JP2004017778A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the stability of maneuvering while preventing the performance of FV and road noise reduction from degrading. <P>SOLUTION: A projection 10 is formed on a bead outside surface S3 faced to a rim flange R2 in a manner that the projection 10 extends along a circumferential direction of a tire and are in pressure-contact with the flange R2. The projection 10 has the height La from a bead base line BL of a radial inner end 10e set to 15 to 18 mm, the radial projection width W set to 10 to 15 mm, and the projection height from the bead outside surface S3 to 1.0 to 2.0 mm. In a rim assembly state, the rising angle θ from a bead bottom surface S1 on the surface S3 is set to 80 to 90°. <P>COPYRIGHT: (C)2004,JPO

Description

【００２８】
テストの結果、実施例のものは、従来例と比べ、フォースバリエーション（ＦＶ）及びロードノイズ性能を維持しながら操縦安定性を向上しうるのが確認できる。
【００２９】
【発明の効果】
叙上の如く本発明は、ビード外側面に、リムフランジ上部との接触圧を高める突起部を所定位置かつ所定寸法で形成しているため、フォースバリエーション（ＦＶ）及びロードノイズ性能の悪化を抑えながら操縦安定性を向上することができる。
【図面の簡単な説明】
【図１】本発明の空気入りタイヤの一実施例を示す断面図である。
【図２】そのビード部を拡大して示す断面図である。
【図３】リム組状態におけるビード部を拡大して示す断面図である。
【図４】従来タイヤのビード部を説明する断面図である。
【符号の説明】
４　　　ビード部
１０　　突起部
１０Ｓ　突起部の外面
ＢＬ　　ビードベースライン
Ｒ　　　リム
Ｒ２　　リムフランジ
Ｓ１　　ビード底面
Ｓ３　　ビード外側面[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire having improved steering stability while suppressing deterioration in force variation (FV) and road noise performance.
[0002]
2. Description of the Related Art
Conventionally, in a pneumatic tire, as shown schematically in FIG. 4, the contour of the bead outer surface as is formed along the contour of the rim inner surface Rs, and the bead portion a is brought into close contact with the rim R without any gap. The deterioration of variation (FV) is suppressed.
[0003]
However, in such a structure, the contact pressure between the bead portion a and the rim flange R2 is low. Therefore, in order to obtain sufficient steering stability or to improve the steering stability, the rigidity of the bead portion is greatly increased. However, there is a problem that the sound and vibration performance is impaired and the road noise performance particularly on the low frequency side (around 250 Hz) is deteriorated.
[0004]
Therefore, the present invention is based on the provision of a projection on the outer surface of the bead to increase the contact pressure with the rim flange, and a pneumatic pump capable of improving steering stability while suppressing deterioration in force variation (FV) and road noise performance. It aims to provide tires.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 of the present application is a pneumatic tire mounted on a rim,
The bead portion of the pneumatic tire protrudes from the bead outside surface facing the rim flange, continuously extends in the tire circumferential direction, and presses against the rim flange to separate the bead outside surface from the rim flange. With a projection to make it
The protrusion has a height La from the bead base line at the inner end in the radial direction of 15 to 18 mm, a width W of the protrusion in the radial direction of 10 to 15 mm, and a height T of protrusion from the outer surface of the bead of 1 mm. 0.0 to 2.0 mm,
In the rim assembly state mounted on the rim, a rising angle θ of the bead outer surface from the bead bottom surface is set to 80 to 90 °.
[0006]
The invention according to claim 2 is characterized in that the outer surface of the projection is parallel to the outer surface of the bead.
[0007]
In the invention according to claim 3, the rim is a standard rim.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to illustrated examples.
FIG. 1 is a cross-sectional view when the pneumatic tire of the present invention is a tire for a passenger car having a tire size of 175 / 65R14, FIG. 2 is a cross-sectional view showing an enlarged bead portion, and FIG. 3 is a bead portion in a rim assembly state. It is sectional drawing which expands and shows.
[0009]
In FIG. 1, a pneumatic tire 1 includes a carcass 6 extending from a tread portion 2 to a bead core 5 of a bead portion 4 through a sidewall portion 3, and a belt disposed inside the tread portion 2 and outside the carcass 6. And a layer 7.
[0010]
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, and in this example, one carcass ply 6A. As the carcass cord, nylon, rayon, polyester, or the like is used. Is preferably employed. The carcass ply 6A is provided with a series of ply folds 6b which are turned around from the inside of the bead core 5 to the outside at both ends of the ply main body 6a straddling the bead cores 5, 5. A bead apex rubber 8 for reinforcing beads is provided between the portion 6b.
[0011]
The belt layer 7 is composed of two or more, in this example, two belt plies 7A and 7B in which highly elastic belt cords are arranged at an angle of, for example, 10 to 35 ° with respect to the tire circumferential direction. The belt plies 7A and 7B are superposed with different inclinations so that the belt cords intersect each other between the plies, thereby increasing the belt rigidity and reducing the substantially entire width of the tread portion 2 with a tag effect. Strongly reinforced. As the belt cord, a steel cord or a high modulus organic fiber cord such as an aromatic polyamide fiber comparable thereto is preferably used.
[0012]
Next, as shown in FIG. 2, the bead portion 4 rises and faces the rim flange R2 via a bead bottom surface S1 seated on the rim seat R1 of the rim R, and an arc-shaped bead heel surface S2 on the bead bottom surface S1. And a bead outside surface S3.
[0013]
