JP4408528B2 - Pneumatic tire - Google Patents

Description

【００２１】
次に、このような各タイヤを2000年度版ＪＡＴＭＡ ＹＥＡＲ ＢＯＯＫに記載されている標準リムに装着し、各タイヤにビード部がリムのビードシート部に完全に着座するまで内圧を充填した。このときの空気圧を前記表１にフィット圧（ kPa）として示す。
【００２２】
次に、前述の各タイヤに220kPaの内圧を充填して2600ccクラスの国産乗用車に装着した後、0〜400ｍのフル加速テストを行い、タイヤビード部とリムとのずれ量（mm）を測定した。その結果を前記表１に示す。
【００２３】
【発明の効果】
以上説明したように、この発明によれば、リム組み性と耐リムずれ性との双方を向上させることができる。
【図面の簡単な説明】
【図１】この発明の一実施形態を示すタイヤの子午線断面図である。
【図２】装着外側ビード部の拡大子午線断面図である。
【図３】装着内側ビード部の拡大子午線断面図である。
【符号の説明】
11…空気入りタイヤ 12、13…ビードコア
14、15…ビード部 16、17…サイドウォール部
18…トレッド部 D1、D2…内径
L1、L2…半径方向距離[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire having an improved bead portion in order to improve both rim assembly performance and rim displacement resistance.
[0002]
[Prior art]
In general, rim assemblability (including fit) and resistance to rim deviation are considered to be important performances for pneumatic tires. When the rim assembly property is poor, the pneumatic tire cannot be smoothly mounted on the rim, so that the roundness of the tire is reduced, or much labor and time are required for the rim assembly, On the other hand, when the resistance to rim displacement is poor, rim displacement may occur during traveling, and the separation and cord breakage may develop.
[0003]
Here, in order to improve the above-described rim assembly, it is only necessary to increase the inner diameter of the bead core to increase the radial distance from the bead core to the inner peripheral surface of the bead portion. The inner diameter of the bead core may be reduced to reduce the radial distance from the bead core to the inner peripheral surface of the bead portion. However, both of these are contradictory to each other as described above, and are contradictory.
[0004]
[Problems to be solved by the invention]
For this reason, in the past, the inner diameter of the bead core was set to a diameter in which the rim assembly property and the resistance to rim displacement were balanced, but such a pneumatic tire was not satisfactory in any performance and was dissatisfied. . In particular, with increasing performance and output of vehicles in recent years, pneumatic tires have become wider and flattened so as not to lose high output torque, so the force generated between the bead portion and the rim is large. As a result, rim displacement is likely to occur.
[0005]
An object of the present invention is to provide a pneumatic tire capable of improving both the rim assembly property and the rim displacement resistance.
[0006]
[Means for Solving the Problems]
Such a purpose is that a pair of bead portions each having a bead core embedded therein and having the same inner diameter, a pair of sidewall portions extending from the bead portions toward the outer side in a substantially radial direction, and radially outer ends of the sidewall portions. In a pneumatic tire having a tread portion that is connected to the inside of the bead core, the inner diameter D1 of the bead core positioned on the outer side when mounted on the vehicle is smaller than the inner diameter D2 of the bead core positioned on the inner side of the bead core . The radial distance from the end to the inner peripheral surface of the bead portion is reduced from the inner side to the outer side of the mounting, and the radial distance L1 from the inner end surface of the mounting outer bead core to the inner peripheral surface of the bead portion is 4.5 mm or less. This can be achieved.
[0007]
When the vehicle travels, the greatest force is generated between the rim and the pneumatic tire between the bead portion on the outer side of the pneumatic tire that is located on the outer side of the turn and the rim when the vehicle turns. ,It is said. This means that rim displacement is most likely to occur between the bead portion on the outer side of the mounting and the rim. Therefore, in the present invention, the inner diameter D1 of the bead core positioned on the outer side of the mounting is the same as that of the bead core positioned on the inner side of the mounting. By making it smaller than the inner diameter D2, the radial distance from the radially inner end of the bead core to the inner peripheral surface of the bead portion is made smaller from the inner side of the mounting to the outer side of the mounting. This effectively suppresses the rim shift at However, even if the above relationship is satisfied, if the radial distance L1 from the radially inner end of the attached outer bead core to the inner peripheral surface of the bead portion exceeds 4.5 mm, a large rim shift occurs. This radial distance must not exceed 4.5mm.
[0008]
On the other hand, for the inner bead core with a relatively small force between the rim and the pneumatic tire, the inner diameter D2 is larger than the inner diameter D1 of the bead core located on the outer side of the mounting, so the aforementioned radial distance is also large. This improves the rim assembly. In this way, the bead portion on the outer side of the mounting is resistant to rim displacement, the rim assembly property to the bead portion on the inner side of the mounting, and each bead portion is assigned a role, so both the rim displacement resistance and the rim assembly property are improved. be able to.
[0009]
Moreover, if comprised as described in Claim 2, both rim shift | offset | difference resistance and rim | limb assembly property can be improved effectively.
Furthermore, if constituted as in claim 3, it is possible to prevent deterioration of the rim assembly.
Moreover, if comprised as described in Claim 4, both rim shift | offset | difference resistance and rim | limb assembly property can be improved effectively.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In FIGS. 1 and 2, 11 is a pneumatic radial tire for high-speed running. This tire 11 has a pair of bead portions 14 and 15 in which bead cores 12 and 13 are embedded, respectively, and a substantially radius from these bead portions 14 and 15. A pair of sidewall portions 16, 17 extending outward in the direction, and a substantially cylindrical tread portion 18 connecting the outer ends in the radial direction of the sidewall portions 16, 17 are provided. Here, the bead cores 12 and 13 are configured by winding a rubber-coated single wire cord 19 a plurality of times in a spiral manner, and by superposing a plurality of such spiral windings in a radial direction, and the overall cross-sectional shape is Presents a rectangle.
[0011]
21 is a rim on which the tire 11 is mounted. The rim 21 is located on the outer side (side away from the center in the width direction of the vehicle) and on the inner side (close to the center in the width direction of the vehicle). A bead seat portion 23 positioned on the side), and the bead seat portion 22 is seated with an outer bead portion 14 and the bead seat portion 23 is seated with an inner bead portion 15. An annular drop portion 24 is provided on the rim 21 between the bead seat portions 22 and 23 and is recessed inward in the radial direction.
