JP2003127615A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fuel economy by reducing the air resistance of a tire. SOLUTION: A turbulent preventive range 11 having no recessed/projected portions 13 recessed and projected from a buttress surface 10S except for a groove 12 successively extending in a circumferential direction or a rib.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a buttress portion,
The present invention relates to a pneumatic tire in which air resistance is reduced by forming a turbulent flow prevention region having no irregularities other than a groove extending continuously in the circumferential direction.

[0002]

2. Description of the Related Art In recent years, in order to save resources and to protect the environment by reducing exhaust gas, there is a strong demand for the development of tires having excellent fuel economy. To that end, we have reduced the weight of tires, adopted low-heat-generating rubber with low energy loss for tread rubber, etc.
In addition, rolling resistance is reduced by increasing tire rigidity and the like, and some effects are achieved. However, with the stronger demand for environmental protection, further improvement of this fuel economy is desired.

Therefore, the present inventors have proposed to improve the fuel economy by reducing the air resistance of the tire itself and reducing the running resistance.

Here, the air resistance of the tire is mainly generated from a tread surface a and a buttress surface b which are visible when the tire is viewed from the front, as schematically shown in FIG. Among them, the width (tread width) of the tread surface a is dominant in the air resistance, and it is more advantageous to reduce the tread width in the air resistance, but on the other hand, the load capacity and the steering stability are improved. It is difficult to reduce the air resistance because it has a great influence on the tire performance such as a decrease in noise performance.

The buttress surface b is also a portion where air resistance is liable to be generated due to direct impact of the traveling wind, and in order to reduce the traveling resistance, it is necessary to reduce the turbulent flow that causes the resistance. Is.

Conventionally, as shown in FIG. 4, the buttress surface b is provided with information such as ridges c1 having a small pitch interval for improving the appearance, a trademark such as a symbol or a figure, and a tire size. Letter ring c2, lug groove c3 extending from the tread pattern, and groove c4 that is intermittent in the circumferential direction
And the like uneven portions were formed. Therefore, in order to suppress the occurrence of turbulent flow due to the uneven portion and reduce the air resistance, the turbulent flow prevention region having a smooth surface in the circumferential direction is formed on the buttress surface b by eliminating the uneven portion. Will be required.

That is, according to the present invention, the air resistance of the tire can be reduced on the basis of forming a turbulent flow prevention region in the buttress portion, which does not have a concavo-convex portion other than a groove or a rib extending continuously in the circumferential direction, It is intended to provide a pneumatic tire that can improve fuel economy.

[0008]

In order to achieve the above-mentioned object, the invention of claim 1 of the present application provides a tread portion having a tread groove on a tread surface, and a sidewall portion extending inward from the tread portion in a radial direction. And a bead portion located radially inward of the sidewall portion, and a groove or rib extending continuously in the circumferential direction in the buttress portion near the boundary between the tread portion and the sidewall portion. It is characterized in that a turbulent flow prevention region having no uneven portion which is uneven from the buttress surface is formed.

Further, in the invention of claim 2, the turbulent flow prevention region is a position that separates a distance 1.2 times the tire contact half width WT from the tire equator outward in the tire axial direction, and a tire cross section from the tire maximum diameter point. It is characterized in that it is arranged in a range area between the position and a position which is spaced radially inward by a distance 0.3 times the height H.

In the invention of claim 3, the turbulent flow prevention region has a region width W1 of 20 mm or more along the buttress surface in the tire axial direction.

According to the invention of claim 4, the turbulent flow prevention region extends from the tire split surface formed by the mating surfaces of the molds for molding the tread portion and the sidewall portion, in the tire axial direction and along the tire surface. It is characterized by including at least a region near the split surface between 5 mm inside the tread portion and 5 mm inside the sidewall portion.

In the invention of claim 5, the groove or rib extending continuously in the circumferential direction has a groove depth or rib height of 1.5.
It is characterized by being less than mm.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below.
This will be described together with the illustrated example. 1 is a meridional sectional view in the case where the pneumatic tire of the present invention is a passenger car tire, FIG.
[Fig. 3] is a perspective view showing a part thereof.

1 and 2, the pneumatic tire 1 is
Tread portion 2 in which tread groove G is provided on tread surface 2S
And sidewall portions 3 that extend inward from both ends thereof in the radial direction, and bead portions 4 that are located radially inward of each sidewall portion 3. A carcass 6 is bridged between the bead portions 4 and 4, and a belt layer 7 is arranged inside the tread portion 2 and outside the carcass 6.

