressions 7 forming a band-shaped region having a specific width are provided discontinuously in the tire circumferential direction, and the rigidity of the sidewall 6 is reduced. As shown in (1), since the tread portion 3 attenuates the vibration received from the road surface, the sound generated by the vibration of the sidewall 6 can be suppressed. In addition, when a load is applied to the tire, the strain generated in the tire is concentrated on the sidewall 6 having a small hysteresis loss. Can be reduced.

In the present invention, even if the recess 7 is provided on the bead side or the tread side with respect to the region of 3/5 h centered on the position of 1/2 h with respect to the tire sectional height h, the vibration damping effect and the rolling resistance are provided. No reduction effect can be obtained. Also,
When the width H of the band-shaped region formed by the recessed portion 7 is less than 1 / 5h in the 3 / 5h region centered on the 1 / 2h position, a vibration damping effect and a rolling resistance reduction effect can be obtained. Can not.

Further, in order to effectively obtain the above-mentioned effect, the ratio s / S of the total area s of the depression 7 to the area S of the band-like region formed by the depression 7 is set to 0.25 ≦ s / S ≦ 0. It is necessary to make the relationship of 8. When the ratio s / S is less than 0.25, the vibration damping effect and the rolling resistance reduction effect become insufficient. On the other hand, when the ratio exceeds 0.8, the side stiffness is excessively reduced and steering stability is impaired. I will. For the same reason, the maximum width of the depression 7 in the tire radial direction is preferably 3 to 10 mm, and the depth of the depression 7 is preferably 1 to 3 mm.

The strip-shaped regions formed by the recesses 7 may be arranged at the same position on the left and right sidewalls 6 as shown in FIG. 2, or the tires may be disposed on the left and right sidewalls 6 as shown in FIG. They may be arranged at different positions in the radial direction. In particular, as shown in FIG. 3, when the band-shaped regions including the recessed portions 7 are arranged at different positions in the tire radial direction on the left and right sidewalls 6,
Since the phase of the left and right vibrations can be shifted, the sound transmitted to the inside of the vehicle can also be reduced.

The shape of the recess 7 is not particularly limited, and can be set to various shapes as needed. As the plan view shape of the concave portion 7, for example, FIG.
As shown in (a) to (h), a circle, an oval, an ellipse,
It can be square, rectangular, hexagonal, etc. As shown in FIGS. 5 (a) to 5 (o), for example, the cross-sectional shape of the concave portion 7 is rectangular, U-shaped, V-shaped, or a dovetail shape having a bottom wider than the opening. You may.

[0015]

[Example] The tire size is made common to 11R22.5,
As shown in FIG. 1, the tire according to the present invention in which a plurality of depressions are provided in a band-shaped region centered on a position １ ／ h with respect to the tire sectional height h of the sidewall, and the width H of the band-shaped region is １ ／ h A comparative tire 1 in which a plurality of recesses are provided in a band-shaped region having the same width as the above with the position 1 / 5h from the bead base as the innermost end, and a position 1 / 5h from the shoulder edge as the outermost end A comparative tire 2 in which a plurality of depressions were provided in a band-shaped region having the same width as that described above, and a conventional tire in which a depression was not provided in a sidewall were manufactured.

With respect to these test tires, noise and rolling resistance were measured by the following test methods, and the results are shown in Table 1. Noise: Speed 60 km / h according to JASO C606
The indoor noise at the time was measured. The evaluation results are shown as an index with the conventional tire being 100. The smaller the index value is, the lower the noise level is.

Rolling resistance: 1707 m in diameter with smooth surface
Each test tire was mounted on a wheel having a rim size of 22.5 × 7.50 using a drum testing machine equipped with a steel drum having a diameter of 700 mPa, an air pressure of 700 kPa, a load of 26.7 kg, and a speed of 80.
The vehicle was run under the condition of km / h, and the rolling resistance at that time was measured. The evaluation results are shown as an index with the conventional tire being 100. The smaller the index value is, the lower the rolling resistance is.

[0018]

[Table 1]

As is clear from Table 1, the tire of the present invention has reduced both noise and rolling resistance as compared with the conventional tire. On the other hand, although the comparative tires 1 and 2 have a plurality of dents formed in the side walls in a strip shape, the positions thereof are not appropriate, so that the effect of the tire of the present invention cannot be obtained.

[0020]

As described above, according to the present invention, a pneumatic radial tire in which a carcass layer is mounted between a pair of left and right bead portions and a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion. A plurality of depressions arranged in a band in the tire circumferential direction are provided in a specific region of the sidewall, and the width H of the band-shaped region formed by the depression is made to have a specific relationship with respect to the tire sectional height h. By setting the ratio s / S of the total area s of the depressions to the area S of the belt-shaped region in a specific relationship, it is possible to reduce noise due to tire vibration and reduce rolling resistance.

[Brief description of the drawings]

FIG. 1 is a perspective sectional view showing a pneumatic radial tire according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the pneumatic radial tire of FIG.

FIG. 3 is a sectional view showing a pneumatic radial tire according to another embodiment of the present invention.

FIGS. 4A to 4H are plan views illustrating the shape of a recess provided in a sidewall.

FIGS. 5A to 5O are cross-sectional views illustrating examples of the shape of a recess provided in a sidewall.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bead part 2 Carcass layer 3 Tread part 4 Belt layer 6 Side wall 7 Depression part

Claims (3)

[Claims] 1. A pneumatic radial tire in which a carcass layer is mounted between a pair of left and right bead portions and a belt layer is disposed on an outer peripheral side of the carcass layer in a tread portion, wherein a portion between the bead portion and the tread portion is provided. A plurality of depressions arranged in a strip shape in the tire circumferential direction are provided in a region of 3 / 5h centered on a position of 1 / 2h with respect to the tire cross-sectional height h on the side wall of the tire, and the depressions are formed. The width H of the band-shaped region is set to satisfy a relationship of ５h ≦ H, and the area S of the band-shaped region is
The ratio s / S of the total area s of the depressions to 0.25 is 0.25
A pneumatic radial tire having a relationship of ≦ s / S ≦ 0.8. 2. The tire radial maximum width of the recessed portion is 3 to 3.
The pneumatic radial tire according to claim 1, which has a thickness of 10 mm. 3. The pneumatic radial tire according to claim 1, wherein the depth of the recess is 1 to 3 mm.