The rim R has a well-known structure in which a rim flange R2 is raised on a rim sheet R1 via an arc-shaped heel portion R3, and is a standard rim defined in a standard system including standards based on tires, that is, a JATMA standard (Japan). ) For the standard rim, the TRA standard (US) for "Design Rim", and the ETRTO standard (Europe) for "Measuring Rim". In this example, the case where the rim sheet R1 is a so-called 5 ° deep bottom rim that is inclined at an angle α of about 5 degrees with respect to the tire axial line is illustrated.
[0014]
The bead outer surface S3 is a straight line extending substantially perpendicularly to the tire axial direction from the bead heel surface S2 when the pneumatic tire 1 is held in a non-rim assembled state with the bead width Wa adjusted to the rim width Wr. And a curved portion S3b which forms a concave arc shape having a center outside the tire and connects the base portion S3a and the sidewall portion 3. In this non-rim assembled state, in this example, the bead outer surface S3 is formed along the contour of the rim flange R2.
[0015]
In the present embodiment, in order to improve the steering stability while suppressing the deterioration of the force variation (FV) and road noise performance, the bead outer surface S3 projects from the bead outer surface S3 and is continuous with the tire circumferential direction. A protrusion 10 is provided to extend the bead outer surface S3 from the rim flange R2 by extending and pressing the upper portion of the rim flange R2.
[0016]
Here, in the protruding portion 10, the height La of the radially inner end 10e from the bead base line BL is 15 to 18 mm, the radially protruding width W is 10 to 15 mm, and the protruding portion 10e protrudes from the bead outer surface S3. It is important that the height T be 1.0 to 2.0 mm. The protruding portion 10 is formed of a hard clinch apex rubber 4G having a rubber hardness (durometer A hardness) of 60 to 80 degrees which forms the bead skin.
[0017]
In addition, the said "bead base line BL" means the tire axial direction line which passes the bead diameter position defined by the standard based on a tire.
[0018]
As shown in FIG. 3, in the bead portion 4 provided with such a protruding portion 10, the protruding portion 10 is strongly pressed against the upper portion of the rim flange R2 in the rim assembled state, and the movement of the bead portion 4 is strongly restrained. As a result, steering stability can be improved. In addition, a force that strongly presses the bead bottom surface S1 and the bead heel surface S2 against the rim sheet R1 and the heel portion R3 due to the pressure contact with the rim flange R2 acts, so that the steering stability is further improved and the bead portion 4 is moved to the rim R. Is stabilized, and deterioration of the force variation (FV) can be prevented.
[0019]
If the protruding height T is less than 1.0 mm and the height La exceeds 18 mm, the effect of improving steering stability becomes insufficient, such as insufficient press contact with the upper portion of the rim flange R2. Is greater than 2.0 mm and the height La is less than 15 mm, the air remaining between the bead outer surface S3 and the rim flange R2 becomes excessively large and the seating becomes unstable, and the force variation (FV) Causes deterioration.
[0020]
On the other hand, if the projection width W is less than 10 mm, the pressure contact with the rim flange R2 cannot be sufficiently performed, so that the effect of improving the steering stability becomes too small. On the other hand, if it exceeds 15 mm, the rigidity of the bead portion increases, leading to deterioration of road noise.
[0021]
In order to effectively exhibit the operation and effect (improving the steering stability while suppressing the deterioration of the force variation (FV) and road noise performance) of the present application, the bead bottom surface S1 of the bead outer surface S3 in the rim assembled state. It is also important that the rising angle θ from the bottom, that is, the rising angle θ from the bead bottom surface S1 of the base S3a be in the range of 80 to 90 °. If the angle θ is less than 80 °, sufficient pressure contact with the upper portion of the rim flange R2 cannot be obtained. Conversely, if the angle θ is greater than 90 °, the remaining air becomes excessive and adversely affects the force variation (FV).
[0022]
Preferably, the protrusion 10 has an outer surface 10S formed in parallel with the bead outer surface S3 in order to facilitate contact with the rim flange R2.
[0023]
As described above, particularly preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to the illustrated embodiments, and can be implemented in various forms.
[0024]
【Example】
Prototype tires of the structure shown in Fig. 1 with a tire size of 175 / 65R14 were manufactured based on the specifications in Table 1, and the steering stability, ride comfort, road noise performance, and force variation of each test tire were measured and compared. did. Except for the specifications in Table 1, the specifications were the same.
[0025]
(1) Steering stability performance, ride comfort performance;
The test tires were mounted on four wheels of a vehicle (1000cc, FF vehicle) with a rim (5.5J × 14) and an internal pressure (220kPa), and the steering stability performance when running on a tire test course on dry asphalt road surface ( Rigidity and steering wheel responsiveness) and ride comfort performance were evaluated by a ten-point method with six points in the conventional example by sensory evaluation of the driver. The higher the value, the better.
[0026]
(2) Road noise performance;
Using the vehicle, a rough asphalt road for noise evaluation was run at a speed of 50 km / h, and the overall noise level was measured at the left ear of the driver's seat. The higher the value, the better.
[0027]
(3) Force variation;
Lateral force variation is measured according to JASOc607, and the maximum value is indicated by an index with the conventional example being 100. The higher the value, the better.
[Table 1]

