JP2004306823A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of enlarging fall-down in applying a load to a ply body of a carcass, and reducing load noises while restraining excessive deterioration of steering stability such as heightening a damping and absorbing effect of vibrations from a tread part. <P>SOLUTION: A minimum thickness part P with minimum tire thickness between a bead part 4 and a side wall part 3 is provided in an area Q where a tire outer face is brought into contact with an arc part face R1a of a rim flange R1 at the time of applying a regular load. Bead apex rubber 8 is terminated in a tire radial direction inward of a minimum thickness part P, or cut in a radial direction inward and outward at the minimum thickness part P, and tire thickness T0 at the minimum thickness part P is set to 3-7 mm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４１】
第１発明に係わる実施例１、４、７のタイヤ、及び第２発明に係わる実施例２、３、５、６、８のタイヤは、従来的な比較例１のタイヤに比して、ロードノイズが低減しているのが確認できる。
【００４２】
【発明の効果】
叙上の如く本発明は、正規荷重付加状態においてタイヤ外面がリムフランジの円弧部面と接する領域内に、最小厚さ部を形成しているため、カーカスのプライ本体部の、荷重付加における倒れ込みを大きくすることができる。その結果、トレッド部からの振動の緩和吸収効果を高めることができ、操縦安定性の過度の低下を抑制しつつ、ロードノイズを低減することが可能になる。
【図面の簡単な説明】
【図１】第１の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】タイヤの正規荷重付加状態を説明する線図である。
【図４】タイヤ厚さとロードノイズ低減効果との関係を示す線図である。
【図５】第２の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６】そのビード部を拡大して示す断面図である。
【図７】従来技術を説明する線図である。
【符号の説明】
２ トレッド部
３ サイドウォール部
４ ビード部
５ ビードコア
６ カーカス
６Ａ カーカスプライ
６ａ プライ本体部
６ｂ プライ折返し部
８ ビードエーペックスゴム
Ｐ 最小厚さ部
Ｑ 領域
Ｒ 正規リム
Ｒ１ フランジ
Ｒ１ａ 円弧部面
Ｒｘ フランジ基線[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire with reduced road noise.
[0002]
[Prior art]
Road noise is one of the noises caused by tires. It is considered that this is because, when rolling, the impact received from the road surface vibrates the tread portion, and this vibration is transmitted from the rim to the chassis using the carcass as a medium and is generated as resonance sound inside the vehicle.
[0003]
Therefore, conventionally, in order to reduce road noise, measures such as adopting a low-rigidity cord in a carcass as a vibration medium or improving the vibration transmission characteristics by reducing the number of cords to be driven are taken. .
[0004]
[Problems to be solved by the invention]
However, the above-mentioned means has a limit because it causes a decrease in steering stability, such as a decrease in tire rigidity, and it has not been possible to reduce road noise to a sufficiently satisfactory level.
[0005]
In view of such a situation, as a result of research conducted by the present inventor, as shown exaggeratedly in FIG. 7, when a load is applied, the ply main body portion a1 of the carcass a uses the arc-shaped portion b1 of the rim flange b as a fulcrum to support the tire. It is deformed so that it falls down greatly in the axial direction.At this time, it is determined that the greater the fall, the easier it is to absorb and absorb the vibration from the tread, that is, the less likely it is for the vibration to be transmitted to the rim, thus reducing road noise. I got it.
[0006]
It has also been found that it is effective to form a portion for reducing the tire thickness in the region y in contact with the arc-shaped portion b1 in order to increase the inclination of the ply body portion a1. In addition, in such a case, it was also found that an excessive decrease in steering stability could be suppressed because the rigidity of the entire carcass was not reduced.
[0007]
Accordingly, the present invention provides a method for controlling the road noise while suppressing an excessive decrease in the steering stability, for example, it is possible to increase the collapse of the ply body of the carcass when a load is applied, and to enhance the effect of absorbing and absorbing vibration from the tread. It is an object of the present invention to provide a pneumatic tire capable of reducing the pressure.
