JP2004268768A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simultaneously achieve the acquisition of operational stability, the suppression of the increase of noise after use, and the suppression of the deterioration of the comfortable riding after use. <P>SOLUTION: Although the volume of a bead filler 22 is reduced compared with a conventional volume by setting the height BH of the bead filler 22 within the range from 20% to 35% of the height SH in the cross section of a tire, the reduction in the stiffness due to a reduction in the volume of the bead filler 22 is supplemented by a reinforcing layer 44. Therefore, the operational stability is secured. Although the hardness of the bead filler 22 increases further with the use of the tire, the volume of the bead filler 22 is small compared with the conventional. Therefore, the degree of the noise and the deterioration of the comfortable riding can be reduced even if the hardness of the bead filler 22 is increased. The hardening of the reinforcing layer 44 due to its degradation has a small effect on the noise and comfortable riding because the reinforcing layer 44 is thin compared with the bead filler 22 and has a small effect on its bending stiffness. Therefore, the operational stability, the noise, and the comfortable riding are maintained in a well balanced state from an initial stage to a middle stage and after that. Therefore, the acquisition of operational stability, the suppression of the increase of noise after use, and the suppression of the deterioration of comfortable riding after use can be simultaneously achieved. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００８８】
【表２】

【００８９】
【表３】

【００９０】
【表４】

【００９１】
【表５】

上記表１〜５に示すように、本発明の適用された実施例のタイヤは、劣化後の性能低下が、従来例、及び比較例に対して小さいことが分かる。
【００９２】
【発明の効果】
本発明の空気入りタイヤは上記構成としたので、操縦安定性の確保、使用後の騒音、及び乗心地性能の低下抑制を同時に実現することができる、という優れた効果を有する。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る空気入りタイヤの断面図である。
【図２】補強層端部付近の断面図である。
【図３】従来例に係る空気入りタイヤの断面図である。
【符号の説明】
１０ 空気入りタイヤ
１２ ビードコア
１５ カーカスプライ
１６ カーカスプライ
１７ ビード部
２２ ビードフィラー
４４ 補強層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire capable of simultaneously ensuring steering stability, suppressing noise deterioration after use, and suppressing reduction in ride comfort after use.
[0002]
[Prior art]
The bead portion of the pneumatic tire is provided with a bead filler made of hard rubber, and the height of the bead filler is generally set to 40 to 50% of the tire section height (for example, see Patent Document 1). .).
[0003]
Further, the pneumatic tire has a problem that its rubber is deteriorated by use.
[0004]
For example, the hardness of the rubber of the bead filler has been further increased by the use of the tire, and as a result, it has been one of the main factors of the noise and the deterioration of the riding comfort.
[0005]
[Patent Document 1]
JP-A-11-116735
[Problems to be solved by the invention]
Therefore, it is conceivable to reduce the volume of the bead filler in order to suppress the noise and the reduction in ride comfort.However, this leads to a decrease in the rigidity of the bead portion, and the effect on steering stability and durability cannot be ignored. Therefore, the volume could not be easily reduced.
[0007]
In view of the above, the present invention provides a pneumatic tire that can simultaneously realize steering stability, suppress deterioration of noise after use, and suppress deterioration of ride comfort after use. The purpose is to do.
[0008]
[Means for Solving the Problems]
The pneumatic tire according to claim 1, wherein at least one of the pneumatic tires, which straddles between a pair of bead portions in a toroidal shape, is wound around the bead core arranged in the bead portion in the width direction from the inside to the outside in the tire width direction. A carcass ply, a body portion of the carcass ply that straddles the pair of bead portions in a toroidal shape, and a carcass ply rewinding portion wound around the bead core; And a bead filler set within a range of 20 to 35% of the height of the tire cross section, and a bead filler that is disposed outside the rewinding portion of the carcass ply in the tire width direction and substantially equal to the bead filler. It is made of rubber having the same hardness, and extends at least outward in the tire radial direction from the tire radial outer end of the bead filler. It is characterized by having a reinforcement layer formed to be thinner than the filler.
[0009]
Next, the operation of the pneumatic tire according to claim 1 will be described.
[0010]
In the pneumatic tire according to claim 1, the volume of the bead filler is reduced by setting the height of the bead filler within a range of 20 to 35% of the tire cross-sectional height, as compared with the related art. Since the reinforcement layer compensates for the decrease in rigidity due to the reduction in steering, steering stability is ensured.
[0011]
The bead filler is made of hard rubber and deteriorates with the use of tires to increase the hardness.However, since the volume is reduced compared to the conventional type, even if the hardness increases, the noise and the ride performance will be reduced. The degree of reduction can be reduced.
[0012]
Hardening due to deterioration of the reinforcing layer itself is thinner than the bead filler and has less effect on bending rigidity, so it has little effect on noise and ride comfort, and it is stable in operation after use. The balance of performance, noise, and ride quality is maintained.