[0012]
Reference numeral 27 denotes a toroidal carcass layer extending from the bead core 12 to the bead core 13, and the carcass layer 27 is composed of at least one carcass ply 28. Then, both end portions in the width direction of the carcass ply 28 are folded around the bead cores 12 and 13 from the inner side in the axial direction toward the outer side in the axial direction. In the carcass ply 28, there are a plurality of cords extending in a direction substantially orthogonal to the tire equator plane E (inclined at an angle of 80 to 90 degrees with respect to the tire equator plane E), that is, in a radial direction. Buried, these cords are composed of organic fibers such as polyethylene terephthalate cords.
[0013]
Reference numeral 30 denotes a tread arranged on the outer side in the radial direction of the carcass layer 27, and a belt layer 31 is arranged between the tread 30 and the carcass layer 27. The belt layer 31 is formed by laminating a plurality of belt plies 32, and a plurality of parallel cords made of non-stretchable, for example, steel are embedded in each belt ply 32. . The cords embedded in the belt plies 32 are inclined at an angle of 20 to 45 degrees with respect to the tire equatorial plane E, and at least two layers of the belt plies 32 are inclined in opposite directions and intersect each other.
[0014]
And when such a tire 11 and rim 21 are mounted on a vehicle and run, the rim 21 and the tire 11, more specifically, the circumferential direction between the bead seat portions 22, 23 and the inner peripheral surface of the bead portions 14, 15; Although a lateral sliding force is generated, it is said that such a force is greatest between the outer bead portion 14 and the bead seat portion 22 of the tire 11 that is located on the outer side of the turn when the vehicle is turning. Yes. This means that rim displacement is most likely to occur between the bead portion 14 and the bead seat portion 22 on the outside of the mounting.
[0015]
Therefore, in this embodiment, the inner diameter (diameter) D1 of the bead core 12 positioned on the outer side of the mounting is smaller than the inner diameter D2 of the bead core 13 positioned on the inner side of the mounting while maintaining the inner diameter of the bead portions 14 and 15 constant. That is, D1 <D2. As a result, the radial distances L1 and L2 from the radially inner ends of the bead cores 12 and 13 to the inner peripheral surfaces of the bead portions 14 and 15 are smaller on the wearing outer side than on the wearing inner side, that is, L1 <L2, thereby The rim displacement between the bead portion 14 and the rim 21 is suppressed. However, even if the above relationship is satisfied, if the radial distance L1 exceeds 4.5 mm, a large rim displacement occurs in the bead portion 14 on the outer side of the mounting, so this radial distance L1 is 4.5 mm or less. Must.
[0016]
On the other hand, the inner radius D2 of the inner bead core 13 with a relatively small force between the rim 21 and the tire 11 is larger than the inner diameter D1 of the outer bead core 12, so the aforementioned radial distance L2 is the radial direction. The distance becomes larger than the distance L1, which improves rim assembly. In this way, the bead portion 14 on the outer side of the mounting is resistant to rim displacement, the rim assembly property on the inner bead portion 15 is assigned to each bead portion, and both the rim displacement resistance and the rim assembly property are improved. Can be made.
[0017]
Here, the aforementioned inner diameters D1 and D2 and the radial distances L1 and L2 are values measured on radial lines passing through the center of the bead cores 12 and 13 in the width direction. The difference between the inner diameter D1 and the inner diameter D2 is preferably in the range of 1.5 to 3.0 mm. The reason for this is that if the difference between the inner diameter D1 and the inner diameter D2, that is, the value of D2−D1 is less than 1.5 mm, the role sharing in each of the bead portions 14 and 15 described above is not sufficient. Both of the assembling properties cannot be improved sufficiently. On the other hand, if it exceeds 3.0 mm, the inner diameter D1 of the mounting outer bead core 12 becomes too small, or the inner diameter D2 of the mounting inner bead core 13 becomes too large. This is because the rim assembly property at the mounting outer bead portion 14 may be deteriorated, or the rim displacement resistance at the mounting inner bead portion 15 may be deteriorated. Both rim assembly properties can be effectively improved.
[0018]
In addition, the radial distance L1 must be 4.5 mm or less as described above, but if the value is less than 3.0 mm, the rim assembly property in the mounting outer bead portion 14 may be deteriorated. L1 is preferably 3.0 mm or more. Furthermore, the radial distance L2 from the inner radial end of the mounting inner bead core 13 to the inner peripheral surface of the mounting inner bead portion 15 is preferably in the range of 4.0 mm to 6.0 mm. The reason is that if the radial distance L2 is less than 4.0 mm, the rim assembly property in the mounting inner bead portion 15 may be deteriorated, whereas if the radial distance L2 exceeds 6.0 mm, This is because the rim displacement resistance in the mounting inner bead portion 15 may be deteriorated. However, if the rim displacement resistance is within the above-described range, both the rim displacement resistance and the rim assembly property can be effectively improved.
[0019]
【Example】
Next, test examples will be described. In this test, the radial distance L1 at the mounting outer bead portion is smaller than the radial distance L2 at the mounting inner bead portion (the inner diameter D1 of the mounting outer bead core is smaller than the inner diameter D2 of the mounting inner bead core), and The embodiment tire in which the value of the radial distance L1 is 4.5 mm or less, the comparative tire 1 in which the radial distances L1, L2 are the same value, and the radial distance L1 exceeds 4.5 mm, The comparative tire 2 in which the radial distances L1 and L2 have the same value and the radial distance L1 is 4.5 mm or less, and the radial distance L1 is smaller than the radial distance L2, but the radial distance A comparative tire 3 having an L1 value exceeding 4.5 mm was prepared. Here, the values of the radial distances L1 and L2 (mm) of each tire and the difference between the inner diameter D1 of the mounting outer bead core and the inner diameter D2 of the mounting inner bead core, that is, D2−D1 (mm) are shown in Table 1 below. . Here, the size of each tire was 245/45 ZR17.
[0020]
[Table 1]

