JP2007015451A - Pneumatic tire - Google Patents

Pneumatic tire Download PDF

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JP2007015451A
JP2007015451A JP2005196559A JP2005196559A JP2007015451A JP 2007015451 A JP2007015451 A JP 2007015451A JP 2005196559 A JP2005196559 A JP 2005196559A JP 2005196559 A JP2005196559 A JP 2005196559A JP 2007015451 A JP2007015451 A JP 2007015451A
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tire
bead
carcass
ply
rubber layer
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JP4738918B2 (en
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Takamichi Sagawa
敬道 佐川
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Sumitomo Rubber Industries Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To enhance the trend of getting over a projection by enhancing the shock absorbing performance without impairing the maneuvering stability. <P>SOLUTION: A pneumatic tire is furnished in its bead part 4 with a retaining surface S1 extending in contact with the tire cavity side inner surface of a ply body part 6a of carcass 6, and the retaining surface S1 is furnished with a reinforcing rubber layer 10 approximately in a crescent shape curving in an arc of circle having center on the tire cavity side. When the tire is in the regular internal pressure condition, the ply body part 6a lies alongside the retaining surface S1 and curves smoothly in a circular arc having the center on the tire cavity side in the region Y of 90% or more of the range from the carcass maximum width point Pm to the segregation starting point Pe from the bead core 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、ビード部に補強ゴム層を設けてカーカスプロファイルを適正化することにより、乗り心地性を向上させた空気入りタイヤに関する。   The present invention relates to a pneumatic tire in which riding comfort is improved by providing a reinforcing rubber layer in a bead portion to optimize a carcass profile.

図４（Ａ）に示すように、空気入りタイヤの骨格をなすカーカスプライａは、ビードコアｂ、ｂ間を跨るプライ本体部ａ１の両端を、該ビードコアｂの廻りでタイヤ軸方向内から外に折り返すことにより係止されるとともに、前記プライ本体部ａ１と折返し部ａ２との間には、ビード補強用のビードエーペックスゴムｃが配されている。   As shown in FIG. 4 (A), the carcass ply a constituting the skeleton of the pneumatic tire has both ends of the ply main body a1 straddling between the bead cores b and b extending from inside the tire axial direction around the bead core b. A bead apex rubber c for bead reinforcement is disposed between the ply main body portion a1 and the folded portion a2.

そして、タイヤに正規内圧を充填した正規内圧状態において、前記プライ本体部ａ１は、ビードコアｂからタイヤ半径方向外側かつタイヤ軸方向外側に向かって、いったんタイヤ外側に中心を有する凹円弧状に湾曲し、しかる後タイヤ内腔側に中心を有する凸円弧状に湾曲しながらトレッドまで延在している。即ちビード側の逆Ｒの凹円弧領域ｙ１と、トレッド側の凸円弧領域ｙ２とからなる凹凸のカーカスプロファイルを有する。   In the normal internal pressure state in which the tire is filled with the normal internal pressure, the ply body a1 is once bent into a concave arc shape having a center on the tire outer side from the bead core b toward the tire radial direction outer side and the tire axial direction outer side. Thereafter, it extends to the tread while curving into a convex arc shape having a center on the tire lumen side. That is, it has a concave and convex carcass profile composed of a reverse-arc concave arc region y1 on the bead side and a convex arc region y2 on the tread side.

このようなカーカスプロファイルでは、タイヤがたわみ変形する凸円弧領域ｙ２が少ないため、突起乗越し時の反力が大きく、ショック吸収性に劣るなど乗り心地性に問題がある。なお図４（Ｂ）に示す如く、ビードエーペックスゴムｃを小型化し、凸円弧領域ｙ２の占める割合を高めることも提案されている。しかし斯かる場合には、タイヤ剛性が不充分となりハンドル応答性が減じるとともに、振動の収束性が損なわれ、ブルブル感となってタイヤに揺れが発生する傾向となる。   In such a carcass profile, since the convex arc region y2 in which the tire bends and deforms is small, there is a problem in ride comfort such as a large reaction force when riding over the protrusion and poor shock absorption. As shown in FIG. 4B, it has been proposed to reduce the size of the bead apex rubber c and increase the proportion of the convex arc region y2. However, in such a case, the tire rigidity becomes insufficient and the steering wheel response decreases, and the convergence of vibration is impaired.

