JP4295455B2 - Pneumatic tire - Google Patents

Description

【００３３】
参考例は、乱流防止領域の形成により、従来例に比して空気抵抗を０．６％低減でき、低燃費性の向上に役立つのが確認できる。又トレッドパターンをさらになくした比較例３と比べ、同等の空気抵抗低減効果がみられることから、バットレス部における乱流防止領域の形成が、空気抵抗低減に有効であることがわかる。
【００３４】
【発明の効果】
叙上の如く本発明は、バットレス部に、周方向に連続してのびる溝やリブ以外の凹凸部を有しない乱流防止領域を形成しているため、タイヤの空気抵抗を低減でき、低燃費性の改善に貢献することができる。
【図面の簡単な説明】
【図１】本発明の一実施例のタイヤの断面図である。
【図２】その一部を示す斜視図である。
【図３】連続溝の断面形状を示す断面図である。
【図４】従来技術を説明するタイヤの斜視図である。
【符号の説明】
２ トレッド部
２Ｓ トレッド面
３ サイドウォール部
４ ビード部
１０ バットレス部
１０Ｓ バットレス表面
１１ 乱流防止領域
１２ 溝
１３ 凹凸部
Ｙ 範囲領域
Ｊ タイヤ割面
Ｙ１ 割面近傍領域[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire in which air resistance is reduced by forming a turbulent flow prevention region in a buttress portion that does not have an uneven portion other than a groove extending continuously in a circumferential direction.
[0002]
[Background Art and Problems to be Solved by the Invention]
In recent years, there has been a strong demand for the development of tires with excellent fuel efficiency in order to save resources and protect the environment by reducing exhaust gas. Therefore, rolling resistance is reduced by reducing the weight of the tire, adopting low heat-generating rubber with low energy loss for tread rubber, etc., and increasing tire rigidity, etc., and a certain degree of effect is achieved. . However, with the strong demand for environmental protection, further improvement of this fuel efficiency is desired.
[0003]
In view of this, the present inventors have proposed to improve fuel efficiency by reducing the air resistance of the tire itself and reducing the running resistance.
[0004]
Here, the air resistance of the tire is mainly generated from the tread surface a and the buttress surface b that are visible when the tire is viewed from the front, as schematically shown in FIG. Among these, the width (tread width) of the tread surface a is dominant in the air resistance, and it is advantageous for the air resistance to narrow the tread width, but on the other hand, the load capacity and the steering stability are reduced. It is difficult to reduce the air resistance because it has a great influence on the tire performance, such as causing a decrease in noise performance.
[0005]
The buttress surface b is also a part where air resistance is likely to be generated because the traveling wind directly hits it. In order to reduce the traveling resistance, it is necessary to reduce the turbulent flow that causes the resistance.
[0006]
Conventionally, as shown schematically in FIG. 4, the buttress surface b has a ridge c1 with a small pitch interval for improving the appearance, and a lettering c2 for marking information such as a trademark and tire size such as symbols and figures. Irregularities such as a lug groove c3 extending from the tread pattern and a groove c4 intermittent in the circumferential direction are formed. Therefore, in order to suppress the occurrence of turbulent flow due to the uneven portion and reduce the air resistance, a turbulent flow prevention region that forms a smooth surface in the circumferential direction is formed on the buttress surface b by eliminating the uneven portion. It is necessary to do.
[0007]
In other words, the present invention can reduce the air resistance of the tire based on the formation of a turbulent flow prevention region having no irregularities other than grooves or ribs extending continuously in the circumferential direction in the buttress portion, and can reduce fuel consumption. It aims to provide a pneumatic tire that can improve the above.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 of the present application includes a tread portion provided with a tread groove on a tread surface, a sidewall portion extending radially inward from the tread portion, and a radial direction of the sidewall portion. A bead portion located inward,
And, in the buttress portion near the boundary between the tread portion and the sidewall portion, a turbulent flow prevention region that is continuous without having a step with the tread surface is formed,
The turbulent flow prevention region has continuous grooves or continuous ribs extending continuously in the circumferential direction , and has no concavo-convex parts uneven from the buttress surface other than the continuous grooves or continuous ribs extending continuously in the circumferential direction. In the circumferential direction, it is a band-like region that becomes a smooth surface,
The turbulent flow prevention region is 5 mm inward of the tread portion and inward of the sidewall portion along the tire axial direction and along the tire surface from the tire split surface formed by the mating surface of the mold for forming the tread portion and the sidewall portion. It includes at least a region near the split surface between 5 mm.
[0009]
In the invention of claim 1, the continuous groove or continuous rib is a tire split surface J formed by a mating surface of a mold for forming a tread portion and a sidewall portion when the tire is vulcanized and molded by the edges thereof. It is characterized by blinding generated burrs .
[0010]
In the invention of claim 2, the turbulent flow prevention region includes a position separating a distance of 1.2 times the tire ground contact half width WT from the tire equator outward in the tire axial direction, and a tire cross-sectional height H from the tire maximum diameter point. It is characterized in that it is arranged in a range region between a position that is 0.3 times as far as a distance inwardly in the radial direction .
[0011]
According to a third aspect of the present invention, the turbulent flow prevention region is characterized in that a region width W1 along the buttress surface in the tire axial direction is 20 mm or more.
[0012]
According to a fourth aspect of the present invention, the groove or rib extending continuously in the circumferential direction has a groove depth or a rib height of 1.5 mm or less.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a meridional sectional view when the pneumatic tire of the present invention is a passenger tire, and FIG. 2 is a perspective view showing a part thereof.
[0014]
1 and 2, a pneumatic tire 1 includes a tread portion 2 having a tread groove G provided on a tread surface 2S, sidewall portions 3 extending radially inward from both ends thereof, and radial directions of the sidewall portions 3. And a bead portion 4 positioned inward. A carcass 6 is bridged between the bead portions 4 and 4, and a belt layer 7 is disposed inside the tread portion 2 and outside the carcass 6.
[0015]
The carcass 6 is composed of one or more carcass plies 6A in this example, 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 portions 6b that are folded back and locked from the inside to the outside around the bead core 5 of the bead portion 4 at both ends of the body portion 6a straddling the bead portions 4 and 4. A bead apex rubber 8 for reinforcing the bead portion extending from the bead core 5 to the outer side in the tire radial direction is disposed between the main body portion 6a and the folded portion 6b.
[0016]
