JP2011057183A - Pneumatic tire - Google Patents

Pneumatic tire Download PDF

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JP2011057183A
JP2011057183A JP2009212383A JP2009212383A JP2011057183A JP 2011057183 A JP2011057183 A JP 2011057183A JP 2009212383 A JP2009212383 A JP 2009212383A JP 2009212383 A JP2009212383 A JP 2009212383A JP 2011057183 A JP2011057183 A JP 2011057183A
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tire
rubber layer
tread
side region
belt
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Hiroshi Nakada
広 中田
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Bridgestone Corp
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Bridgestone Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein wear of rubber easily advances and lowering of wear resistance of a tire tread is not avoided since a shape holding effect becomes large during high and heavy load due to high rigidity of a peripheral direction belt, thereby the movement of the rubber itself of the tire tread is increased, and the problem wherein deterioration of wear balance between a tread center part and a tread shoulder part is generated. <P>SOLUTION: The pneumatic tire includes a belt layer 12 composed of at least one layer of a peripheral direction belt ply 15 and at least two layers of crossing belt plies 14, and the tread 13 composed of a cap rubber layer 17 and a base rubber layer 16. The cap rubber layer 17 has a larger elastic modulus than that of the base rubber layer 16. The base rubber layer 16 is formed so that a tire equatorial plane CL side region including a tire equatorial plane CL may be thinner than a tire shoulder part SH side region. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

この発明は、空気入りタイヤに関し、特に、周方向ベルトを採用している、トラック・バスに用いて好適な重荷重用の空気入りラジアルタイヤに関する。   The present invention relates to a pneumatic tire, and more particularly to a heavy-duty pneumatic radial tire that employs a circumferential belt and is suitable for use in trucks and buses.

従来、カーカスの外側にタイヤ周方向に沿って層状に装着された周方向ベルトを採用している、キャップ（ＣＡＰ）／ベース（ＢＡＳＥ）構造の重荷重用ラジアルタイヤ、例えば、超扁平のトラック・バス用ラジアルタイヤ等の空気入りタイヤが知られている。   Conventionally, a heavy-duty radial tire with a cap (CAP) / base (BASE) structure, for example, an ultra flat truck / bus, which employs a circumferential belt that is layered along the tire circumferential direction on the outside of the carcass A pneumatic tire such as a radial tire is known.

近年、大型トラック或いはバスにおいては、車両の低燃費化及び軽量化のためにタイヤのシングル装着構造を採用する例が多くなっており、このシングル装着構造に対応して、タイヤの低扁平率化及びトレッドベースの幅広化が進んでいる。一般に、低い扁平率の空気入りタイヤは、ベルト層を一対の交差ベルトプライと、周方向補強のための周方向ベルトプライにより構成しており、これにより、高い内圧負荷時においてタイヤ形状を保持し、また、車両走行時における耐遠心力性及び耐発熱性を向上させ、もって、タイヤ耐久性能の向上を図っている。   In recent years, in large trucks and buses, there are many examples of adopting a single tire mounting structure for reducing fuel consumption and weight of the vehicle, and corresponding to this single mounting structure, the tire has a low flatness ratio. And the tread base is becoming wider. In general, a pneumatic tire having a low flatness has a belt layer composed of a pair of cross belt plies and a circumferential belt ply for circumferential reinforcement, thereby maintaining the tire shape under a high internal pressure load. In addition, the anti-centrifugal force and the heat resistance during running of the vehicle are improved, thereby improving the tire durability performance.

なお、キャップ／ベース構造は、タイヤトレッドが、タイヤ半径方向外側に配置されたキャップゴム層とタイヤ半径方向内側に配置されたベースゴム層の２層構造を有するものである。
このような構造を備えた重荷重用ラジアルタイヤとして、例えば、「重荷重用ラジアルタイヤ」（特許文献１参照）がある。 The cap / base structure has a two-layer structure in which the tire tread includes a cap rubber layer disposed on the outer side in the tire radial direction and a base rubber layer disposed on the inner side in the tire radial direction.
As a radial tire for heavy loads having such a structure, for example, there is a “radial tire for heavy loads” (see Patent Document 1).