[0013]
Therefore, according to the pneumatic tire of the first aspect, it is possible to simultaneously secure the steering stability and suppress the decrease in the riding comfort after use.
[0014]
Therefore, it is possible to simultaneously secure the steering stability, suppress the deterioration of the noise after use, and suppress the deterioration of the ride comfort after use.
[0015]
Here, when the height of the bead filler is less than 20% of the tire cross-sectional height, the rigidity of the tire side region is insufficient, and the steering stability and durability cannot be sufficiently secured.
[0016]
On the other hand, if the height of the bead filler exceeds 35% of the tire cross-section height, the rigidity of the tire side region becomes too high, and the original object of suppressing noise and reduction in ride comfort cannot be achieved.
[0017]
Note that the height of the bead filler is based on the position of the bead heel as in the case of measuring the tire cross-sectional height, and is a dimension measured outward from the reference in the tire radial direction.
[0018]
The term "substantially equal to the hardness of the rubber" as used herein means that the hardness is within a range of ± 5 degrees.
[0019]
The invention according to claim 2 is the pneumatic tire according to claim 1, wherein the hardness of the rubber of the reinforcing layer is in a range of 90 to 100 degrees.
[0020]
Next, the operation of the pneumatic tire according to claim 2 will be described.
[0021]
By setting the hardness of the rubber of the reinforcing layer within the range of 90 to 100 degrees, it is possible to suppress noise after use and suppress a decrease in ride comfort, and ensure steering stability at a high level.
[0022]
If the hardness of the rubber of the reinforcing layer is less than 90 degrees, it becomes difficult to secure the steering stability.
[0023]
On the other hand, when the hardness of the rubber of the reinforcing layer exceeds 100 degrees, it becomes difficult to secure ride comfort.
[0024]
In the present invention, the hardness of the rubber is a hardness according to a spring type (durometer hardness) of JIS K6253.
[0025]
According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, the reinforcing layer has a portion near the tire radial inner end and a portion near the tire radial outer end of the bead filler. The overlap dimension between the vicinity of the tire radial inner end of the reinforcing layer and the vicinity of the tire radial outer end of the bead filler is set to at least 5 mm.
[0026]
Next, the operation of the pneumatic tire according to claim 3 will be described.
[0027]
If a part of the reinforcing layer on the tire radial inner side does not overlap with the vicinity of the tire radial outer end of the bead filler, a locally low rigidity part (bead filler) where no hard rubber is present from the bead portion to the tread portion. Between the radially outer end and the tire radially inner end of the reinforcing layer), and large distortion is generated in this portion, which is not preferable.
[0028]
Therefore, it is preferable that the reinforcing layer overlap a part in the tire radial direction inside with respect to the vicinity of the tire radial outer end of the bead filler, and it is preferable that the overlap dimension is at least 5 mm.
[0029]
According to a fourth aspect of the present invention, in the pneumatic tire according to any one of the first to third aspects, the reinforcing layer has a tire radially inner end located closer to a tire radially outer end of the bead core. Also located on the tire radial direction outer side, the tire radial direction outer end of the reinforcing layer is separated by at least 10 mm or more inward in the tire radial direction from the end of the rewinding portion in the tire width direction outermost, I have.
[0030]
Next, the operation of the pneumatic tire according to claim 4 will be described.
[0031]
If the distance between the outer end of the reinforcing layer in the tire radial direction and the end of the outermost rewinding portion in the tire width direction is less than 10 mm, the ends are too close to each other and easily become a failure nucleus due to distortion.
[0032]
When the tire rolls, the bead portion repeatedly falls outward in the tire direction and is repeatedly pressed by the rim flange.
[0033]
When the tire radial inner end of the reinforcing layer is positioned radially inward of the tire radial outer end of the bead core, when the bead falls down due to rolling of the tire, the bead is strongly pressed by the rim flange, and the bead is bent. The reinforcing layer inside the part is also strongly pressed.
[0034]
Since the rubber of the reinforcing layer is hard, cracks are liable to occur due to repeated strains caused by the pressing of the rim flange, and there is a possibility that separation occurs therefrom, which may lower the durability of the bead portion.
[0035]
Therefore, the reinforcing layer, the tire radial direction inner end is located outside the tire radial direction outer end of the bead core in the tire radial direction, the tire radial direction outer end from the end of the outermost rewinding portion in the tire width direction in the tire radial direction. It is preferable to be spaced at least 10 mm or more inward.
[0036]
According to a fifth aspect of the present invention, in the pneumatic tire according to any one of the first to fourth aspects, the reinforcing layer has a thickness in a range of 0.5 to 1.5 mm. It is characterized by.