そこで本発明は、ビード部かつカーカスのプライ本体部の内側に、タイヤ内腔側に中心を有する凸円弧状をなし前記プライ本体部の内面を保持する保持面を有する補強ゴム層を設けることを基本として、ハンドル応答性や振動の収束性を損ねることなく、ショック吸収性（突起乗り越し性）を高めることができ、操縦安定性を維持しながら乗り心地性を向上しうる空気入りタイヤを提供することを目的としている。   Therefore, the present invention provides a reinforcing rubber layer having a convex arc shape having a center on the tire lumen side inside the bead portion and the carcass ply main body portion and having a holding surface for holding the inner surface of the ply main body portion. Basically, a pneumatic tire that can improve shock absorption (protrusion overriding) without impairing steering response and vibration convergence, and can improve riding comfort while maintaining steering stability is provided. The purpose is that.

特開平３−１９３５１０号公報Japanese Patent Laid-Open No. 3-193510

前記目的を達成するために、本願請求項１の発明は、トレッド部からサイドウォール部をへてビード部のビードコアに至るプライ本体部に、前記ビードコアの廻りをタイヤ軸方向内側から外側に折り返されるプライ折返し部を一連に設けたカーカスプライからなるカーカスと、前記ビードコアからタイヤ半径方向外方にのびるビードエーペックスゴムとを具えた空気入りタイヤであって、
前記ビード部に、前記プライ本体部のタイヤ内腔側内面に接してのびる保持面を有しかつ該保持面がタイヤ内腔側に中心を有する円弧状に湾曲する略三日月状の補強ゴム層を設けるとともに、
タイヤを正規リムに装着しかつ正規内圧を充填した無負荷の正規内圧状態において、前記プライ本体部は、前記保持面に沿いかつ該プライ本体部がタイヤ軸方向外側に最も突出するカーカス最大巾点から、プライ本体部がビードコアから離間を開始する離間開始点までの範囲の９０％以上の領域Ｙで、タイヤ内腔側に中心を有する円弧状に滑らかに湾曲することを特徴としている。 In order to achieve the above object, the invention of claim 1 of the present application is folded around the bead core from the inner side to the outer side in the tire axial direction by a ply body part extending from the tread part through the sidewall part to the bead core of the bead part. A pneumatic tire comprising a carcass made of a carcass ply provided with a series of ply turn-up portions, and a bead apex rubber extending outward in the tire radial direction from the bead core,
The bead portion has a substantially crescent-shaped reinforcing rubber layer having a holding surface extending in contact with the inner surface of the tire lumen side of the ply main body portion and curved in an arc shape having the center on the tire lumen side. While providing
The carcass maximum width point at which the ply main body portion extends along the holding surface and the ply main body portion protrudes most outward in the tire axial direction in a no-load normal internal pressure state in which a tire is mounted on a normal rim and filled with a normal internal pressure. From the bead core, the ply main body is smoothly curved in an arc shape having a center on the tire lumen side in a region Y that is 90% or more of the range from the bead core to the separation start point.

又請求項２の発明では、前記補強ゴム層は、ゴム硬度が８０〜１００°の硬質のゴムからなることを特徴としている。
又請求項３の発明では、前記補強ゴム層は、そのタイヤ半径方向外端のビードベースラインからの半径方向高さＨ１を、前記ビードエーペックスゴムのタイヤ半径方向外端のビードベースラインからの半径方向高さＨ２より大、かつ前記カーカス最大巾点のビードベースラインからの半径方向高さＨ３より小としたことを特徴としている。
又請求項４の発明では、前記補強ゴム層は、その最大厚さＴmax を１．０〜１５．０ｍｍとしたことを特徴としている。 According to a second aspect of the present invention, the reinforcing rubber layer is made of a hard rubber having a rubber hardness of 80 to 100 °.
In the invention of claim 3, the reinforcing rubber layer has a radial height H1 from the bead base line at the outer end in the tire radial direction, and a radius from the bead base line at the outer end in the tire radial direction of the bead apex rubber. It is characterized by being larger than the directional height H2 and smaller than the radial height H3 from the bead base line of the carcass maximum width point.
According to a fourth aspect of the present invention, the reinforcing rubber layer has a maximum thickness Tmax of 1.0 to 15.0 mm.

本明細書では、ゴム硬度は、温度２５℃の雰囲気下で測定したるデュロメータータイプＡによる硬さである。又前記「正規リム」とは、タイヤが基づいている規格を含む規格体系において、当該規格がタイヤ毎に定めるリムであり、例えばＪＡＴＭＡであれば標準リム、ＴＲＡであれば "Design Rim" 、或いはＥＴＲＴＯであれば "Measuring Rim"を意味する。また前記「正規内圧」とは、前記規格がタイヤ毎に定めている空気圧であり、ＪＡＴＭＡであれば最高空気圧、ＴＲＡであれば表 "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" に記載の最大値、ＥＴＲＴＯであれば "INFLATION PRESSURE" を意味するが、乗用車用タイヤの場合には１８０ｋＰａとする。なお特に断りがない限り、タイヤの各部の寸法等は、前記正規内圧状態で特定される値とする。   In the present specification, the rubber hardness is a hardness according to a durometer type A measured in an atmosphere at a temperature of 25 ° C. The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based, for example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO means "Measuring Rim". The “regular internal pressure” is the air pressure determined by the standard for each tire. The maximum air pressure for JATMA, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” for TRA, In the case of ETRTO, it means “INFLATION PRESSURE”, but in the case of passenger tires, it is 180 kPa. Unless otherwise specified, the dimensions and the like of each part of the tire are values specified in the normal internal pressure state.