特開２００３−１２７６１３号公報JP 2003-127613 A

しかしながら、従来の、周方向ベルトを採用した重荷重用ラジアルタイヤにおいては、周方向ベルトが高剛性であるために荷重負荷時の形状保持効果が大きく、タイヤ回転時のタイヤ側面形状が正円に近くなる。そのため、タイヤ接地部分の接地長さが短くなるので、接地圧の上昇を招き、この接地圧の上昇により、タイヤトレッドのゴムが圧縮変形を受け易くなってゴムが大きく変形することになる。この結果、タイヤトレッドのゴム自体の動きが大きくなることからゴムの磨耗が進み易く、タイヤトレッドの耐磨耗性能の低下が避けられなかった。   However, in conventional heavy duty radial tires that use a circumferential belt, the circumferential belt is highly rigid, so the shape retention effect under load is great, and the tire side shape during tire rotation is close to a perfect circle. Become. For this reason, since the contact length of the tire contact portion is shortened, the contact pressure increases, and the increase in the contact pressure causes the rubber of the tire tread to be easily subjected to compressive deformation, and the rubber is greatly deformed. As a result, since the movement of the rubber of the tire tread itself becomes large, the wear of the rubber tends to proceed, and the wear resistance performance of the tire tread is inevitably lowered.

また、タイヤトレッドにおいてトレッド中心部の磨耗速度がトレッド肩部に比べて速いため、トレッド中心部とトレッド肩部の磨耗バランスの悪化も生じていた。
この発明の目的は、周方向ベルトを適用した構造にあって、タイヤトレッドにおける耐磨耗性能を高めると共に、トレッド中心部とトレッド肩部の磨耗バランスの悪化を防ぎ、磨耗寿命を延ばした空気入りタイヤを提供することである。 In addition, since the wear speed at the center of the tread in the tire tread is faster than that at the shoulder of the tread, the wear balance between the center of the tread and the shoulder of the tread has also deteriorated.
The object of the present invention is a pneumatic structure that has a structure to which a circumferential belt is applied, improves the wear resistance performance of the tire tread, prevents the wear balance of the tread center portion and the tread shoulder portion from deteriorating, and extends the wear life. Is to provide tires.

上記目的を達成するため、この発明に係る空気入りタイヤは、少なくとも１層の周方向ベルトプライ及び少なくとも２層の交差ベルトプライからなるベルト層と、キャップゴム層とベースゴム層からなるトレッドとを有しており、前記キャップゴム層は、前記ベースゴム層より弾性率が大きく、前記ベースゴム層は、タイヤ肩部側領域よりタイヤ赤道面を含むタイヤ赤道面側領域の方が厚みが薄く形成されている。   In order to achieve the above object, a pneumatic tire according to the present invention comprises a belt layer comprising at least one circumferential belt ply and at least two intersecting belt plies, and a tread comprising a cap rubber layer and a base rubber layer. The cap rubber layer has a larger elastic modulus than the base rubber layer, and the base rubber layer is formed to be thinner in the tire equatorial plane side region including the tire equatorial plane than in the tire shoulder side region. Has been.

また、この発明の他の態様に係る空気入りタイヤは、前記ベースゴム層を、前記タイヤ赤道面側領域の厚みが５ｍｍ以下で、前記タイヤ赤道面側領域と前記タイヤ肩部側領域の厚み差を３ｍｍ以上有するようにしている。
また、この発明の他の態様に係る空気入りタイヤは、前記タイヤ肩部側領域を、前記周方向溝によって区画される陸部において、タイヤ幅方向最外側に位置する肩側陸部の外側面から、前記肩側陸部の一列内側に位置する第１内側陸部のタイヤ幅方向中央までとしている。
また、この発明の他の態様に係る空気入りタイヤは、扁平率を６０％以下としている。 In the pneumatic tire according to another aspect of the present invention, the base rubber layer has a thickness difference of 5 mm or less in the tire equatorial plane side region, and a difference in thickness between the tire equatorial plane side region and the tire shoulder side region. 3 mm or more.
In the pneumatic tire according to another aspect of the present invention, the outer surface of the shoulder-side land portion located on the outermost side in the tire width direction in the land portion partitioned by the circumferential groove in the tire shoulder-side region. To the center in the tire width direction of the first inner land portion located on the inner side of the shoulder side land portion.
In the pneumatic tire according to another aspect of the present invention, the flatness is 60% or less.

この発明に係る空気入りタイヤによれば、キャップゴム層は、ベースゴム層より弾性率が大きく、ベースゴム層は、タイヤ肩部側領域よりタイヤ赤道面を含むタイヤ赤道面側領域の方が厚みが薄く形成されているので、周方向ベルトを適用した構造にあって、タイヤトレッドにおける耐磨耗性能を高めると共に、トレッド中心部とトレッド肩部の磨耗バランスの悪化を防ぎ、磨耗寿命を延ばすことができる。
また、この発明の他の態様に係る空気入りタイヤによれば、ベースゴム層を、タイヤ赤道面側領域の厚みが５ｍｍ以下で、タイヤ赤道面側領域とタイヤ肩部側領域の厚み差を３ｍｍ以上有するようにしているので、上記効果をより効果的に奏することができる。 According to the pneumatic tire of the present invention, the cap rubber layer has a larger elastic modulus than the base rubber layer, and the base rubber layer is thicker in the tire equatorial plane side region including the tire equatorial plane than in the tire shoulder side region. Since it is thinly formed, it has a structure with a circumferential belt applied to improve the wear resistance performance of the tire tread, prevent deterioration of the wear balance between the tread center and tread shoulder, and extend the wear life. Can do.
In the pneumatic tire according to another aspect of the present invention, the base rubber layer has a thickness of 5 mm or less in the tire equatorial plane side region, and a difference in thickness between the tire equatorial plane side region and the tire shoulder side region is 3 mm. Since it has made it above, the said effect can be show | played more effectively.