[0037]
Next, the operation of the pneumatic tire according to claim 5 will be described.
[0038]
By setting the thickness of the reinforcing layer in the range of 0.5 to 1.5 mm, the bead portion can be sufficiently reinforced, and the volume of the bead filler can be sufficiently reduced accordingly.
[0039]
If the thickness of the reinforcing layer is less than 0.5 mm, the effect of reinforcing the bead portion is insufficient, and the volume of the bead filler cannot be sufficiently reduced.
[0040]
On the other hand, when the thickness of the reinforcing layer exceeds 1.5 mm, in the raw tire manufacturing process, when further attaching the side rubber on the reinforcing layer attached to the outer surface of the carcass ply, the end of the reinforcing layer, the carcass surface, In addition, a large space surrounded by the side rubber, that is, an air pocket is generated, which causes separation and the like.
[0041]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a pneumatic tire according to an embodiment of the present invention will be described with reference to the accompanying drawings.
[0042]
As shown in FIG. 1, the pneumatic tire 10 has a pair of bead cores 12 (only one side is shown in FIG. 1) and a carcass 14 that straddles the pair of bead cores 12 in a toroidal shape.
[0043]
In the present embodiment, the carcass 14 is composed of two carcass plies, a carcass ply 15 inside the tire and a carcass ply 16 outside the tire.
[0044]
The carcass plies 15, 16 are folded from the inside in the tire axial direction to the outside around the bead core 12 buried in the bead portion 17 near the width direction end.
[0045]
In addition, the end 15E of the carcass ply 15 is disposed at a position further away from the end 16E of the carcass ply 16 in the tire radial direction.
[0046]
In order to secure the rigidity of the bead portion 20, between the main body portion 16A of the carcass ply 16 that straddles the pair of bead cores 12 in a toroidal shape and the folded portion 16B of the carcass ply 16 that is folded outward. The bead filler 22 made of rubber having relatively high hardness (compared to the side rubber layer 24, the inner liner 34, and the tread rubber layer 42 described later) is provided.
[0047]
The height BH of the bead filler 22 is set within a range of 20% to 35% of the tire section height SH.
[0048]
A side rubber layer 24 is formed outside the carcass 14 in the tire axial direction.
[0049]
On the other hand, an inner liner 34 is provided inside the carcass 14 in the tire axial direction.
[0050]
A belt 40 including at least one belt ply 40A and 40B in the present embodiment is provided outside the carcass 14 in the tire radial direction.
[0051]
A reinforcing layer 41A and a reinforcing layer 41B are disposed outside the belt 40 in the tire radial direction, and a tread rubber layer 42 is further disposed outside the tire radial direction.
[0052]
On the outer side of the folded portion 15B of the carcass ply 15 in the tire width direction, a reinforcing layer 44 made of rubber having substantially the same hardness as the rubber constituting the bead filler 22 is provided on the outermost surface of the carcass 14 in the tire width direction. Is provided in close contact with the outer surface of the folded portion 15B.
[0053]
The hardness of the rubber forming the reinforcing layer 44 is preferably within ± 5 degrees with respect to the hardness of the rubber forming the bead filler 22.
[0054]
Further, the hardness of the rubber constituting the reinforcing layer 44 is preferably in the range of 90 to 100 degrees.
[0055]
The reinforcing layer 44 is preferably provided in a range from the tire radial inner end 12E of the bead core 12 to a position 60% of the tire sectional height SH.
[0056]
The reinforcing layer 44 extends outward in the tire radial direction from the tire radial outer end 22E of the bead filler 22 and extends the tire radial outer end 44EO to the end of the adjacent ply, in the present embodiment, the rewinding portion 15B of the carcass ply 15. It is preferable to be separated from the end 15E by at least 10 mm or more.
[0057]
In addition, the reinforcing layer 44 has a tire radial direction inner end 44EI disposed in the tire radial direction inner side of the tire radial direction outer end 22E of the bead filler 22 and a part of the tire radial direction inner side in the tire radial direction outer end of the bead filler 22. It is preferable to overlap around 22E.
[0058]
It is preferable that the tire radial inner end 44EI of the reinforcing layer 44 and the vicinity of the tire radial outer end 22E of the bead filler 22 overlap at least 5 mm.
[0059]
The thickness of the reinforcing layer 44 is preferably in the range of 0.5 to 1.5 mm.
(Action)
In the pneumatic tire 10 of the present embodiment, the height BH of the bead filler 22 is set in the range of 20 to 35% of the tire cross-section height SH to reduce the volume of the bead filler 22 as compared with the related art. The reduction in rigidity due to the reduction in the volume of the filler 22 is compensated for by the reinforcing layer 44, so that steering stability is ensured.
[0060]
The bead filler 22 is made of hard rubber, and deteriorates due to the use of the tire, and has a higher hardness. However, since the volume is reduced as compared with the related art, even if the hardness is increased, the noise and the ride performance are reduced. Can be reduced.