本発明は叙上の如く、ビード部かつカーカスのプライ本体部の内側に、タイヤ内腔側に中心を有する凸円弧状をなしかつ前記プライ本体部の内面に接する保持面を有する略三日月状の補強ゴム層を設け、これにより、カーカス最大巾点と、ビードコア離間開始点との間の範囲の９０％以上の領域Ｙにおいてカーカスプロファイルを、タイヤ内腔側に中心を有する滑らかな円弧としている。従って、タイヤのたわみ変形域を十分確保でき、突起乗越し時の反力を抑え、ショック吸収性を向上しうる。又前記補強ゴム層の形成によってタイヤ剛性が確保されるため、ハンドル応答性等の操縦安定性の低下、及び振動収束性等の低下をそれぞれ抑制することができる。   As described above, the present invention has a substantially crescent-like shape having a convex arc shape having a center on the tire lumen side inside the bead portion and the carcass ply main body portion and having a holding surface in contact with the inner surface of the ply main body portion. By providing a reinforcing rubber layer, the carcass profile is a smooth arc having a center on the tire lumen side in a region Y of 90% or more of the range between the carcass maximum width point and the bead core separation start point. Accordingly, a sufficient deflection deformation region of the tire can be ensured, a reaction force when riding over the protrusion can be suppressed, and shock absorption can be improved. Moreover, since the tire rigidity is ensured by the formation of the reinforcing rubber layer, it is possible to suppress a decrease in steering stability such as steering response and a decrease in vibration convergence.

以下、本発明の実施の一形態を、図示例とともに説明する。
図１は本発明の空気入りタイヤの正規内圧状態を示す断面図、図２はそのビード部を拡大して示す断面図である。
図１に示すように、空気入りタイヤ１は、トレッド部２からサイドウォール部３をへてビード部４のビードコア５に至るカーカス６と、前記ビードコア５からタイヤ半径方向外方にのびるビードエーペックスゴム８と、ビード部４かつ前記カーカス６のタイヤ内腔側に配される略三日月状の補強ゴム層１０とを具える。又カーカス６の半径方向外側かつトレッド部２の内部には、トレッド補強用の強靱なベルト層７が配される。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a normal internal pressure state of the pneumatic tire of the present invention, and FIG. 2 is an enlarged cross-sectional view showing a bead portion thereof.
As shown in FIG. 1, a pneumatic tire 1 includes a carcass 6 extending from a tread portion 2 through a sidewall portion 3 to a bead core 5 of a bead portion 4, and a bead apex rubber extending from the bead core 5 outward in the tire radial direction. 8 and a bead portion 4 and a substantially crescent-shaped reinforcing rubber layer 10 disposed on the tire lumen side of the carcass 6. Further, a tough belt layer 7 for reinforcing the tread is disposed outside the carcass 6 in the radial direction and inside the tread portion 2.

前記ベルト層７は、スチールコード等の高強力のベルトコードをタイヤ周方向に対して例えば１０〜３５゜程度で配列した２枚以上、本例では２枚のベルトプライ７Ａ、７Ｂから形成される。このベルト層７は、各ベルトコードがプライ間相互で交差することによりベルト剛性を高め、トレッド部２の略全巾をタガ効果を有して強固に補強する。本例では、ベルト層７の半径方向外側には、高速耐久性を高める目的で、例えばナイロン等の有機繊維のバンドコードを周方向に対して５度以下の角度で螺旋巻きしたバンド層９が配される。バンド層９としては、前記ベルト層７のタイヤ軸方向外端部のみを被覆する左右一対のエッジバンドプライ、及びベルト層７の略全巾を覆うフルバンドプライが適宜使用でき、本例では、１枚のフルバンドプライからなるものを例示している。   The belt layer 7 is formed of two or more belt plies 7A and 7B in this example, in which high-strength belt cords such as steel cords are arranged at, for example, about 10 to 35 ° with respect to the tire circumferential direction. . The belt layer 7 increases belt rigidity by crossing the belt cords between the plies, and reinforces substantially the entire width of the tread portion 2 with a tagging effect. In this example, on the radially outer side of the belt layer 7, for the purpose of enhancing high-speed durability, for example, a band layer 9 in which a band cord of an organic fiber such as nylon is spirally wound at an angle of 5 degrees or less with respect to the circumferential direction. Arranged. As the band layer 9, a pair of left and right edge band plies that covers only the outer end portion in the tire axial direction of the belt layer 7 and a full band ply that covers substantially the entire width of the belt layer 7 can be used as appropriate. An example of one full band ply is shown.