また、この発明の他の態様に係る空気入りタイヤによれば、タイヤ肩部側領域を、周方向溝によって区画される陸部において、タイヤ幅方向最外側に位置する肩側陸部の外側面から、肩側陸部の一列内側に位置する第１内側陸部のタイヤ幅方向中央までとしているので、上記効果をより効果的に奏することができる。
また、この発明の他の態様に係る空気入りタイヤによれば、扁平率を６０％以下としているので、上記効果をより効果的に奏することができる。 Moreover, according to the pneumatic tire which concerns on the other aspect of this invention, the outer side surface of the shoulder side land part located in a tire width direction outermost part in the land part divided by the circumferential groove | channel on the tire shoulder side area | region To the center in the tire width direction of the first inner land portion located inside the row on the shoulder side land portion, the above effect can be more effectively achieved.
Moreover, according to the pneumatic tire which concerns on the other aspect of this invention, since the flat rate is 60% or less, the said effect can be show | played more effectively.

この発明の一実施の形態に係る空気入りタイヤの構成を模式的に示すタイヤ幅方向に沿う断面図である。1 is a cross-sectional view along a tire width direction schematically showing a configuration of a pneumatic tire according to an embodiment of the present invention. 図１の空気入りタイヤにおけるタイヤ肩部領域を示し、（ａ）は周方向溝が３本の場合の概念説明図、（ｂ）は周方向溝が４本の場合の概念説明図、（ｃ）は周方向溝が５本の場合の概念説明図、（ｄ）は周方向溝が６本の場合の概念説明図である。1 shows a tire shoulder region in the pneumatic tire of FIG. 1, (a) is a conceptual explanatory diagram when there are three circumferential grooves, (b) is a conceptual explanatory diagram when there are four circumferential grooves, (c) ) Is a conceptual explanatory diagram when there are five circumferential grooves, and (d) is a conceptual explanatory diagram when there are six circumferential grooves.

以下、この発明を実施するための形態について図面を参照して説明する。
図１は、この発明の一実施の形態に係る空気入りタイヤの構成を模式的に示すタイヤ幅方向に沿う断面図である。図１に示すように、空気入りタイヤ１０は、タイヤの骨格を構成するカーカス層１１、カーカス層１１のタイヤ径方向外側に配置されるベルト層１２、及びベルト層１２のタイヤ径方向外側に配置されるトレッド１３を有しており、例えば、トラックバス用ラジアルタイヤ（Ｔｒｕｃｋ・Ｂｕｓ Ｒａｄｉａｌ Ｔｉｒｅ：ＴＢＲ）等の超扁平の重荷重用ラジアルタイヤである。 Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view along a tire width direction schematically showing a configuration of a pneumatic tire according to an embodiment of the present invention. As shown in FIG. 1, a pneumatic tire 10 includes a carcass layer 11 constituting a tire skeleton, a belt layer 12 disposed on the outer side in the tire radial direction of the carcass layer 11, and an outer side in the tire radial direction of the belt layer 12. For example, it is an ultra-flat radial heavy-duty tire such as a truck / bus radial tire (TBR).

カーカス層１１は、環状構造を有する左右一対のビードコア（図示しない）間に、トロイダル状に架け渡されている。
ベルト層１２は、少なくとも２層の交差ベルトプライ１４と、少なくとも１層の周方向ベルトプライ１５を有して積層されている。これらのベルトプライ１４，１５は、例えば、スチール繊維材或いは有機繊維材からなる複数のベルトコードを圧延加工することにより形成されている。 The carcass layer 11 is bridged in a toroidal shape between a pair of left and right bead cores (not shown) having an annular structure.
The belt layer 12 is laminated having at least two layers of cross belt plies 14 and at least one circumferential belt ply 15. These belt plies 14 and 15 are formed, for example, by rolling a plurality of belt cords made of steel fiber material or organic fiber material.

