JP2017109526A - Pneumatic tire - Google Patents

Pneumatic tire Download PDF

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JP2017109526A
JP2017109526A JP2015243337A JP2015243337A JP2017109526A JP 2017109526 A JP2017109526 A JP 2017109526A JP 2015243337 A JP2015243337 A JP 2015243337A JP 2015243337 A JP2015243337 A JP 2015243337A JP 2017109526 A JP2017109526 A JP 2017109526A
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side wall
wall surface
land portion
inclination angle
tire
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JP6667281B2 (en
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由彦 橋本
Yoshihiko Hashimoto
由彦 橋本
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Toyo Tire Corp
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Toyo Tire and Rubber Co Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire in which an inclination angle is different between a side wall surface at one side of a land part and a side wall surface at the other side thereof, in which ununiformity in grounding pressure distributions of the land part is eliminated.SOLUTION: In a pneumatic tire which has at a tread part a land part 32 sandwiched between two main grooves 23 and 24 extending in a tire circumference direction, where an inclination angle relative to a normal direction of a reference profile line L of the land part 32 is different between a side wall surface 41 at one side and a side wall surface 42 at the other side of the land part 32, the land part 32 entirely protrudes outward in a tire radial direction than the reference profile line L, and a peak 44 of the protrusion is at the side wall surface 42 side smaller in an inclination angle than a center 46 in a width direction of the land part 32.SELECTED DRAWING: Figure 2

Description

本発明は、空気入りタイヤに関する。   The present invention relates to a pneumatic tire.

トレッド部にタイヤ周方向に延びる複数の主溝が設けられ、2本の主溝に挟まれた陸部を有する空気入りタイヤが知られている。この空気入りタイヤにおいて、特許文献1〜3に記載されているように、陸部を従来のものよりもタイヤ径方向外側へ突出させることが提案されている。その突出の頂点の位置は、特許文献1ではタイヤ幅方向の中心側にあり、特許文献2では車両装着時の内側にあり、特許文献3では陸部のエッジ部にある。   A pneumatic tire having a land portion that is provided with a plurality of main grooves extending in the tire circumferential direction in a tread portion and sandwiched between two main grooves is known. In this pneumatic tire, as described in Patent Documents 1 to 3, it is proposed that the land portion protrudes outward in the tire radial direction from the conventional one. The position of the apex of the protrusion is on the center side in the tire width direction in Patent Document 1, on the inner side when the vehicle is mounted in Patent Document 2, and on the edge portion of the land portion in Patent Document 3.

特開2013−189121号公報JP 2013-189121 A 特開2005−263180号公報JP 2005-263180 A 特開2010−12978号公報JP 2010-12978 A

ところで、2本の主溝に挟まれた陸部の一方側の側壁面と他方側の側壁面とで、陸部の基準プロファイル線の法線方向に対する傾斜角が異なる空気入りタイヤが存在する。この空気入りタイヤが接地すると、陸部のうち前記傾斜角が大きい方のエッジ部付近の接地圧が他方のエッジ部付近の接地圧よりも高くなり、陸部の接地圧分布が不均一になることが知られている。陸部の接地圧分布が不均一になると、操縦安定性や転がり抵抗に悪影響が出る。   By the way, there is a pneumatic tire in which the inclination angle with respect to the normal direction of the reference profile line of the land portion is different between the one side wall surface and the other side wall surface of the land portion sandwiched between the two main grooves. When this pneumatic tire comes into contact with the ground, the contact pressure near the edge portion having the larger inclination angle in the land portion becomes higher than the contact pressure near the other edge portion, and the contact pressure distribution in the land portion becomes uneven. It is known. If the ground pressure distribution in the land becomes uneven, the handling stability and rolling resistance will be adversely affected.

そこで本発明は、陸部の一方側の側壁面と他方側の側壁面とで、陸部の基準プロファイル線の法線方向に対する傾斜角が異なる空気入りタイヤであって、陸部の接地圧分布の不均一性が解消されたものを提供することを課題とする。   Accordingly, the present invention provides a pneumatic tire in which the inclination angle with respect to the normal direction of the reference profile line of the land portion is different between the one side wall surface and the other side wall surface of the land portion. It is an object of the present invention to provide a product in which the non-uniformity is eliminated.