[0028]
As a result of the test, it can be confirmed that the embodiment can improve the steering stability while maintaining the force variation (FV) and the road noise performance as compared with the conventional example.
[0029]
【The invention's effect】
As described above, according to the present invention, the protrusions for increasing the contact pressure with the upper portion of the rim flange are formed at predetermined positions and at predetermined dimensions on the outer surface of the bead, so that deterioration of force variation (FV) and road noise performance is suppressed. However, the steering stability can be improved.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of a pneumatic tire according to the present invention.
FIG. 2 is an enlarged sectional view showing the bead portion.
FIG. 3 is an enlarged sectional view showing a bead portion in a rim assembled state.
FIG. 4 is a cross-sectional view illustrating a bead portion of a conventional tire.
[Explanation of symbols]
4 Bead portion 10 Projection portion 10S Outside surface of projection portion BL Bead base line R Rim R2 Rim flange S1 Bead bottom surface S3 Bead outside surface

Claims (3)

A pneumatic tire attached to the rim,
The bead portion of the pneumatic tire protrudes from the bead outside surface facing the rim flange, continuously extends in the tire circumferential direction, and presses against the rim flange to separate the bead outside surface from the rim flange. With a projection to make it
The protrusion has a height La from the bead base line at the inner end in the radial direction of 15 to 18 mm, a width W of the protrusion in the radial direction of 10 to 15 mm, and a height T of protrusion from the outer surface of the bead of 1 mm. 0.0 to 2.0 mm,
A pneumatic tire, wherein a rising angle θ of the outer side surface of the bead from the bottom surface of the bead is 80 to 90 ° in a rim assembly state mounted on the rim. The pneumatic tire according to claim 1, wherein an outer surface of the protrusion is parallel to the outer surface of the bead. The pneumatic tire according to claim 1, wherein the rim is a standard rim.

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