[0008]
[Patent Document 1]
JP-A-5-131815 [Patent Document 2]
Japanese Patent Application Laid-Open No. 9-58226
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 of the present application is configured such that a ply body portion extending from a tread portion to a bead core of a bead portion through a sidewall portion is folded from the inside in the tire axial direction to the outside around the bead core. A pneumatic tire comprising a carcass having a carcass ply having a series of ply turnovers and a bead apex rubber extending radially outward from the bead core,
In the 5% internal pressure state where the rim is assembled to the regular rim and filled with 5% of the normal internal pressure,
In a region where the tire outer surface comes into contact with the arcuate surface of the flange of the regular rim when a regular internal pressure is applied and a regular load is applied, between the bead portion and the sidewall portion, between the tire outer surface and the inner surface. A minimum thickness part where the tire thickness is minimum is formed,
Moreover, the bead apex rubber terminates inward in the tire radial direction from the minimum thickness portion or is interrupted radially inward and outward at the minimum thickness portion,
The tire thickness T0 at the minimum thickness portion is set to 3 to 7 mm.
[0010]
According to the second aspect of the present invention, when the rim is assembled to the normal rim and 5% of the normal internal pressure is filled,
In a region where the tire outer surface comes into contact with the arcuate surface of the flange of the regular rim when a regular internal pressure is applied and a regular load is applied, between the bead portion and the sidewall portion, between the tire outer surface and the inner surface. A minimum thickness part where the tire thickness is minimum is formed,
Moreover, the bead apex rubber extends radially outward through the minimum thickness portion,
The tire thickness T0 at the minimum thickness portion is 3 to 9 mm, and the ratio TA / T0 between the tire thickness T0 and the bead apex rubber thickness TA at the minimum thickness portion is 0.5 times or less, and the difference is 0.5 or less. It is characterized in that T0-TA is 3 mm or more.
[0011]
In the invention according to claim 3, the regular rim is a 5 ° taper rim, and the minimum thickness portion is a position where a flange base line in the tire axial direction passing through a flange upper end of the rim intersects the tire outer surface. Features.
[0012]
The 5% internal pressure state is a state in which the contour of the tire is similar to the contour of the tire in the mold. In this specification, unless otherwise specified, the dimensions of each part of the tire are 5% A value specified in the internal pressure state.
[0013]
In this specification, the "regular rim" is a rim defined for each tire in a standard system including the standard on which the tire is based. For example, a standard rim for JATMA and a rim for TRA " Design Rim ”or“ Measurement Rim ”for ETRTO. The “regular internal pressure” is an air pressure defined for each tire according to the standard, and is the maximum air pressure for JATMA, and the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLASION PRESSURESRES” for TRA, In the case of ETRTO, it means "INFLATION PRESSURE". In the case of a tire for a passenger car, the pressure is 180 kPa. The "regular load" is a load defined for each tire by the standard. For JATMA, the maximum load capacity, and for TRA, the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLASION PRESSURESURES". , ETRTO means a load obtained by multiplying "LOAD CAPACITY" by 0.8.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to illustrated examples.
1 and 2 are drawings relating to a pneumatic tire according to the first invention of the present application, and FIG. 1 shows a state in which the pneumatic tire is assembled to a regular rim and filled with 5% of a normal internal pressure in a 5% internal pressure state. And FIG. 2 is an enlarged sectional view of the bead portion. 5 and 6 are drawings relating to the pneumatic tire according to the second invention. FIG. 5 is a meridional sectional view showing a 5% internal pressure state of the pneumatic tire, and FIG. 6 is an enlarged view of a bead portion. FIG.
[0015]
In FIG. 1, a pneumatic tire 1 </ b> A (hereinafter referred to as a tire 1 </ b> A) 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 carcass 6 inside the tread portion 2 and the carcass 6. And a belt layer 7 arranged in the radial direction.
[0016]
The belt layer 7 is composed of two or more, in this example, two belt plies 7A and 7B in which high elastic belt cords are arranged at an angle of, for example, 10 to 35 ° with respect to the tire circumferential direction. Each of the belt plies 7A and 7B enhances belt rigidity by intersecting the belt cords between the plies, and strongly reinforces substantially the entire width of the tread portion 2 with a tag effect. As the belt cord, a steel cord or a high-modulus organic fiber cord comparable thereto, such as an aromatic polyamide fiber, can be suitably used.
[0017]
For the purpose of enhancing high-speed durability, a band layer 9 in which band cords of organic fibers such as nylon are arranged at an angle of 5 degrees or less with respect to the circumferential direction is provided on the outer side of the belt layer 7 in the radial direction. Can be. As the band layer 9, a pair of left and right edge band plies covering only the outer end in the tire axial direction of the belt layer 7 and a full band ply covering substantially the entire width of the belt layer 7 can be used as appropriate. An example is shown in which a pair of edge band plies and one full band ply are used.