本実施形態の空気入りタイヤは、トレッド部にタイヤ周方向に延びる2本の主溝に挟まれた陸部を有し、前記陸部の一方側の側壁面と他方側の側壁面とで、前記陸部の基準プロファイル線の法線方向に対する傾斜角が異なる空気入りタイヤにおいて、前記陸部全体が前記陸部の基準プロファイル線よりタイヤ径方向外側へ突出し、その突出の頂点が、前記陸部の幅方向の中心位置よりも、前記傾斜角が小さい方の側壁面側にあることを特徴とする。   The pneumatic tire of the present embodiment has a land portion sandwiched between two main grooves extending in the tire circumferential direction in the tread portion, and a side wall surface on one side and a side wall surface on the other side of the land portion, In a pneumatic tire having different inclination angles with respect to the normal direction of the reference profile line of the land portion, the entire land portion protrudes outward in the tire radial direction from the reference profile line of the land portion, and the top of the protrusion is the land portion. It is characterized by being on the side of the side wall surface having the smaller inclination angle than the center position in the width direction.

本実施形態の空気入りタイヤでは、一方側の側壁面と他方側の側壁面とで傾斜角が異なる陸部が基準プロファイル線よりタイヤ径方向外側へ突出し、その突出の頂点が傾斜角の小さい方の側壁面側にあることにより、接地圧分布の不均一性が解消されている。   In the pneumatic tire of the present embodiment, land portions having different inclination angles on one side wall surface and the other side wall surface protrude outward in the tire radial direction from the reference profile line, and the top of the protrusion has a smaller inclination angle. Therefore, the non-uniformity of the ground pressure distribution is eliminated.

本実施形態の空気入りタイヤ10の幅方向断面図。1 is a cross-sectional view in the width direction of a pneumatic tire 10 of the present embodiment. メディエイト陸部32の幅方向断面図。The width direction sectional view of the mediate land portion 32. (a)比較例1のメディエイト陸部132の幅方向断面図。(b)比較例2のメディエイト陸部232の幅方向断面図。(A) The width direction sectional view of the mediate land part 132 of comparative example 1. FIG. (B) The width direction sectional view of mediate land part 232 of comparative example 2.

本実施形態の空気入りタイヤ10について図面に基づき説明する。なお図面は説明のために誇張されて描かれる場合がある。   The pneumatic tire 10 of this embodiment is demonstrated based on drawing. The drawings may be exaggerated for the purpose of explanation.

図1に示す本実施形態の空気入りタイヤ10はトレッド部20を除き従来と同様の断面構造を有するものである。空気入りタイヤ10はタイヤ幅方向両側に一対のビード部を有する。ビード部は、束ねられた鋼線にゴムが被覆されたビードコアと、ビードコアのタイヤ径方向外側に設けられたゴム部材であるビードフィラーとを有する。また、空気入りタイヤ10は、一対のビード部の間でタイヤの骨格を形成するカーカスプライを備える。カーカスプライは平行に並べられた複数のプライコードがゴムで被覆されてシート状に形成されたものである。カーカスプライよりタイヤ径方向外側には複数のベルトが積層されている。ベルトは平行に並べられた複数のコードがゴムで被覆されてシート状に形成されたものである。さらに、ベルトよりタイヤ径方向外側にはベルト補強層が設けられ、ベルト補強層よりタイヤ径方向外側にはゴム製のトレッド部20が設けられている。トレッド部20の表面は接地面14である。カーカスプライのタイヤ内側にはインナーライナーが設けられている。また、カーカスプライのタイヤ幅方向両側にはサイドウォール12が設けられている。カーカスプライのタイヤ幅方向両側であって、ビード部よりタイヤ幅方向外側にあたる位置には、ゴムチェーファーが設けられている。ゴムチェーファーの上部はサイドウォール12の下部と接している。ゴムチェーファーの表面にはリムが接する。   A pneumatic tire 10 according to this embodiment shown in FIG. 1 has a cross-sectional structure similar to that of the conventional one except for the tread portion 20. The pneumatic tire 10 has a pair of bead portions on both sides in the tire width direction. The bead portion includes a bead core in which a bundled steel wire is covered with rubber, and a bead filler that is a rubber member provided on the outer side of the bead core in the tire radial direction. The pneumatic tire 10 includes a carcass ply that forms a tire skeleton between a pair of bead portions. The carcass ply is a sheet formed by covering a plurality of parallel ply cords with rubber. A plurality of belts are laminated outside the carcass ply in the tire radial direction. The belt is formed in a sheet shape by covering a plurality of cords arranged in parallel with rubber. Further, a belt reinforcing layer is provided on the outer side in the tire radial direction from the belt, and a rubber tread portion 20 is provided on the outer side in the tire radial direction from the belt reinforcing layer. The surface of the tread portion 20 is a ground plane 14. An inner liner is provided inside the carcass ply tire. Further, sidewalls 12 are provided on both sides of the carcass ply in the tire width direction. Rubber chafers are provided at positions on both sides of the carcass ply in the tire width direction and on the outer side in the tire width direction from the bead portion. The upper part of the rubber chafer is in contact with the lower part of the sidewall 12. The rim touches the surface of the rubber chafer.