[0061]
The hardening due to the deterioration of the reinforcing layer 44 is small in the reinforcing layer 44 as compared with the bead filler 22 and has little effect on the bending rigidity. Stability, noise and riding comfort are well balanced.
[0062]
Therefore, according to the pneumatic tire 10 of the present embodiment, it is possible to simultaneously secure the steering stability, suppress the deterioration of the noise after use, and suppress the decrease in the riding comfort after use.
[0063]
Further, by setting the hardness of the rubber of the reinforcing layer 44 in the range of 90 to 100 degrees, it is possible to suppress noise after use and suppress a decrease in ride comfort and ensure steering stability at a high level.
[0064]
Here, when the height BH of the bead filler 22 is less than 20% of the tire cross-section height SH, the rigidity of the tire side region is insufficient, and the steering stability and durability cannot be sufficiently secured.
[0065]
On the other hand, if the height BH of the bead filler 22 exceeds 35% of the tire cross-section height SH, the rigidity of the tire side region becomes too high, and the original purpose of suppressing noise and reduction in ride comfort can be achieved. Disappears.
[0066]
If the hardness of the rubber of the reinforcing layer 44 is less than 90 degrees, it becomes difficult to secure the steering stability.
[0067]
On the other hand, when the hardness of the rubber of the reinforcing layer 44 exceeds 100 degrees, it is difficult to secure ride comfort.
[0068]
If the distance between the tire radial outer end 44EO of the reinforcing layer 44 and the end 15E of the rewinding portion 15B is less than 10 mm, the ends are too close to each other, and it becomes easy to become a failure nucleus due to distortion.
[0069]
On the other hand, when the tire radial inner end 44EI of the reinforcing layer 44 is located inside the tire radial direction outer end of the bead core 12 in the tire radial direction, the reinforcing layer 44 may be cracked and the durability of the bead portion 17 may be reduced. There is.
[0070]
If the thickness of the reinforcing layer 44 is less than 0.5 mm, the reinforcing effect of the bead portion 17 is insufficient, and the volume of the bead filler cannot be sufficiently reduced.
[0071]
On the other hand, when the thickness of the reinforcing layer 44 exceeds 1.5 mm, when the side rubber layer 24 is attached on the reinforcing layer 44 attached to the outer surface of the carcass 14 in the process of manufacturing a raw tire, as shown in FIG. In addition, a large space surrounded by the end portion of the reinforcing layer 44, the carcass surface, and the side rubber 24, that is, an air pool 46 is generated, which causes separation and the like.
(Test example)
In order to confirm the effects of the present invention, a pneumatic tire according to a conventional example, a tire according to an example according to the present invention, and a pneumatic tire according to a comparative example are prepared. And a test of steering stability.
[0072]
Hereinafter, pneumatic tires of a conventional example, a comparative example, and an example will be described.
[0073]
Example: As shown in FIG. 1, it has a reinforcing layer.
[0074]
Conventional example, Comparative example 1: As shown in FIG. 3, it has the same configuration as the example except that no reinforcing layer is provided.
[0075]
Comparative Examples 2 to 8: A reinforcing layer is provided, but the dimensions and rubber hardness of each part are different from those of the examples.
[0076]
In each case, the tire size is 205/65 R15.
Next, a test method will be described.
[0077]
The test was carried out by preparing a new test tire and a deteriorated test tire, respectively, and attaching them to a passenger car.
[0078]
The deteriorated product was made as follows.
[0079]
First, the tire was mounted on a rim and filled with oxygen. The internal pressure was set to 350 kPa, and left for one week in an environment of 60 ° C.
[0080]
Thereafter, oxygen was removed and air was filled. The internal pressure was set to 350 kPa, and left for 1 week in an environment of 80 ° C.
[0081]
Noise: Comprehensive judgment based on the measurement of in-vehicle sound by a sound level meter when traveling on asphalt road surface and sensory evaluation by evaluation panelists. This is a relative evaluation with the conventional product set to 100, and the larger the numerical value, the lower the noise.
[0082]
Ride comfort: Sensory evaluation test by evaluation panelists. This is a relative evaluation with the conventional product set to 100, and the larger the numerical value, the better the ride comfort.
[0083]
Driving stability: Sensory evaluation test by evaluation panelists. This is a relative evaluation with the conventional product set to 100, and the larger the numerical value, the better the steering stability.
[0084]
Tables 1 to 5 below show the specifications of the test tires and the test results.
[0085]
Further, the height of the upper end of the reinforcing layer and the height of the lower end of the reinforcing layer in the table are dimensions measured outward in the tire radial direction on the basis of the bead heel similarly to the tire sectional height.
[0086]
Further, the reinforcing layer range is a difference between the height of the upper end of the reinforcing layer and the height of the lower end of the reinforcing layer.
[0087]
[Table 1]