又前記カーカス６は、カーカスコードをタイヤ周方向に対して７５゜〜９０゜の角度で配列した１枚以上、本例では１枚のカーカスプライ６Ａから形成される。カーカスコードとしては、ナイロン、ポリエステル、レーヨン、芳香族ポリアミド等の有機繊維コードが好適に採用される。又カーカスプライ６Ａは、ビードコア５，５間を跨るプライ本体部６ａの両側に、該ビードコア５の周りをタイヤ軸方向内側から外側に折り返して係止されるプライ折返し部６ｂを一連に具える。   The carcass 6 is formed of one or more carcass plies 6A in this example, in which carcass cords are arranged at an angle of 75 ° to 90 ° with respect to the tire circumferential direction. As the carcass cord, an organic fiber cord such as nylon, polyester, rayon, aromatic polyamide or the like is preferably used. In addition, the carcass ply 6A includes a series of ply turn-up portions 6b that are folded and locked around the bead core 5 from the inner side to the outer side in the tire axial direction on both sides of the ply main body portion 6a straddling the bead cores 5 and 5.

そしてビード部４には、図２に示すように、このプライ本体部６ａとプライ折返し部６ｂとの間を通り、前記ビードコア５から半径方向外側にのびるビードエーペックスゴム８が配されるとともに、前記プライ本体部６ａのタイヤ内腔側には、補強ゴム層１０が配される。   As shown in FIG. 2, the bead portion 4 is provided with a bead apex rubber 8 that passes between the ply main body portion 6 a and the ply folded portion 6 b and extends radially outward from the bead core 5. A reinforcing rubber layer 10 is disposed on the tire lumen side of the ply body 6a.

前記補強ゴム層１０は、ゴム硬度Ｈｓ１が８０〜１００°の硬質のゴムからなり、厚肉の中央部１０Ａから、それぞれ半径方向内方及び外方に向かって厚さを漸減させてのびる略三日月状断面を有する。又補強ゴム層１０のタイヤ軸方向外側面Ｓｏは、前記プライ本体部６ａのタイヤ内腔側内面に接して該プライ本体部６ａを保持する保持面Ｓ１をなし、しかもこの保持面Ｓ１はタイヤ内腔側に中心を有する凸円弧状に湾曲している。   The reinforcing rubber layer 10 is made of a hard rubber having a rubber hardness Hs1 of 80 to 100 °, and has a substantially crescent moon extending gradually from the thick central portion 10A toward the inside and outside in the radial direction. Having a cross-section. Further, the outer surface So of the reinforcing rubber layer 10 in the tire axial direction is in contact with the inner surface of the ply main body 6a on the tire lumen side to form a holding surface S1 for holding the ply main body 6a. It is curved in a convex arc shape having a center on the cavity side.

ここで、補強ゴム層１０のタイヤ半径方向外端のビードベースラインＢＬからの半径方向高さＨ１は、前記ビードエーペックスゴム８のタイヤ半径方向外端のビードベースラインＢＬからの半径方向高さＨ２よりも大、かつ該プライ本体部６ａがタイヤ軸方向外側に最も突出するカーカス最大巾点ＰｍのビードベースラインＢＬからの半径方向高さＨ３よりも小に設定するのが好ましい。このとき前記補強ゴム層１０は、前記中央部１０Ａに最大厚さＴmax を有し、かつその最大厚さＴmax を、１．０〜１５．０ｍｍの範囲に設定している。   Here, the radial height H1 from the bead base line BL at the outer end in the tire radial direction of the reinforcing rubber layer 10 is the radial height H2 from the bead base line BL at the outer end in the tire radial direction of the bead apex rubber 8. And the ply main body 6a is preferably set to be smaller than the radial height H3 from the bead base line BL of the carcass maximum width point Pm at which the ply main body portion 6a protrudes most outward in the tire axial direction. At this time, the reinforcing rubber layer 10 has a maximum thickness Tmax at the central portion 10A, and the maximum thickness Tmax is set in a range of 1.0 to 15.0 mm.