交差ベルトプライ１４は、ベルトコードの繊維方向をタイヤ周方向に対し所定のベルト角度を有して傾斜配置されており、ベルトコードの繊維方向をタイヤ周方向に対して相互に異なる方向に傾斜させて積層されている。また、周方向ベルトプライ１５は、ベルトコードの繊維方向がタイヤ周方向に対し略平行になるように配置されている。この周方向ベルトプライ１５は、波状に癖付けしたコードベルトやハイエロンゲーションベルトにより形成することが望ましい。   The cross belt ply 14 is arranged so that the fiber direction of the belt cord is inclined with a predetermined belt angle with respect to the tire circumferential direction, and the fiber direction of the belt cord is inclined in different directions with respect to the tire circumferential direction. Are stacked. The circumferential belt ply 15 is disposed so that the fiber direction of the belt cord is substantially parallel to the tire circumferential direction. The circumferential belt ply 15 is preferably formed of a cord belt or a high elongation belt that is brazed in a wave shape.

トレッド１３は、タイヤ半径方向内側に配置されたベース（ＢＡＳＥ）ゴム層１６と、タイヤ半径方向外側に配置されたキャップ（ＣＡＰ）ゴム層１７との２層構造を有しており、キャップゴム層１７によりタイヤ踏面が形成される。このキャップゴム層１７には、タイヤ周方向に延びる周方向溝１３ａが３本以上形成されている。トレッド１３に続くカーカス層１１のタイヤ幅方向外側には、タイヤのサイドウォール部１８を形成するサイドウォールゴムが配置されている。   The tread 13 has a two-layer structure of a base (BASE) rubber layer 16 disposed on the inner side in the tire radial direction and a cap (CAP) rubber layer 17 disposed on the outer side in the tire radial direction. A tire tread is formed by 17. The cap rubber layer 17 has three or more circumferential grooves 13a extending in the tire circumferential direction. Sidewall rubber that forms the sidewall portion 18 of the tire is disposed on the outer side in the tire width direction of the carcass layer 11 following the tread 13.

ベースゴム層１６とキャップゴム層１７は、その弾性率が異なっており、キャップゴム層１７の弾性率の方がベースゴム層１６の弾性率より大きく（ＣＡＰ弾性率＞ＢＡＳＥ弾性率）なるように形成されている。また、ベースゴム層１６は、タイヤ肩部ＳＨ側領域の厚み（ゲージ）より、タイヤ赤道面ＣＬが通るトレッド１３中央部、即ち、タイヤ赤道面ＣＬを含むタイヤ赤道面ＣＬ側領域の厚み（ゲージ）の方が薄く（ＣＬゲージ＜ＳＨゲージ）形成されている（図１参照）。   The base rubber layer 16 and the cap rubber layer 17 have different elastic moduli, and the elastic modulus of the cap rubber layer 17 is larger than that of the base rubber layer 16 (CAP elastic modulus> BASE elastic modulus). Is formed. Further, the base rubber layer 16 has a thickness (gauge) of the tire equatorial plane CL side region including the tire equatorial plane CL, that is, the central portion of the tread 13 through which the tire equatorial plane CL passes, based on the thickness (gauge) of the tire shoulder SH side area. ) Is thinner (CL gauge <SH gauge) (see FIG. 1).

更に、タイヤ赤道面ＣＬを含むタイヤ赤道面ＣＬ側領域のベースゴム層１６の厚みは５ｍｍ以下とし、タイヤ赤道面ＣＬ側領域とタイヤ肩部ＳＨ側領域の厚みの差（ゲージ差）は３ｍｍ以上あることが望ましい。
ここで、タイヤ肩部ＳＨ側領域Ｓについて説明する。
図２は、図１の空気入りタイヤにおけるタイヤ肩部領域を示し、（ａ）は周方向溝が３本の場合の概念説明図、（ｂ）は周方向溝が４本の場合の概念説明図、（ｃ）は周方向溝が５本の場合の概念説明図、（ｄ）は周方向溝が６本の場合の概念説明図である。 Further, the thickness of the base rubber layer 16 in the tire equatorial plane CL side region including the tire equatorial plane CL is 5 mm or less, and the difference in thickness (gauge difference) between the tire equatorial plane CL side region and the tire shoulder SH side region is 3 mm or more. It is desirable to be.
Here, the tire shoulder SH side region S will be described.
FIG. 2 shows a tire shoulder region in the pneumatic tire of FIG. 1, (a) is a conceptual explanatory diagram when there are three circumferential grooves, and (b) is a conceptual description when there are four circumferential grooves. FIG. 4C is a conceptual explanatory diagram when there are five circumferential grooves, and FIG. 4D is a conceptual explanatory diagram when there are six circumferential grooves.