The belt layer 7 includes two or more belt plies 7A and 7B in which belt cords are arranged at an angle of, for example, 15 to 45 ° with respect to the tire circumferential direction. The tread portion 2 is reinforced with high rigidity by crossing at. A band layer 9 made of a band ply in which a band cord is spirally wound in the circumferential direction can be provided outside the belt layer 7 for the purpose of improving high-speed durability and steering stability as in this example.
[0017]
Next, the tread groove G disposed on the tread surface 2S includes a circumferential groove Gg extending continuously in the circumferential direction and a lug groove Gy in a direction intersecting with the circumferential groove Gg, and various tread patterns according to requirements. It is formed.
[0018]
In this embodiment, the buttress portion 10 which is a portion near the boundary between the tread portion 2 and the sidewall portion 3 continuously extends in the circumferential direction and is obvious from FIGS. The continuous turbulent flow prevention region 11 is formed without having .
[0019]
The turbulent flow prevention region 11 has a continuous groove 12 or a continuous rib extending continuously in the circumferential direction, and an uneven portion that is uneven from the buttress surface other than the continuous groove or continuous rib extending continuously in the circumferential direction. Reference numeral 13 denotes a band-like region that is eliminated and thereby becomes a smooth surface in the circumferential direction. In addition, although the case where only the continuous groove | channel 12 is distribute | arranged is illustrated in this example, both can also be distribute | arranged.
[0020]
The uneven portion 13 is a portion that is uneven from the buttress surface 10S. For example, as shown in FIG. 4, the ridge c1 with small pitch intervals, symbols, figures, etc. formed to improve the appearance, the trademark or tire size. There are a lettering c2 for marking information, a lug groove c3 extending from the tread pattern, an intermittent groove c4 intermittently 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.
[0021]
As the continuous groove 12 and the continuous rib that are allowed to be formed in the turbulent flow prevention region 11, the groove depth ha (in the case of the continuous rib) is shown in FIG. The rib height is preferably 1.5 mm or less, and if it exceeds 1.5 mm, the traveling wind from the traveling direction is affected and tends to cause turbulence. The continuous groove 12 and the continuous rib are generally used for decoration or when the tire is vulcanized and molded, the tire split surface J formed by the mating surface of the mold for forming the tread portion 2 and the sidewall portion 3. It is formed to blind the burrs generated in Accordingly, the groove width wa (rib width in the case of continuous ribs) 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 continuous groove 12 is formed by positioning the inner edge 12E in the radial direction of the continuous groove 12 on the tire split surface J for the purpose of hiding burrs.
[0022]
Here, as the turbulent flow prevention region 11, as shown in FIG. 1, a position P <b> 1 that separates a distance L <b> 1 1.2 times the tire ground contact half width WT from the tire equator C and the tire maximum diameter. A distance L2 that is 0.3 times the tire cross-section height H from a point CA (a point on the tread surface 2S where the tire diameter is maximum) is formed in a range region Y between a position P2 that is radially inwardly separated. Is preferred.
[0023]
This is because the range area Y of the buttress portion 10 is a part where the traveling wind is particularly strongly hit. By forming the turbulent flow prevention area 11 in the range area Y, the air resistance can be reduced more effectively. It is. In addition, when the turbulent flow prevention region 11 is provided on the inner side in the tire axial direction from the position P1, problems such as drainage properties and steering stability occur because the turbulent flow prevention region 11 is grounded when turning.
[0024]
At this time, the turbulent flow prevention region 11 preferably has a region width W1 along the buttress surface in the tire axial direction of 20 mm or more, and if it is less than 20 mm, the effect of reducing the air resistance tends not to be sufficiently exhibited. From the viewpoint of the effect of reducing air resistance, it is preferable that the turbulent flow prevention region 11 is formed over the entire range region Y, that is, the region width W1 is set equal to the width of the range region Y. Further, the turbulent flow prevention region 11 can be further widened and extended beyond the range region Y. However, in such a case, in addition to not expecting a further reduction effect, the formation area of the ridge c1 and lettering c2 is too small, which is disadvantageous in appearance performance.
[0025]
Here, “tire contact half width WT” means that from the tire equator C on the tread contact surface that can be grounded when a normal load is applied to a tire in a normal internal pressure state that is assembled with a normal rim and filled with a normal internal pressure. It means the distance in the tire axial direction to the tread contact edge.
[0026]
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, it is a standard rim for JATMA, “Design Rim” for TRA, or ETRTO. Means "Measuring Rim". The “regular internal pressure” is the air pressure specified by the tire for each tire. The maximum air pressure in the case of JATMA, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the case of TRA, If it is ETRTO, it is "INFLATION PRESSURE". “Regular load” is the load specified by the standard for each tire. If it is JATMA, it is 0.7 times the maximum load capacity. If it is TRA, it is listed in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”. 0.7 times the maximum value listed, and 0.7 times the "LOAD CAPACITY" for ETRTO.
[0027]
The tire cross-section height H is a distance in the radial direction from the bead base line BL to the tire maximum diameter point CA in the tire in the normal internal pressure state.
[0028]
Further, the turbulent flow prevention region 11 has a 5 mm inward tread portion and a 5 mm inward sidewall portion from the tire split surface J to the tire axial direction and along the tire surface in order to reduce air resistance. The split surface vicinity region Y1 is included at least.
[0029]
As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.
[0030]
【Example】
Tires of tire size 145 / 80R14 having the structure shown in FIGS. 1 and 2 were prototyped based on the specifications in Table 1, and the air resistance of each sample tire was measured and compared with each other.
[0031]
(1) Air resistance;
In an actual vehicle wind tunnel laboratory, the evaluation tire is mounted on a small front wheel drive vehicle with a displacement of 1300 cc, and the aerodynamic force when blowing at a speed equivalent to 100 km / h is measured using a floor balance under the wheel. The evaluation was made according to an index with the conventional example being 100. The smaller the number, the better.
[0032]
[Table 1]