又補強ゴム層１０のタイヤ半径方向外端、及び内端は、この補強ゴム層１０のタイヤ軸方向内側面Ｓｉ（タイヤ内腔側内面）が、前記プライ本体部６ａのタイヤ内腔側内面と滑らかに繋がるように、直径０．５ｍｍ以下の小円弧、或いはシャープなエッジ状に形成される。   Further, the outer end and the inner end of the reinforcing rubber layer 10 in the tire radial direction are the inner surface Si in the tire axial direction of the reinforcing rubber layer 10 (the inner surface on the tire lumen side) and the inner surface on the tire lumen side of the ply main body portion 6a. In order to connect smoothly, it is formed in a small circular arc with a diameter of 0.5 mm or less, or a sharp edge shape.

なお補強ゴム層１０のタイヤ軸方向内側面Ｓｉは、特に規制されることがなく、例えばタイヤ内腔側に中心を有する凸円弧状、或いは本例の如く略直線状に形成することもできる。又図３に示すように、タイヤ外側に中心を有する凹円弧状に形成することもできる。   Note that the inner side surface Si of the reinforcing rubber layer 10 in the tire axial direction is not particularly restricted, and can be formed, for example, in a convex arc shape having a center on the tire lumen side, or in a substantially linear shape as in this example. Moreover, as shown in FIG. 3, it can also form in the concave arc shape which has a center on the tire outer side.

又前記ビードエーペックスゴム８は、前記ビードコア５から半径方向外側に先細状にのびる断面略三角形状をなし、その外端の前記半径方向高さＨ２は、前記カーカス最大巾点Ｐｍの半径方向高さＨ３の０．１〜０．５倍の範囲と低く設定されている。なおビードエーペックスゴム８も、ゴム硬度Ｈｓ２が７０〜１００°の硬質のゴムから形成され、前記補強ゴム層１０と協働して、ビード部４からサイドウォール部３にかけて補強し、タイヤ横剛性を確保して、ハンドル応答性を含む操縦安定性を高く維持する。   The bead apex rubber 8 has a substantially triangular cross section extending radially outward from the bead core 5, and the radial height H2 of the outer end thereof is the radial height of the carcass maximum width point Pm. It is set as low as 0.1 to 0.5 times H3. The bead apex rubber 8 is also formed of a hard rubber having a rubber hardness Hs2 of 70 to 100 °, and is reinforced from the bead portion 4 to the sidewall portion 3 in cooperation with the reinforcing rubber layer 10 to increase the lateral stiffness of the tire. To ensure high handling stability including steering response.

そして本実施形態のタイヤ１では、前記補強ゴム層１０の凸円弧状の保持面Ｓ１に、カーカス６のプライ本体部６ａが保持される。これにより、前記正規内圧状態において、前記プライ本体部６ａは、前記カーカス最大巾点Ｐｍから、離間開始点Ｐｅまでの範囲の９０％以上の領域Ｙにおけるカーカスプロファイルを、タイヤ内腔側に中心を有して滑らかに湾曲する凸円弧形状ｚＬで構成している。即ちカーカス最大巾点Ｐｍよりも半径方向内側のカーカスプロファイルにおいて凸円弧形状ｚＬとなる凸円弧プロファイル域の半径方向長さＬａを、前記カーカス最大巾点Ｐｍから離間開始点Ｐｅまでの半径方向長さＬ０の９０％以上（本例では１００％）としている。なお前記「離間開始点Ｐｅ」とは、プライ本体部６ａがビードコア５から離間を開始する点を意味する。   In the tire 1 of the present embodiment, the ply main body portion 6a of the carcass 6 is held on the convex arc-shaped holding surface S1 of the reinforcing rubber layer 10. Thereby, in the normal internal pressure state, the ply main body portion 6a has the carcass profile in the region Y that is 90% or more of the range from the carcass maximum width point Pm to the separation start point Pe centered on the tire lumen side. It has a convex arc shape zL that is smoothly curved. That is, the radial direction length La of the convex arc profile region having the convex arc shape zL in the carcass profile radially inward from the carcass maximum width point Pm is set to the radial direction length from the carcass maximum width point Pm to the separation start point Pe. It is 90% or more of L0 (100% in this example). The “separation start point Pe” means a point at which the ply body 6 a starts to be separated from the bead core 5.

前記凸円弧形状ｚＬは、単一の曲率半径からなる円弧、もしくは複数の曲率半径を組み合わせた複合円弧であっても良い。又カーカスプロファイルは、当然ではあるが、前記カーカス最大巾点Ｐｍよりも半径方向外側の領域においてもタイヤ内腔側に中心を有する凸円弧形状ｚＵで構成され、この凸円弧形状ｚＵと前記凸円弧形状ｚＬとは、滑らかに連続している。   The convex arc shape zL may be an arc formed of a single curvature radius or a composite arc combining a plurality of curvature radii. Of course, the carcass profile is composed of a convex arcuate shape zU having a center on the tire lumen side in a region radially outward from the carcass maximum width point Pm. The convex arcuate shape zU and the convex arc The shape zL is smoothly continuous.