図２に示すように、タイヤ肩部ＳＨ側領域Ｓは、周方向溝１３ａによって区画される陸部において、タイヤ幅方向最外側に位置する陸部であるＳＨ（肩側）陸部１９ａの外側面から、ＳＨ陸部１９ａの一列内側に位置する第１内側陸部１９ｂのタイヤ幅方向中央まで（即ち、ＳＨ陸部１９ａの全領域＋第１内側陸部１９ｂの５０％領域）とする。
また、空気入りタイヤ１０の扁平率は６０％以下とすることが望ましい。 As shown in FIG. 2, the tire shoulder SH side region S is outside the SH (shoulder side) land portion 19 a that is a land portion located on the outermost side in the tire width direction in the land portion defined by the circumferential groove 13 a. From the side surface to the center in the tire width direction of the first inner land portion 19b located on the inner side of the SH land portion 19a (that is, the entire region of the SH land portion 19a + the 50% region of the first inner land portion 19b).
Further, the flatness of the pneumatic tire 10 is desirably 60% or less.

次に、上記構成を有する空気入りタイヤ１０におけるゴムの変形について説明する。
周方向ベルトを採用している重荷重用ラジアルタイヤにおける、トレッドの耐磨耗性能の低下及びトレッドの中心と肩部の磨耗バランスの悪化は、周方向ベルトを適用したことによるトレッドゴムの変形の増加がもたらしたものである。
このトレッドゴムの変形はゴムの弾性率に比例することから、変形の大きい部分を硬くすれば変形の増加を生じさせないことが、研究の結果より明らかになり、特に、荷重負荷時のタイヤ形状保持効果、即ち、荷重負荷時にタイヤ側面形状が略真円形状に保持される効果が大きい、タイヤ赤道面ＣＬが通るトレッドのタイヤ幅方向中心、即ち、トレッド中心部の弾性率を大きくすれば良いことが判明した。 Next, deformation of rubber in the pneumatic tire 10 having the above configuration will be described.
Deterioration of the tread wear resistance and deterioration of the tread center and shoulder wear balance in heavy duty radial tires using a circumferential belt are due to increased tread rubber deformation due to the application of the circumferential belt. Is the result of
Since the deformation of this tread rubber is proportional to the elastic modulus of the rubber, it has become clear from research results that the hard deformation of the tread rubber does not cause an increase in deformation. The effect, that is, the effect that the tire side surface shape is maintained in a substantially circular shape when a load is applied is large. There was found.

しかしながら、キャップゴム層のゴムの硬度を高めてゴムを硬くすることは、ゴムの変形を抑制することになるものの、トレッドゴムの剛性が上がり過ぎて、トレッドパターンのブロック、即ち、陸部がもげ易い等の不具合を招く。これらの不具合を招くことなく効率的に弾性率を上げるには、タイヤ赤道面ＣＬが通るトレッド中心部のベースゴム層の厚みを薄くすれば良い。
これは、一般的に、ベースゴム層のゴムは、発熱性を良くすることを目的として軟らかく設定してあるためであり、軟らかいベースゴム層の厚みを薄くして軟らかいゴムの量を減らすことで、タイヤ赤道面ＣＬが通るトレッド中心部の弾性率を大きくすることができる。 However, increasing the hardness of the rubber of the cap rubber layer to harden the rubber suppresses the deformation of the rubber, but the rigidity of the tread rubber is excessively increased, and the tread pattern block, that is, the land portion is peeled off. Inconveniences such as easy. In order to efficiently increase the elastic modulus without incurring these problems, the thickness of the base rubber layer at the center of the tread through which the tire equatorial plane CL passes may be reduced.
This is because the rubber of the base rubber layer is generally set soft for the purpose of improving the heat build-up, and by reducing the amount of soft rubber by reducing the thickness of the soft base rubber layer. The elastic modulus at the center of the tread through which the tire equatorial plane CL passes can be increased.

一方、トレッドにおけるゴムの発熱性は、ゴムの厚みが厚くなるタイヤ肩部ＳＨで殆ど決まってしまうが、当該部分は、発熱性のために配置しているベースゴム層のゴムの厚みを薄くすることが困難であると共に、タイヤ肩部ＳＨは、元々形状保持効果が大きくないため、タイヤ赤道面ＣＬが通るトレッド中心部のような現象は発生し難い。
よって、タイヤ赤道面ＣＬが通るトレッド中心部とタイヤ肩部ＳＨ部の磨耗バランスを考慮すれば、タイヤ肩部ＳＨ部のベースゴム層の厚みを変更する必要性は小さい。 On the other hand, the exothermic property of the rubber in the tread is almost determined by the tire shoulder SH where the thickness of the rubber becomes thick, but this portion reduces the thickness of the rubber of the base rubber layer disposed for the exothermic property. In addition, since the shape retaining effect of the tire shoulder SH is not originally large, a phenomenon such as a tread center portion through which the tire equatorial plane CL passes is unlikely to occur.
Therefore, considering the wear balance between the tread center portion through which the tire equatorial plane CL passes and the tire shoulder portion SH, there is little need to change the thickness of the base rubber layer of the tire shoulder portion SH.