The carcass 6 is composed of one or more carcass plies 6A in which carcass cords are arranged at an angle of, for example, 75 ° to 90 ° with respect to the tire circumferential direction. The carcass ply 6A has folded-back portions 6b that are folded back from the inner side to the outer side around the bead core 5 of the bead portion 4 and are locked to both ends of the main body portion 6a that straddles between the bead portions 4 and 4. A bead apex rubber 8 for reinforcing the bead portion is arranged between the main body portion 6a and the folded-back portion 6b, and extends in a tapered shape from the bead core 5 to the outside in the tire radial direction.

In the belt layer 7, the belt cords are arranged at an angle of, for example, 15 to 45 ° with respect to the tire circumferential direction.
One or more, in this example, two belt plies 7A and 7B are formed, and the cords intersect each other between the plies to reinforce the tread portion 2 with high rigidity. A band layer 9 composed of a band ply in which a band cord is spirally wound in the circumferential direction can be provided on the outer side of the belt layer 7 for the purpose of improving high-speed durability and steering stability, as in this example.

Next, the tread groove G arranged on the tread surface 2S includes a circumferential groove Gg extending continuously in the circumferential direction and a lug groove Gy extending in a direction intersecting with the circumferential groove Gg. Formed in a tread pattern.

In the present embodiment, the tread portion 2
Of the turbulent flow that continuously extends in the circumferential direction in the buttress portion 10, which is a portion near the boundary between the wall portion 3 and the sidewall portion 3.
1 is formed.

The turbulent flow prevention region 11 can include a groove 12 or a rib (not shown) extending continuously in the circumferential direction, but the continuous groove 12 and the uneven portion 13 other than the continuous rib.
Are eliminated, and as a result, a strip-shaped region having a smooth surface in the circumferential direction. In this example, the case where only the continuous groove 12 is provided is illustrated, but the continuous groove 12 and the continuous rib may not be provided, or both may be provided.

The uneven portion 13 is the buttress surface 1
The unevenness from 0S means, for example, as shown in FIG. 4, ridges c1 with a small pitch interval formed to enhance the appearance, lettering c2 for marking information such as a trademark and a tire size by a symbol or a figure, There are a lug groove c3 extending from the tread pattern, an interrupting groove c4 interrupting in the circumferential direction, and the like. By eliminating the uneven portion 13, the turbulent flow from the buttress portion 10 can be effectively suppressed, and the air resistance of the tire, that is, the running resistance can be reduced.

As the continuous groove 12 and the continuous rib which are allowed to be formed in the turbulent flow prevention region 11, the groove depth ha is shown in FIG.
The (rib height in the case of continuous ribs) is preferably 1.5 mm or less, and if it exceeds 1.5 mm, the running wind from the traveling direction is affected and turbulent flow tends to occur.
The continuous groove 12 and the continuous rib are generally used for decoration or when the tire is vulcanized and molded.
It is formed in order to blind the burrs generated on the tire dividing surface J formed by the mating surfaces of the molds for molding the side wall portion 3 and the side wall portion 3. Therefore, the groove width wa (rib width in the case of a continuous rib) and the cross-sectional shape of the continuous groove 12 are not particularly limited as long as they are constant in the circumferential direction. In this example, the radial inner edge 12E of the continuous groove 12 is positioned on the tire dividing surface J for the purpose of blindfolding the burrs.
Forming 2.

Here, as the turbulent flow prevention region 11,
As shown in FIG. 1, the tire ground contact half width W from the tire equator C
A position P1 that separates a distance L1 1.2 times T from the outside in the axial direction of the tire, and a maximum tire diameter CA (a point on the tread surface 2S where the tire diameter is maximum) from the tire cross-section height H of 0.
It is preferable to form the triple distance L2 in the range region Y between the position P2 and the position P2 that is radially inward.

This is because the range area Y of the buttress portion 10 is a portion on which the running wind is particularly strong,
By forming the turbulent flow prevention region 11 in this range region Y, the air resistance can be reduced more effectively. Further, when the turbulent flow prevention region 11 is provided on the inner side in the tire axial direction from the position P1, the turbulent flow prevention region 11 comes into contact with the ground during turning, which causes problems in drainage and steering stability.

At this time, it is preferable that the turbulent flow prevention region 11 has a region width W1 of 20 mm or more along the buttress surface in the tire axial direction. If it is less than 20 mm, the air resistance reducing effect tends to be insufficient. . From the viewpoint of reducing the air resistance, it is preferable to form the turbulent flow prevention region 11 in the entire range region Y, that is, to set the region width W1 to be equal to the width of the range region Y. Further, the turbulent flow prevention region 11 can be made wider to extend beyond the range region Y. However, in such a case, the formation effect of the ridge c1, the lettering c2, and the like is too small, in addition to the fact that no further reduction effect is expected, which is disadvantageous to the appearance performance.