このように、カーカス最大巾点Ｐｍからビードコア離間開始点Ｐｅまでの範囲の９０％以上、好ましくは９５％、さらに好ましくは１００％の領域Ｙにおいて、プライ本体部６ａが、凸円弧形状ｚＬのプロファイルを有する。即ち、Ｌａ／Ｌ０を９０％以上、好ましくは９５％以上、さらに好ましくは１００％としているため、タイヤのたわみ変形域を十分に確保することが可能となる。従って、突起乗越し時の衝撃を分散でき、その反力を低く抑えうるなどショック吸収性を向上することができる。又前記補強ゴム層１０の形成によってタイヤ剛性、特にタイヤ横剛性が確保されるため、ハンドル応答性を含む操縦安定性を高く維持することができる。しかもタイヤ剛性の適度のアップにより、前記たわみ変形域の増加による振動収束性の低下を抑制することができ、ブルブル感、フワフワ感といったタイヤの揺れを防止することが可能となる。   Thus, in the region Y of 90% or more, preferably 95%, more preferably 100% of the range from the carcass maximum width point Pm to the bead core separation start point Pe, the ply body portion 6a has a profile with a convex arc shape zL. Have That is, since La / L0 is 90% or more, preferably 95% or more, and more preferably 100%, it is possible to secure a sufficient deflection deformation region of the tire. Therefore, shock absorption can be improved, such as being able to disperse the impact when riding over the protrusion and keeping the reaction force low. Further, the formation of the reinforcing rubber layer 10 ensures tire rigidity, particularly tire lateral rigidity, so that steering stability including steering response can be maintained high. In addition, by appropriately increasing the tire rigidity, it is possible to suppress a decrease in vibration convergence due to an increase in the deflection deformation region, and it is possible to prevent tire shaking such as a bull feeling and a fluffy feeling.

なお前記補強ゴム層１０のゴム硬度Ｈｓ１が８０°より小では、補強効果が不充分となって操縦安定性の低下を招くとともに、未加流状態での粘弾性に劣り、加流成型時のカーカスプライ６Ａへの押し付け力が不足して、前記凸円弧形状ｚＬのプロファイルをうることが難しくなる。逆に、ゴム硬度Ｈｓ１が１００°を超えると、補強ゴム層１０がカーカスプライ６Ａから剥離傾向となるなど、新たな損傷の恐れを招く。   When the rubber hardness Hs1 of the reinforced rubber layer 10 is less than 80 °, the reinforcing effect is insufficient and the steering stability is deteriorated, and the viscoelasticity in an unloaded state is inferior. The pressing force on the carcass ply 6A is insufficient, and it becomes difficult to obtain the profile of the convex arc shape zL. Conversely, if the rubber hardness Hs1 exceeds 100 °, the reinforcing rubber layer 10 tends to peel from the carcass ply 6A, which may cause new damage.

又補強ゴム層１０の最大厚さＴmax が１．０ｍｍより小、及び半径方向高さＨ１がビードエーペックスゴム８の半径方向高さＨ２以下の場合には、補強効果が不充分となって操縦安定性の低下を招く。逆に、最大厚さＴmax が１５．０ｍｍより大では、ビード部４のボリュウムが過大となって、不必要な重量増加を招くほか、内部発熱が高まりビード耐久性を低下させる。又前記半径方向高さＨ１がビードエーペックスゴム８の半径方向高さＨ２以上では、補強ゴム層１０の外端に応力が集中して損傷を起こす傾向となる。   Further, when the maximum thickness Tmax of the reinforcing rubber layer 10 is smaller than 1.0 mm and the radial height H1 is equal to or less than the radial height H2 of the bead apex rubber 8, the reinforcing effect is insufficient and the steering is stabilized. It causes a decline in sex. On the other hand, if the maximum thickness Tmax is greater than 15.0 mm, the volume of the bead portion 4 becomes excessive, leading to an unnecessary increase in weight, increasing internal heat generation and reducing bead durability. If the radial height H1 is equal to or higher than the radial height H2 of the bead apex rubber 8, the stress tends to concentrate on the outer end of the reinforcing rubber layer 10 to cause damage.

なお本例では、前記カーカス６のプライ折返し部６ｂの外端のビードベースラインＢＬからの半径方向高さＨ４は、前記補強ゴム層１０の半径方向高さＨ１より大であることが、ビードエーペックスゴム８の外端及び補強ゴム層１０の外端での剛性変化を円滑化し応力集中を抑制する上で好ましい。   In this example, the bead apex is that the radial height H4 from the bead base line BL of the outer end of the ply turn-up portion 6b of the carcass 6 is larger than the radial height H1 of the reinforcing rubber layer 10. This is preferable for smoothing the change in rigidity at the outer end of the rubber 8 and the outer end of the reinforcing rubber layer 10 and suppressing stress concentration.