このことから、キャップゴム層１７のゴムを硬くすることなく、ベースゴム層１６のゴムの厚みを、タイヤ赤道面ＣＬが通るトレッド中心部、即ち、タイヤ赤道面ＣＬを含むタイヤ赤道面ＣＬ側領域と、タイヤ肩部ＳＨ側領域とで異ならせることにより、周方向ベルト１５を適用している扁平のトラックバス用ラジアルタイヤにおいて、タイヤの耐磨耗性能を向上させ磨耗寿命を長くすることができる。   From this, the rubber thickness of the base rubber layer 16 is set to the tread center portion through which the tire equatorial plane CL passes, that is, the tire equatorial plane CL side region including the tire equatorial plane CL without hardening the rubber of the cap rubber layer 17. In the flat truck bus radial tire to which the circumferential belt 15 is applied, the wear resistance of the tire can be improved and the wear life can be extended. .

この発明に係る空気入りタイヤ１０を三種類（発明例１〜３）試作し、耐磨耗性能等について二種類の従来例（従来例１，２）との比較試験を行った。
試作したのは、タイヤサイズが４９５／４５Ｒ２２５で、交差ベルト１４と周方向ベルト１５をそれぞれ２層ずつ設けた超扁平の重荷重用ラジアルタイヤであり、以下の緒元を有する。 Three types of pneumatic tires 10 according to the present invention (Invention Examples 1 to 3) were prototyped and subjected to a comparative test with two types of conventional examples (Conventional Examples 1 and 2) in terms of wear resistance and the like.
The prototype was an ultra-flat radial heavy-duty tire with a tire size of 495 / 45R225 and two layers each of the cross belt 14 and the circumferential belt 15 and has the following specifications.

周方向溝本数：発明例と従来例の何れも６本
タイヤ赤道面ＣＬが通るトレッド中心部のベースゴム層１６のゴム厚（ＣＬ ＢＡＳＥ Ｇａ．）：従来例１，２は１０ｍｍ、発明例１，２は５ｍｍ、発明例３は０ｍｍ
タイヤ肩部ＳＨのベースゴム層１６のゴム厚（ＳＨ ＢＡＳＥ Ｇａ．）：従来例１，２と発明例１〜３の何れも１０ｍｍ
交差ベルト２の幅：従来例１が２２０ｍｍ、従来例２が３８０ｍｍ、発明例１が２２０ｍｍ、発明例２，３が３８０ｍｍ
交差ベルト１の幅：従来例１，２と発明例１〜３の何れも４２０ｍｍ
周方向ベルト２の幅：従来例１，２と発明例１〜３の何れも３７０ｍｍ
周方向ベルト１の幅：従来例１，２と発明例１〜３の何れも３７０ｍｍ Number of circumferential grooves: 6 in both the invention example and the conventional example Rubber thickness of the base rubber layer 16 in the center of the tread through which the tire equatorial plane CL passes (CL BASE Ga.): 10 mm in the conventional examples 1 and 2, and the invention example 1 , 2 is 5 mm, Invention Example 3 is 0 mm
Rubber thickness of the base rubber layer 16 of the tire shoulder SH (SH BASE Ga.): 10 mm for each of Conventional Examples 1 and 2 and Invention Examples 1 to 3
Cross belt 2 width: 220 mm for Conventional Example 1, 380 mm for Conventional Example 2, 220 mm for Invention Example 1, 380 mm for Invention Examples 2 and 3
Cross belt 1 width: 420 mm for Conventional Examples 1 and 2 and Invention Examples 1 to 3
The width of the circumferential belt 2: 370 mm in the conventional examples 1 and 2 and the invention examples 1 to 3
The width of the circumferential belt 1: 370 mm in the conventional examples 1 and 2 and the invention examples 1 to 3

Figure 2011057183
Figure 2011057183

試作した上記サイズのタイヤを１７．００インチ幅の適用リムに組み込み、内圧９００ｋｐａで、トラクターヘッドのドライブ軸に装着し、定積載のトレーラーを引いて５００００ｋｍ走行したときの、タイヤ赤道面ＣＬが通るトレッド中心部及びタイヤ肩部ＳＨにおける周方向溝の深さを測定した。測定結果を以下に示す。   The prototype tire of the above size is assembled in a 17.00 inch wide applicable rim, mounted on the drive shaft of the tractor head at an internal pressure of 900 kpa, and the tire equatorial plane CL passes when the fixed trailer is pulled and travels 50000 km. The depth of the circumferential groove in the tread center and the tire shoulder SH was measured. The measurement results are shown below.