[0018]
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, in this example, one carcass ply 6A. Organic fiber cords such as are preferred. The carcass ply 6A includes a series of ply folded portions 6b that are folded around the bead core 5 from the inside to the outside in the tire axial direction at both ends of the ply main body 6a extending between the bead cores 5 and 5.
[0019]
A bead apex rubber 8 extending outward from the bead core 5 in the tire radial direction is disposed between the ply main body 6a and the ply turnover 6b. This bead apex rubber 8 is formed of a hard rubber having a rubber hardness (durometer A hardness) of 70 to 100 °. In the present example, the ply turn-up portion 6b has a radial height h1 from the bead base line BL that is greater than the radial height h2 of the bead apex rubber 8, and the bead apex rubber 8 has a radially outer height h2. After the end, it extends adjacent to the ply body 6a. In addition, the said "bead base line BL" means the tire axial line which passes through the rim diameter position defined by the standard on which the tire is based.
[0020]
In the present invention, in the normal load applied state Y2 (shown in FIG. 3) in which the tire 1A is filled with the normal internal pressure and the normal load is applied, the outer surface of the tire comes into contact with the arc surface R1a of the flange R1 of the normal rim. The minimum thickness portion P is formed in the region Q. In this example, the normal rim R is a well-known 5 ° taper rim in which the rim sheet R2 is inclined at 5 ° with respect to the tire axial direction, and the arc portion surface R1a rises from the rim sheet R2 via the heel portion. It is connected to the standing piece R1b of the flange R1 and curved in a convex arc outward in the tire axial direction and radially outward.
[0021]
Here, the “minimum thickness portion P” refers to the difference between the tire outer surface and the inner surface in the region range between the bead portion 4 and the sidewall portion 3 in the 5% internal pressure state Y1, as shown in FIG. Means the portion where the tire thickness T between them becomes minimum. That is, in an arc (inscribed circle) inscribing between the outer surface and the inner surface of the tire, it means a portion where the tire thickness T, which is the distance between the inner contacts, is minimum. Therefore, the tire thickness T gradually increases from the minimum thickness portion P toward the inside and outside in the tire radial direction.
[0022]
In the first invention, the bead apex rubber 8 terminates inward in the tire radial direction with respect to the minimum thickness portion P, or is interrupted radially inward and outward at the minimum thickness portion P, and has the minimum thickness. The thickness T0 of the tire at the portion P is regulated in the range of 3 to 7 mm.
[0023]
In this example, the bead apex rubber 8 extends from the bead core 5 at a small height, and the lower apex portion 8A having a substantially triangular cross-section and the lower apex portion 8A are separated from each other in a radial direction by a substantially streamline shape. The case where it is divided into the apex portion 8B is illustrated. At least a part of the separation region J of the lower upper apex portions 8A and 8B is formed in the region Q, and in the separation region J, the ply body portion 6a and the ply turnover portion 6b are adjacent to each other. I have.
[0024]
An inner liner rubber 10 forming the inner surface of the tire is additionally provided inside the ply body 6a, and the bead portion 4 rises along the ply turn-back portion 6b after passing through the bead bottom surface 4b from the bead toe 4a. A chafer rubber 11 for preventing rim displacement is provided. The chafer rubber 11 is in the form of a thin sheet having a thickness of 0.3 to 1.0 mm and having excellent wear resistance. The clinch apex rubber 12 of a hard rubber which forms the outer surface of the tire by, for example, extending radially outward from the bead heel is arranged in the bead portion 4. The clinch apex rubber 12 has a thin covering portion 12A that covers the chafer rubber 11, and a triangular apex cross-section extending radially outward beyond the region Q while continuing to the covering portion 12A and gradually increasing in thickness. The outer end is joined to the inner end of the sidewall rubber 3G. It should be noted that, if desired, the apex portion 12B alone can be formed. In such a case, the chafer rubber 11 is exposed to form a part of the tire outer surface.
[0025]
Here, in this example, the inner liner rubber 10, the ply main body 6a, the ply turn-up portion 6b, and the chafer rubber 11 have a substantially constant thickness over the entire length thereof, and the bead apex rubber 8 is provided. However, the minimum thickness portion P is formed in the region Q by being interrupted in the separation region J. In particular, in this example, a case where the bead apex rubber 8 is interrupted to form a concave portion 15 in which the inner surface of the tire is greatly depressed from the conventional inner surface Si of the tire (indicated by a dashed line in FIG. 2). In this example, the tire outer surface has substantially the same contour as the conventional tire outer surface.