以上、本発明の特に好ましい実施形態について詳述したが、本発明は図示の実施形態に限定されることなく、種々の態様に変形して実施しうる。   As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

図１の構造をなすタイヤサイズが１９５／６５Ｒ１５の空気入りタイヤを表１の仕様に基づき試作するとともに、各試供タイヤの突起乗り越し性、及び操縦安定性をテストした。   A pneumatic tire having a tire size of 195 / 65R15 having the structure shown in FIG. 1 was made on the basis of the specifications shown in Table 1 and tested for protrusion overriding and handling stability of each sample tire.

（１）突起乗り越し性：
供試タイヤをリム（１５×５．５Ｊ）、内圧（２３０ｋＰａ）の条件下で、ミニバン（排気量２０００ｃｃ、ＦＦ車）の全輪に装着し、タイヤ１本当たり４．３６ｋＮの荷重のもとに６０km／Ｈの速度で路上に設置した１０mm×１０mmの角材をのりこえたときの、衝撃をドライバーの官能評価により比較例１を３とする５点法で表示している。数値の大きい方が良好である。 (1) Overhang of protrusion:
The test tire is mounted on all wheels of a minivan (2000 cc displacement, FF car) under the conditions of a rim (15 x 5.5 J) and internal pressure (230 kPa), under a load of 4.36 kN per tire. In addition, the impact when a 10 mm × 10 mm square member installed on the road at a speed of 60 km / H is added is indicated by a five-point method in which Comparative Example 1 is set to 3 by sensory evaluation of the driver. A larger value is better.

（２）操縦安定性：
前記車両を用い、ドライアスファルト路のタイヤテストコースを走行し、ハンドル応答性、剛性感、グリップ等に関する特性をドライバーの官能評価により比較例１を１００とする指数で表示している。指数の大きい方が良好である。 (2) Steering stability:
The vehicle is run on a tire test course on a dry asphalt road, and characteristics relating to steering wheel response, rigidity, grip, and the like are indicated by an index with Comparative Example 1 being 100 by sensory evaluation of the driver. A larger index is better.

Figure 2007015451
Figure 2007015451

表１の如く実施例のタイヤは、操縦安定性を損ねることなく、ショック吸収性を高め突起乗越し性を向上しうるのが確認できる。   As shown in Table 1, it can be confirmed that the tires of the examples can improve the shock absorption and the protrusion overriding property without impairing the steering stability.

本発明の空気入りタイヤの一実施例を示す断面図である。It is sectional drawing which shows one Example of the pneumatic tire of this invention. そのビード部を拡大して示す断面図である。It is sectional drawing which expands and shows the bead part. 補強ゴム層の他の例を示す断面図である。It is sectional drawing which shows the other example of a reinforced rubber layer. （Ａ）は従来タイヤのカーカスプロファイルの一例を示す断面図、（Ｂ）は、他の例を示す断面図である。(A) is sectional drawing which shows an example of the carcass profile of a conventional tire, (B) is sectional drawing which shows another example.

符号の説明Explanation of symbols

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
１０ 補強ゴム層
ＢＬ ビードベースライン
Ｐｍ カーカス最大巾点
Ｐｅ 離間開始点
Ｓ１ 保持面 2 Tread portion 3 Side wall portion 4 Bead portion 5 Bead core 6 Carcass 6A Carcass ply 6a Ply main body portion 6b Ply folded portion 8 Bead apex rubber 10 Reinforced rubber layer BL Bead base line Pm Maximum width of carcass Pe Separation start point S1 Holding surface

Claims (4)