ここで、適用リムとは、ＪＡＴＭＡ（The Japan Automobile Tyre Manufacturers Association,Inc.）に規定される「適用リム」、ＴＲＡ（THE TIRE AND RIM ASSOCIATION INC.）に規定される「Design Rim」、或いはＥＴＲＴＯ（THE European Tyre and Rim Technical Organisation）に規定される「Measuring Rim」をいう。また、正規内圧とは、ＪＡＴＭＡに規定される「最高空気圧」、ＴＲＡに規定される「TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES」の最大値、或いはＥＴＲＴＯに規定される「INFLATION PRESSURES」をいう。また、規定荷重とは、ＪＡＴＭＡに規定される「最大負荷能力」、ＴＲＡに規定される「TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES」の最大値、或いはＥＴＲＴＯに規定される「LOAD CAPACITY」をいう。   Here, the applicable rim is an “applied rim” defined by JATMA (The Japan Automobile Tire Manufacturers Association, Inc.), a TRA (Design Rim) defined by THE TIRE AND RIM ASSOCIATION INC., Or ETRTO. “Measuring Rim” as defined in (THE European Tire and Rim Technical Organization). The normal internal pressure means “maximum air pressure” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The specified load means “maximum load capacity” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO.

磨耗した周方向溝の深さ（新品時の周方向溝の深さ−走行後の周方向溝の深さ）を比較した結果を以下に示す。
タイヤ赤道面ＣＬが通るトレッド中心部の磨耗した周方向溝の深さ（ＣＬ磨耗溝深さ）：従来例１は１０．３ｍｍ、従来例２は９．７ｍｍ、発明例１は５．２ｍｍ、発明例２は４．９ｍｍ、発明例３は４．１ｍｍ
タイヤ肩部ＳＨの磨耗した周方向溝の深さ（ＳＨ磨耗溝深さ）：従来例１は３．４ｍｍ、従来例２は３．３ｍｍ、発明例１は３．５ｍｍ、発明例２は３．１ｍｍ、発明例３は３．３ｍｍ The result of comparing the depth of the worn circumferential groove (the depth of the circumferential groove when a new article−the depth of the circumferential groove after traveling) is shown below.
Depth of circumferential groove worn at the center of the tread through which the tire equatorial plane CL passes (CL wear groove depth): Conventional Example 1 is 10.3 mm, Conventional Example 2 is 9.7 mm, Invention Example 1 is 5.2 mm, Invention Example 2 is 4.9 mm, Invention Example 3 is 4.1 mm
Depth of worn circumferential groove of tire shoulder SH (SH wear groove depth): Conventional example 1 is 3.4 mm, Conventional example 2 is 3.3 mm, Invention example 1 is 3.5 mm, Invention example 2 is 3 0.1 mm, Invention Example 3 is 3.3 mm

Figure 2011057183
Figure 2011057183

上記結果から分かるように、タイヤ赤道面ＣＬが通るトレッド中心部の磨耗した周方向溝１３の深さ、即ち、新品時の周方向溝１３ａの深さから走行後の周方向溝１３ａの深さを引いた値は、従来例１が１０．３ｍｍ、従来例２が９．７ｍｍと、何れも略１０ｍｍも磨耗していたのに対し、発明例１は５．２ｍｍ、発明例２は４．９ｍｍ、発明例３は４．１ｍｍと、平均約４．７３ｍｍ、最大でも５．２ｍｍであり、従来例に比べ略半減していた。   As can be seen from the above results, the depth of the worn circumferential groove 13 at the center of the tread through which the tire equatorial plane CL passes, that is, the depth of the circumferential groove 13a after traveling from the depth of the circumferential groove 13a when new is used. The values obtained by subtracting 10 were 10.3 mm for Conventional Example 1 and 9.7 mm for Conventional Example 2, both of which were about 10 mm, while those of Invention Example 1 were 5.2 mm and Invention Example 2 was 4. 9 mm, Invention Example 3 was 4.1 mm, an average of about 4.73 mm, and a maximum of 5.2 mm, which was substantially halved compared to the conventional example.

この発明によれば、キャップゴム層は、ベースゴム層より弾性率が大きく、ベースゴム層は、タイヤ肩部側領域よりタイヤ赤道面を含むタイヤ赤道面側領域の方が厚みが薄く形成されていることから、周方向ベルトを適用した構造にあって、タイヤトレッドにおける耐磨耗性能を高めると共に、トレッド中心部とトレッド肩部の磨耗バランスの悪化を防ぎ、磨耗寿命を延ばすことができるので、空気入りタイヤ、特に、周方向ベルトを採用している、トラック・バスに用いて好適な重荷重用の空気入りラジアルタイヤに最適である。   According to this invention, the cap rubber layer has a larger elastic modulus than the base rubber layer, and the base rubber layer is formed such that the tire equatorial plane side region including the tire equatorial plane is thinner than the tire shoulder side region. Because it has a structure that applies a circumferential belt, it can improve the wear resistance performance of the tire tread, prevent deterioration of the wear balance between the tread center and the tread shoulder, and extend the wear life. It is most suitable for pneumatic tires, particularly pneumatic radial tires for heavy loads suitable for trucks and buses, which employ circumferential belts.