[0026]
In the tire 1A in which the minimum thickness portion P is formed in the region Q as described above, the minimum thickness portion P is a weak point, and the bead portion 4 is greatly inclined outward on the flange R1 in the tire axial direction. Can be. As a result, the vibration and the vertical force from the tread portion are easily alleviated and absorbed, so that the vibration and the like are prevented from being transmitted to the rim, and the road noise can be reduced. In addition, since the rigidity of the entire carcass is not reduced, the steering stability can be prevented from being excessively reduced.
[0027]
At this time, the tire thickness T0 in the minimum thickness portion P needs to be 3 to 7 mm. This is because in the minimum thickness portion P, at least the inner liner rubber 10, the ply body portion 6a, and the ply folded portion 6b exist, but these members need to have a thickness of at least 3 mm or more. On the other hand, if it exceeds 7 mm, the bead portion 4 will not fall down sufficiently and the effect of reducing road noise cannot be sufficiently ensured.
[0028]
FIG. 4 shows the relationship between the tire thickness T0 and the road noise reduction effect based on the results of the experiment in Table 1 performed by the inventor. As shown in FIG. 4, it can be confirmed that an excellent road noise reduction effect is exhibited when the tire thickness T0 is 9 mm or less, particularly 7 mm or less.
[0029]
In the first aspect, if the bead apex rubber 8 is interrupted at the position of the minimum thickness portion P, the upper apex portion 8B is eliminated, and the bead apex rubber 8 is constituted only by the lower apex portion 8A. You may. Further, in the first invention, the thickness of at least one member of the inner liner rubber 10, the ply body 6a, the ply turn-up portion 6b, the chafer rubber 11, and the clinch apex rubber 12 is partially reduced, whereby It is also preferable to set the tire thickness T0 of the minimum thickness portion P smaller, in combination with the interruption of the bead apex rubber 8.
[0030]
Next, the tire 1B of the second invention will be described. The tire 1B of the second invention has substantially the same configuration as the tire 1A of the first invention except for the bead portion 4, and as shown in FIGS. P, and the bead apex rubber 8 extends radially outward in the tire through the minimum thickness portion P.
[0031]
The tire thickness T0 in the minimum thickness portion P is in the range of 3 to 9 mm, and the ratio TA / T0 between the tire thickness T0 and the thickness TA of the bead apex rubber 8 in the minimum thickness portion P. Is set to 0.5 times or less, and the difference T0-TA is set to 3 mm or more.
[0032]
In this example, the tire inner surface has substantially the same contour shape as the conventional tire inner surface, while the tire outer surface is larger than the conventional tire outer surface So in an arc shape within the range including the region Q. An example in which a concave portion 16 is formed is illustrated. The recess 16 partially reduces the thickness of at least one of the inner liner rubber 10, the ply body 6a, the bead apex rubber 8, the ply turn-back portion 6b, the chafer rubber 11, and the clinch apex rubber 12. Thus, the minimum thickness portion P is formed.
[0033]
In the present embodiment, in the concave portion 16, the inner liner rubber 10, the ply body 6a, the ply folded portion 6b, the chafer rubber 11, and the clinch apex rubber 12 have a substantially constant thickness, while the bead apex rubber 8 has the same thickness. In this case, the minimum thickness P is formed.
[0034]
Here, when the tire thickness T0 in the minimum thickness portion P exceeds 9 mm, or when the thickness TA of the bead apex rubber 8 in the minimum thickness portion P exceeds 0.5 times the tire thickness T0, the minimum The bending stiffness at the thickness portion P becomes excessive, the bead portion 4 falls insufficiently, and the road noise reduction effect cannot be sufficiently achieved. In order to form at least the inner liner rubber 10, the ply body 6a, and the ply turnup 6b, a thickness of 3 mm or more is required as described above. Therefore, in order to form a tire, it is necessary to set the tire thickness T0 and the difference T0-TA between the tire thickness T0 and the thickness TA to 3 mm or more.
[0035]
In order to ensure that the bead portion 4 falls down more, it is preferable that the minimum thickness portion P is formed at a position K where a flange base line Rx in the tire axial direction passing through the upper end of the flange R1 intersects the tire outer surface. .
[0036]
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.
[0037]
【Example】
Based on the specifications in Table 1, prototype tires for passenger cars with a tire size of 195 / 60R15 were produced, and the road noise performance of each trial tire was tested and compared. Except for the specifications in Table 1, the specifications are the same. FIG. 4 is a graph showing the relationship between the tire thickness T0 and the road noise at that time.