図1に示すようにトレッド部20にはタイヤ周方向に延びる4本の主溝21、22、23、24が設けられている。そして、タイヤ幅方向中央側の2本の主溝22、23に挟まれたセンター陸部30と、タイヤ幅方向中央左側の主溝22とタイヤ幅方向左側の主溝21とに挟まれた左側のメディエイト陸部31と、タイヤ幅方向中央右側の主溝23とタイヤ幅方向右側の主溝24とに挟まれた右側のメディエイト陸部32と、タイヤ幅方向両側の主溝21、24よりタイヤ幅方向外側のショルダー陸部33、34とが形成されている。センター陸部30及びメディエイト陸部31、32は、例えば、横溝で分断されることなくタイヤ周方向に連続するリブである。   As shown in FIG. 1, the tread portion 20 is provided with four main grooves 21, 22, 23, 24 extending in the tire circumferential direction. And the left side between the center land portion 30 sandwiched between the two main grooves 22 and 23 on the center side in the tire width direction, the main groove 22 on the left side in the center in the tire width direction and the main groove 21 on the left side in the tire width direction. , The mediate land portion 32 on the right side sandwiched between the main groove 23 on the right side in the tire width direction and the main groove 24 on the right side in the tire width direction, and the main grooves 21 and 24 on both sides in the tire width direction. Further, shoulder land portions 33 and 34 on the outer side in the tire width direction are formed. The center land portion 30 and the mediate land portions 31 and 32 are, for example, ribs continuous in the tire circumferential direction without being divided by a lateral groove.

図1の左側のメディエイト陸部31及び右側のメディエイト陸部32では、一方側の側壁面と他方側の側壁面とで、基準プロファイル線Lの法線方向に対する傾斜角(以下単に「傾斜角」と言う場合がある)が異なっている。そして、陸部全体が基準プロファイル線Lよりタイヤ径方向外側へ突出し、その突出の頂点が傾斜角が小さい方の側壁面側に寄っている。   In the mediate land portion 31 on the left side and the mediate land portion 32 on the right side in FIG. 1, an inclination angle with respect to the normal direction of the reference profile line L (hereinafter simply referred to as “inclination” between the side wall surface on one side and the side wall surface on the other side. “Corner” may be different). And the whole land part protrudes on the tire radial direction outer side from the reference | standard profile line L, and the vertex of the protrusion has approached the side wall surface side with a smaller inclination | tilt angle.

まず図2に示す右側のメディエイト陸部32について説明する。メディエイト陸部32は左側の側壁面41と、右側の側壁面42と、接地面14とにより形成されている。左側の側壁面41はメディエイト陸部32の左側の主溝23を形成する面でもあり、右側の側壁面42はメディエイト陸部32の右側の主溝24を形成する面でもある。このメディエイト陸部32において、左側の側壁面41の傾斜角αが、右側の側壁面42の傾斜角βよりも大きくなっている。ここで傾斜角とは、メディエイト陸部32の基準プロファイル線Lの法線方向に対する傾斜角のことである。   First, the mediate land portion 32 on the right side shown in FIG. 2 will be described. The mediate land portion 32 is formed by the left side wall surface 41, the right side wall surface 42, and the ground contact surface 14. The left side wall surface 41 is also a surface that forms the left main groove 23 of the mediate land portion 32, and the right side wall surface 42 is also a surface that forms the right main groove 24 of the mediate land portion 32. In the mediate land portion 32, the inclination angle α of the left side wall surface 41 is larger than the inclination angle β of the right side wall surface 42. Here, the inclination angle is an inclination angle with respect to the normal direction of the reference profile line L of the mediate land portion 32.

なお陸部の基準プロファイル線Lはタイヤ幅方向断面上で次のように定義される(図1参照)。まず、タイヤ赤道を有する陸部であるセンター陸部30においては、センター陸部30の幅方向の両エッジc、dと、これらと対向するメディエイト陸部31、32のエッジb、eを求め、エッジb、c、dを通る円弧とエッジc、d、eを通る円弧のうち、曲率半径の大きい方の円弧を基準プロファイル線Lとする。   The reference profile line L of the land portion is defined as follows on the cross section in the tire width direction (see FIG. 1). First, in the center land portion 30 which is a land portion having a tire equator, both the edges c and d in the width direction of the center land portion 30 and the edges b and e of the mediate land portions 31 and 32 facing these are obtained. The arc having the larger radius of curvature among the arc passing through the edges b, c, d and the arc passing through the edges c, d, e is defined as a reference profile line L.