[0088]
[Table 2]

[0089]
[Table 3]

[0090]
[Table 4]

[0091]
[Table 5]

As shown in Tables 1 to 5, it can be seen that the tires of the examples to which the present invention is applied have smaller performance degradation after deterioration than the conventional examples and the comparative examples.
[0092]
【The invention's effect】
Since the pneumatic tire of the present invention is configured as described above, it has an excellent effect that it is possible to simultaneously secure steering stability, suppress noise after use, and suppress a decrease in ride comfort.
[Brief description of the drawings]
FIG. 1 is a sectional view of a pneumatic tire according to one embodiment of the present invention.
FIG. 2 is a cross-sectional view near an end of a reinforcing layer.
FIG. 3 is a cross-sectional view of a pneumatic tire according to a conventional example.
[Explanation of symbols]
Reference Signs List 10 Pneumatic tire 12 Bead core 15 Carcass ply 16 Carcass ply 17 Bead portion 22 Bead filler 44 Reinforcing layer

Claims (5)

At least one carcass ply that straddles between a pair of bead portions in a toroidal shape, and the vicinity of a width direction end portion is wrapped around the bead core arranged in the bead portion from the inside to the outside in the tire width direction,
The carcass ply is disposed between the main body portion of the carcass ply that straddles the pair of bead portions in a toroidal shape and the carcass ply rewinding portion wound around the bead core, and extends outward from the bead core in the tire radial direction. A bead filler set within a range of 20 to 35% of the height of the tire cross section,
The carcass ply is disposed on the outer side in the tire width direction from the rewinding portion, is made of rubber having a hardness substantially equal to the bead filler, and extends at least in the tire radial direction outside the tire radial direction outer end of the bead filler, And a reinforcing layer formed thinner than the bead filler. The pneumatic tire according to claim 1, wherein the hardness of the rubber of the reinforcing layer is in a range of 90 to 100 degrees. The reinforcing layer, near the tire radial inner end, overlaps with the tire radial outer end near the bead filler, near the tire radial inner end of the reinforcing layer and the tire radial outer end of the bead filler. The pneumatic tire according to claim 1 or 2, wherein an overlap dimension with the vicinity is set to at least 5 mm. 4. The tire radial outer end of the reinforcing layer is separated from the radially outermost end of the rewinding portion in the tire width direction by at least 10 mm or more inward in the tire radial direction, according to claim 1. The pneumatic tire according to any one of the preceding claims. The pneumatic tire according to any one of claims 1 to 4, wherein the reinforcing layer has a thickness in a range of 0.5 to 1.5 mm.

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