[0038]
In the table, the thickness Tb is the thickness from the bead apex rubber 8 to the inner surface of the tire at the minimum thickness portion P, the thickness Tc is the thickness from the bead apex rubber 8 to the clinch apex rubber 12, and the thickness Td is The thickness of the clinch apex rubber 12 to the tire outer surface and the thickness Te mean the maximum thickness of the clinch apex rubber 12 (shown in FIG. 6).
[0039]
(1) Road noise performance:
Each test tire is mounted on all the wheels of a passenger car (FF, 2000 cc) with a rim (15 × 6JJ) and internal pressure (200 kPa), and runs on a smooth road surface for road noise measurement at a speed of 60 km / h. The overall noise level dB (A) was measured at the position of the seat right ear, and is shown as a change from Comparative Example 1. A minus sign indicates that the road noise is lower than that of Comparative Example 1.
[0040]
[Table 1]

[0041]
The tires of the first, fourth, and seventh embodiments according to the first invention and the tires of the second, third, fifth, sixth, and eighth embodiments according to the second invention have a lower road load than the tire of the conventional comparative example 1. It can be confirmed that the noise has been reduced.
[0042]
【The invention's effect】
As described above, according to the present invention, in the normal load applied state, the tire outer surface forms a minimum thickness portion in a region in contact with the circular arc surface of the rim flange. Can be increased. As a result, the effect of absorbing and absorbing vibration from the tread portion can be enhanced, and road noise can be reduced while suppressing an excessive decrease in steering stability.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of a pneumatic tire according to the first invention.
FIG. 2 is an enlarged sectional view showing the bead portion.
FIG. 3 is a diagram illustrating a normal load application state of a tire.
FIG. 4 is a diagram showing a relationship between a tire thickness and a road noise reduction effect.
FIG. 5 is a sectional view showing an embodiment of the pneumatic tire of the second invention.
FIG. 6 is an enlarged sectional view showing the bead portion.
FIG. 7 is a diagram illustrating a conventional technique.
[Explanation of symbols]
2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 6A Carcass ply 6a Ply body part 6b Ply turnback part 8 Bead apex rubber P Minimum thickness part Q Area R Regular rim R1 Flange R1a Arc part surface Rx Flange base line

Claims (3)

A carcass having a carcass ply having a series of ply turn-up portions that are turned from the tread portion to the bead portion of the bead portion through the sidewall portion to the bead core, and are turned around from the bead core to the inside in the tire axial direction from the inside to the outside; A pneumatic tire comprising bead apex rubber extending radially outward from the bead core,
In the 5% internal pressure state where the rim is assembled to the regular rim and filled with 5% of the normal internal pressure,
In a region where the tire outer surface comes into contact with the arcuate surface of the flange of the regular rim when a regular internal pressure is applied and a regular load is applied, between the bead portion and the sidewall portion, between the tire outer surface and the inner surface. A minimum thickness part where the tire thickness is minimum is formed,
Moreover, the bead apex rubber terminates inward in the tire radial direction from the minimum thickness portion or is interrupted radially inward and outward at the minimum thickness portion,
A pneumatic tire characterized in that a tire thickness T0 at the minimum thickness portion is 3 to 7 mm. A carcass having a carcass ply having a series of ply turn-up portions that are turned from the tread portion to the bead portion of the bead portion through the sidewall portion to the bead core, and are turned around from the bead core to the inside in the tire axial direction from the inside to the outside; A pneumatic tire comprising bead apex rubber extending radially outward from the bead core,
In the 5% internal pressure state where the rim is assembled to the regular rim and filled with 5% of the normal internal pressure,
In a region where the tire outer surface comes into contact with the arcuate surface of the flange of the regular rim when a regular internal pressure is applied and a regular load is applied, between the bead portion and the sidewall portion, between the tire outer surface and the inner surface. A minimum thickness part where the tire thickness is minimum is formed,
Moreover, the bead apex rubber extends radially outward through the minimum thickness portion,
The tire thickness T0 at the minimum thickness portion is 3 to 9 mm, and the ratio TA / T0 between the tire thickness T0 and the bead apex rubber thickness TA at the minimum thickness portion is 0.5 times or less, and the difference is 0.5 or less. A pneumatic tire characterized in that T0-TA is 3 mm or more. The said normal rim is a 5 degree taper rim, and the said minimum thickness part is a position where the flange base line of the tire axial direction which passes the upper end of the flange of the said rim crosses a tire outer surface, The characterized by the above-mentioned. The pneumatic tire as described.

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