トレッド部からサイドウォール部をへてビード部のビードコアに至るプライ本体部に、前記ビードコアの廻りをタイヤ軸方向内側から外側に折り返されるプライ折返し部を一連に設けたカーカスプライからなるカーカスと、前記ビードコアからタイヤ半径方向外方にのびるビードエーペックスゴムとを具えた空気入りタイヤであって、
前記ビード部に、前記プライ本体部のタイヤ内腔側内面に接してのびる保持面を有しかつ該保持面がタイヤ内腔側に中心を有する円弧状に湾曲する略三日月状の補強ゴム層を設けるとともに、
タイヤを正規リムに装着しかつ正規内圧を充填した無負荷の正規内圧状態において、前記プライ本体部は、前記保持面に沿いかつ該プライ本体部がタイヤ軸方向外側に最も突出するカーカス最大巾点から、プライ本体部がビードコアから離間を開始する離間開始点までの範囲の９０％以上の領域Ｙで、タイヤ内腔側に中心を有する円弧状に滑らかに湾曲することを特徴とする空気入りタイヤ。 A carcass composed of a carcass ply provided with a series of ply turn-up portions that are turned from the inner side to the outer side in the tire axial direction around the bead core in the ply body portion extending from the tread portion to the bead core through the sidewall portion; A pneumatic tire comprising a bead apex rubber extending radially outward from the bead core,
The bead portion has a substantially crescent-shaped reinforcing rubber layer having a holding surface extending in contact with the inner surface of the tire lumen side of the ply main body portion and curved in an arc shape having the center on the tire lumen side. While providing
The carcass maximum width point at which the ply main body portion extends along the holding surface and the ply main body portion protrudes most outward in the tire axial direction in a no-load normal internal pressure state in which a tire is mounted on a normal rim and filled with a normal internal pressure. To 90% or more of the range Y from the bead core to the separation start point where separation starts from the bead core, and the pneumatic tire is smoothly curved into an arc having a center on the tire lumen side . 前記補強ゴム層は、ゴム硬度が８０〜１００°の硬質のゴムからなることを特徴とする請求項１記載の空気入りタイヤ。   The pneumatic tire according to claim 1, wherein the reinforcing rubber layer is made of hard rubber having a rubber hardness of 80 to 100 °. 前記補強ゴム層は、そのタイヤ半径方向外端のビードベースラインからの半径方向高さＨ１を、前記ビードエーペックスゴムのタイヤ半径方向外端のビードベースラインからの半径方向高さＨ２より大、かつ前記カーカス最大巾点のビードベースラインからの半径方向高さＨ３より小としたことを特徴とする請求項１又は２記載の空気入りタイヤ。   The reinforcing rubber layer has a radial height H1 from the bead base line at the outer end in the tire radial direction of the tire greater than a radial height H2 from the bead base line at the outer end in the tire radial direction of the bead apex rubber, and 3. The pneumatic tire according to claim 1, wherein the pneumatic tire is smaller than a radial height H <b> 3 from a bead base line of the carcass maximum width point. 前記補強ゴム層は、その最大厚さＴmax を１．０〜１５．０ｍｍとしたことを特徴とする請求項１〜３記載の何れか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 reinforcing rubber layer has a maximum thickness Tmax of 1.0 to 15.0 mm.
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110253282A1 (en) * 2008-12-22 2011-10-20 Michelin Recherche et Technique S.A. a corporation Sidewall shear decoupling layer
JP2011245992A (en) * 2010-05-27 2011-12-08 Yokohama Rubber Co Ltd:The Pneumatic tire
JP2011255858A (en) * 2010-06-11 2011-12-22 Yokohama Rubber Co Ltd:The Pneumatic tire and method for manufacturing the same
JP2012061920A (en) * 2010-09-15 2012-03-29 Bridgestone Corp Pneumatic tire
DE102013100364B4 (en) * 2012-01-17 2016-05-25 Toyo Tire & Rubber Co., Ltd. tire
CN110116589A (en) * 2018-02-06 2019-08-13 住友橡胶工业株式会社 Motorcycle tire

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Publication number Priority date Publication date Assignee Title
JPS62152909A (en) * 1985-12-27 1987-07-07 Yokohama Rubber Co Ltd:The Pneumatic tyre
JP2001191724A (en) * 2000-01-14 2001-07-17 Bridgestone Corp Pneumatic tire excellent in bead part durability
JP2002264615A (en) * 2001-03-09 2002-09-18 Bridgestone Corp Radial tire for heavy load

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62152909A (en) * 1985-12-27 1987-07-07 Yokohama Rubber Co Ltd:The Pneumatic tyre
JP2001191724A (en) * 2000-01-14 2001-07-17 Bridgestone Corp Pneumatic tire excellent in bead part durability
JP2002264615A (en) * 2001-03-09 2002-09-18 Bridgestone Corp Radial tire for heavy load

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110253282A1 (en) * 2008-12-22 2011-10-20 Michelin Recherche et Technique S.A. a corporation Sidewall shear decoupling layer
JP2011245992A (en) * 2010-05-27 2011-12-08 Yokohama Rubber Co Ltd:The Pneumatic tire
JP2011255858A (en) * 2010-06-11 2011-12-22 Yokohama Rubber Co Ltd:The Pneumatic tire and method for manufacturing the same
JP2012061920A (en) * 2010-09-15 2012-03-29 Bridgestone Corp Pneumatic tire
DE102013100364B4 (en) * 2012-01-17 2016-05-25 Toyo Tire & Rubber Co., Ltd. tire
CN110116589A (en) * 2018-02-06 2019-08-13 住友橡胶工业株式会社 Motorcycle tire

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