[0021]
Next, each of these tires was mounted on a standard rim described in the 2000 edition JATMA YEAR BOOK, and the internal pressure was filled in each tire until the bead portion was completely seated on the bead seat portion of the rim. The air pressure at this time is shown as fit pressure (kPa) in Table 1.
[0022]
Next, after filling each tire with an internal pressure of 220 kPa and mounting it on a 2600cc class domestic passenger car, a full acceleration test of 0 to 400 m was performed to measure the deviation (mm) between the tire bead and the rim. . The results are shown in Table 1.
[0023]
【The invention's effect】
As described above, according to the present invention, it is possible to improve both the rim assembly property and the rim displacement resistance.
[Brief description of the drawings]
FIG. 1 is a meridian cross-sectional view of a tire showing an embodiment of the present invention.
FIG. 2 is an enlarged meridian cross-sectional view of a mounting outer bead portion.
FIG. 3 is an enlarged meridian cross-sectional view of a mounting inner bead portion.
[Explanation of symbols]
11 ... Pneumatic tire 12, 13 ... Bead core
14, 15 ... Bead part 16, 17 ... Side wall part
18 ... Tread part D1, D2 ... Inner diameter
L1, L2 ... Radial distance

Claims (4)

A pair of bead portions having bead cores embedded therein and having the same inner diameter, a pair of sidewall portions extending substantially radially outward from these bead portions, and a tread portion connecting the radially outer ends of these sidewall portions. In the provided pneumatic tire, the inner diameter D1 of the bead core positioned on the outer side of the bead core when mounted on the vehicle is smaller than the inner diameter D2 of the bead core positioned on the inner side of the bead, so The radial distance to the peripheral surface is reduced from the inner side to the outer side of the mounting, and the radial distance L1 from the inner radial surface of the outer bead core to the inner peripheral surface of the bead portion is set to 4.5 mm or less. Pneumatic tire.     The pneumatic tire according to claim 1, wherein a difference between an inner diameter D1 of the outer bead core and an inner diameter D2 of the inner bead core is 1.5 to 3.0 mm.     The pneumatic tire according to claim 1, wherein a radial distance L1 from the radially inner end of the attached outer bead core to the inner peripheral surface of the bead portion is 3.0 mm or more.     The pneumatic tire according to claim 1, wherein a radial distance L2 from a radially inner end of the mounting inner bead core to an inner peripheral surface of the bead portion is in a range of 4.0 mm to 6.0 mm.

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