１０ 空気入りタイヤ
１１ カーカス層
１２ ベルト層
１３ トレッド
１３ａ 周方向溝
１４ 交差ベルトプライ
１５ 周方向ベルトプライ
１６ ベースゴム層
１７ キャップゴム層
１８ サイドウォール部
１９ａ ＳＨ陸部
１９ｂ 第１内側陸部
ＣＬ タイヤ赤道面
ＳＨ タイヤ肩部
Ｓ タイヤ肩部ＳＨ側領域 DESCRIPTION OF SYMBOLS 10 Pneumatic tire 11 Carcass layer 12 Belt layer 13 Tread 13a Circumferential groove 14 Cross belt ply 15 Circumferential belt ply 16 Base rubber layer 17 Cap rubber layer 18 Side wall part 19a SH land part 19b First inner land part CL Tire equator Surface SH Tire shoulder S Tire shoulder SH side area

Claims (4)

少なくとも１層の周方向ベルトプライ及び少なくとも２層の交差ベルトプライからなるベルト層と、
キャップゴム層とベースゴム層からなるトレッドとを有し、
前記キャップゴム層は、前記ベースゴム層より弾性率が大きく、前記ベースゴム層は、タイヤ肩部側領域よりタイヤ赤道面を含むタイヤ赤道面側領域の方が厚みが薄く形成された空気入りタイヤ。 A belt layer comprising at least one circumferential belt ply and at least two cross belt plies;
It has a tread consisting of a cap rubber layer and a base rubber layer,
The cap rubber layer has a larger elastic modulus than the base rubber layer, and the base rubber layer has a tire equator plane side region including a tire equator side region formed thinner than a tire shoulder side region. . 前記ベースゴム層は、
前記タイヤ赤道面側領域の厚みが５ｍｍ以下で、前記タイヤ赤道面側領域と前記タイヤ肩部側領域の厚み差を３ｍｍ以上有する請求項１に記載の空気入りタイヤ。 The base rubber layer is
The pneumatic tire according to claim 1, wherein the tire equatorial plane side region has a thickness of 5 mm or less, and has a thickness difference of 3 mm or more between the tire equatorial plane side region and the tire shoulder side region. 前記タイヤ肩部側領域は、
前記周方向溝によって区画される陸部において、タイヤ幅方向最外側に位置する肩側陸部の外側面から、前記肩側陸部の一列内側に位置する第１内側陸部のタイヤ幅方向中央までとする請求項１または２に記載の空気入りタイヤ。 The tire shoulder side region is
In the land portion defined by the circumferential groove, the center in the tire width direction of the first inner land portion located on the inner side of the shoulder side land portion from the outer surface of the shoulder side land portion located on the outermost side in the tire width direction. The pneumatic tire according to claim 1 or 2, wherein 扁平率が６０％以下である請求項１から３のいずれか一項に記載の空気入りタイヤ。   The pneumatic tire according to any one of claims 1 to 3, wherein the flatness is 60% or less.
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012218496A (en) * 2011-04-05 2012-11-12 Yokohama Rubber Co Ltd:The Pneumatic tire
CN103935189A (en) * 2014-04-14 2014-07-23 江苏通用科技股份有限公司 Tire tread extrusion-molding structure applicable to mixed road conditions
US9045004B2 (en) 2011-09-22 2015-06-02 The Yokohama Rubber Co., Ltd. Pneumatic tire
KR101869194B1 (en) * 2017-04-28 2018-06-19 한국타이어 주식회사 Tire comprising muti layer tread
KR101869195B1 (en) * 2017-04-28 2018-06-19 한국타이어 주식회사 Tire comprising muti layer tread

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012218496A (en) * 2011-04-05 2012-11-12 Yokohama Rubber Co Ltd:The Pneumatic tire
US9045004B2 (en) 2011-09-22 2015-06-02 The Yokohama Rubber Co., Ltd. Pneumatic tire
DE112011105656B4 (en) * 2011-09-22 2016-02-18 The Yokohama Rubber Co., Ltd. tire
CN103935189A (en) * 2014-04-14 2014-07-23 江苏通用科技股份有限公司 Tire tread extrusion-molding structure applicable to mixed road conditions
KR101869194B1 (en) * 2017-04-28 2018-06-19 한국타이어 주식회사 Tire comprising muti layer tread
KR101869195B1 (en) * 2017-04-28 2018-06-19 한국타이어 주식회사 Tire comprising muti layer tread

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