[0033]
In the reference example , it can be confirmed that the formation of the turbulent flow prevention region can reduce the air resistance by 0.6% compared to the conventional example, which is useful for improving the fuel efficiency. The base Comparative Example 3 and the ratio of further eliminating the tread pattern, since the air resistance reducing effect of the same, and the observed formation of turbulence preventing region at the buttress portion is seen to be effective in reducing air resistance.
[0034]
【The invention's effect】
As described above, the present invention forms a turbulent flow prevention region in the buttress portion that does not have uneven portions other than grooves and ribs extending continuously in the circumferential direction, thereby reducing tire air resistance and reducing fuel consumption. It can contribute to the improvement of sex.
[Brief description of the 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 cross-sectional view showing a cross-sectional shape of a continuous groove.
FIG. 4 is a perspective view of a tire for explaining the prior art.
[Explanation of symbols]
2 tread portion 2S tread surface 3 sidewall portion 4 bead portion 10 buttress portion 10S buttress surface 11 turbulent flow prevention region 12 groove 13 uneven portion Y range region J tire split surface Y1 split region vicinity region

Claims (4)

A tread portion provided with a tread groove on the tread surface, a sidewall portion continuous radially inward from the tread portion, and a bead portion positioned 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 that is continuous without having a step with the tread surface is formed,
The turbulent flow prevention region has continuous grooves or continuous ribs extending continuously in the circumferential direction , and has no concavo-convex parts uneven from the buttress surface other than the continuous grooves or continuous ribs extending continuously in the circumferential direction. In the circumferential direction, it is a band-like region that becomes a smooth surface,
The turbulent flow prevention region is 5 mm inward of the tread portion and inward of the sidewall portion along the tire axial direction and along the tire surface from the tire split surface formed by the mating surface of the mold for forming the tread portion and the sidewall portion. Including at least a region near the split surface between 5 mm,
Moreover, when the tire is vulcanized, the continuous grooves and continuous ribs blind the burrs generated on the tire split surface J formed by the mating surfaces of the molds that form the tread portion and the sidewall portion. Pneumatic tire characterized by.   The turbulent flow prevention region includes a position separating a distance of 1.2 times the tire ground contact half width WT from the tire equator, and a distance of 0.3 times the tire cross-section height H from the tire maximum diameter point. The pneumatic tire according to claim 1, wherein the pneumatic tire is disposed in a range area between positions radially inwardly separated.   The pneumatic tire according to claim 2, wherein the turbulent flow prevention region has a region width W1 along the buttress surface in the tire axial direction of 20 mm or more. The pneumatic tire according to claim 1 , wherein the groove or rib extending in the circumferential direction has a groove depth or a rib height of 1.5 mm or less.

Images