Here, "tire contact half width WT" means a tire in a tread contact surface which can be grounded when a normal load is applied to a tire in a normal internal pressure state in which a rim is assembled on a normal rim and filled with a normal internal pressure. It means the tire axial distance from the equator C to the tread ground contact end.

The "regular rim" is a rim defined by the standard in the standard system including the standard on which the tire is based. For example, in the case of JATMA, the standard rim, T
RA means "Design Rim", and ETRTO means "Measuring Rim". Also, the "regular internal pressure"
Is the air pressure that the standard defines for each tire,
Maximum air pressure for JATMA, table for TRA "TI
RE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURE
If it is the maximum value described in "S" or ETRTO, "INFLATION P"
"Regular load" is the load that is specified for each tire in the standard, and is 0.7 times the maximum load capacity for JATMA and the table "TIRE LOA" for TRA.
0.7 times the maximum value stated in "D LIMITS AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAP if ETRTO
It is 0.7 times that of "ACITY".

The tire cross-section height H is the radial distance from the bead base line BL to the tire maximum radial point CA in the tire with the normal internal pressure.

The turbulent flow prevention area 11 is 5 m inward from the tire split surface J in the tire axial direction and along the tire surface for the purpose of reducing air resistance.
m, 5 mm inward of the sidewall, near the split surface Y
It is also preferable to include at least 1.

Although a particularly preferred embodiment of the present invention has been described above in detail, the present invention is not limited to the illustrated embodiment, and various modifications can be made and carried out.

[0030]

EXAMPLE Tire size 14 having the structure shown in FIGS.
A 5 / 80R14 tire was prototyped based on the specifications in Table 1, and the air resistance of each sample tire was measured and compared with each other.

(1) Air resistance: In an actual vehicle wind tunnel laboratory, an evaluation tire was mounted on a small front-wheel drive vehicle with a displacement of 1300 cc, and the aerodynamic force when the air was blown at a speed equivalent to 100 km / h was put under the wheel. It was measured using a floor-standing balance and evaluated by an index with the conventional example being 100. The smaller the number, the better.

[0032]

[Table 1]

In the first embodiment, by forming the turbulent flow prevention region,
It can be confirmed that the air resistance can be reduced by 0.6% as compared with the conventional example, which helps improve fuel economy. Further, as compared with Comparative Example 3 in which the tread pattern is further eliminated, Example 1 shows the same air resistance reducing effect, and thus it is understood that formation of the turbulent flow prevention region in the buttress portion is effective in reducing air resistance. .

[0034]

As described above, according to the present invention, the buttress portion is
Since the turbulent flow prevention region is formed without any irregularities other than the grooves and ribs that extend continuously in the circumferential direction, the air resistance of the tire can be reduced, which can contribute to the improvement of fuel economy.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a part thereof.

FIG. 3 is a sectional view showing a sectional shape of a continuous groove.

FIG. 4 is a perspective view of a tire for explaining a conventional technique.

[Explanation of symbols]

2 tread section 2S tread surface 3 Side wall part 4 bead section 10 Buttress Club 10S Buttress surface 11 Turbulence prevention area 12 grooves 13 uneven part Y range area J Tire split surface Area near Y1 split surface

Claims (5)

[Claims] 1. A tread portion having a tread groove on a tread surface, a sidewall portion extending radially inward from the tread portion, and a bead portion located radially inward of the sidewall portion. And, in the buttress portion near the boundary between the tread portion and the sidewall portion, a turbulent flow prevention region having no uneven portion which is uneven from the buttress surface other than the groove or the rib extending continuously in the circumferential direction is formed. A characteristic pneumatic tire. 2. The turbulent flow prevention region is located at a position that separates a distance 1.2 times the tire ground contact half width WT from the tire equator outward in the tire axial direction, and at a tire cross-section height H of 0. The pneumatic tire according to claim 1, wherein the pneumatic tire is arranged in a range area between a position that radially inwardly separates a triple distance. 3. The pneumatic tire according to claim 2, wherein the turbulent flow prevention region has a region width WT of 20 mm or more along the buttress surface in the tire axial direction. 4. The turbulent flow prevention region is 5 mm inside the tread portion from the tire dividing surface formed by the mating surfaces of the molds for molding the tread portion and the sidewall portion, along the tire axial direction and along the tire surface. 2. A region near the split surface of at least 5 mm is included inwardly of the sidewall portion.
The pneumatic tire according to any one of to 3. 5. The pneumatic tire according to claim 1, wherein the groove or rib extending in the circumferential direction has a groove depth or rib height of 1.5 mm or less.