またタイヤ赤道よりもタイヤ幅方向外側にある陸部(当該陸部とする)においては、当該陸部の両エッジと、当該陸部から見てタイヤ赤道側にある陸部における当該陸部側のエッジとを通る円弧を基準プロファイル線Lとする。具体的には、左側のメディエイト陸部31においては、メディエイト陸部31の幅方向の両エッジa、bと、センター陸部30のメディエイト陸部31側のエッジcを求め、エッジa、b、cを通る円弧を基準プロファイル線Lとする。また右側のメディエイト陸部32においては、メディエイト陸部32の幅方向の両エッジe、fと、センター陸部30のメディエイト陸部32側のエッジdを求め、エッジd、e、fを通る円弧を基準プロファイル線Lとする。   Moreover, in the land part (referred to as the land part) on the outer side in the tire width direction from the tire equator, both the edges of the land part and the land part side in the land part on the tire equator side as seen from the land part. An arc passing through the edge is defined as a reference profile line L. Specifically, in the mediate land portion 31 on the left side, both edges a and b in the width direction of the mediate land portion 31 and the edge c on the mediate land portion 31 side of the center land portion 30 are obtained. , B and c are defined as a reference profile line L. Further, in the mediate land portion 32 on the right side, both edges e and f in the width direction of the mediate land portion 32 and the edge d on the mediate land portion 32 side of the center land portion 30 are obtained, and the edges d, e, and f are obtained. The arc passing through is defined as a reference profile line L.

そして、メディエイト陸部32全体(ただし両エッジe、fを除く)が基準プロファイル線Lよりタイヤ径方向外側へ突出している。基準プロファイル線Lより突出している部分は山型となっている。そのため、基準プロファイル線Lからその法線方向に最も高く突出した点である突出の頂点44が存在する。   The entire mediate land portion 32 (excluding both edges e and f) protrudes outward from the reference profile line L in the tire radial direction. The portion protruding from the reference profile line L has a mountain shape. Therefore, there is a protruding vertex 44 that is the highest protruding point from the reference profile line L in the normal direction.

突出の頂点44は、メディエイト陸部32の幅方向の中心位置46よりも、傾斜角が小さい方の側壁面である右側の側壁面42側に寄っている。なお、図2の形態とは異なるが左側の側壁面41の方が傾斜角が小さい場合は、突出の頂点44は左側の側壁面41側に寄ることになる。   The protruding apex 44 is closer to the right side wall surface 42 side, which is the side wall surface having a smaller inclination angle than the center position 46 in the width direction of the mediate land portion 32. Although the left side wall surface 41 has a smaller inclination angle, the protruding apex 44 is closer to the left side wall surface 41 than the embodiment shown in FIG.

図2の形態において、突出の頂点44とメディエイト陸部32の幅方向の中心位置46との基準プロファイル線Lに沿った距離をX(mm)、メディエイト陸部32の幅(エッジe、f間の基準プロファイル線Lに沿った長さ)をW(mm)、左側の側壁面41の傾斜角をα(度)、右側の側壁面42の傾斜角をβ(度)、係数をtとすると、
式1:X=t×(W/2)×(α−β)/(α+β) (ただし0.8≦t≦1.2)
の関係が成立することが望ましい。式1に従えば、左側の側壁面41の傾斜角αと右側の側壁面42の傾斜角βとの差が大きいほど距離Xが大きくなる。なお係数tは任意に設定される。
In the form of FIG. 2, the distance along the reference profile line L between the protruding vertex 44 and the center position 46 in the width direction of the mediate land portion 32 is X (mm), and the width (edge e, The length along the reference profile line L between f) is W (mm), the inclination angle of the left side wall surface 41 is α (degrees), the inclination angle of the right side wall surface 42 is β (degrees), and the coefficient is t Then,
Formula 1: X = t × (W / 2) × (α−β) / (α + β) (where 0.8 ≦ t ≦ 1.2)
It is desirable that this relationship is established. According to Equation 1, the distance X increases as the difference between the inclination angle α of the left side wall surface 41 and the inclination angle β of the right side wall surface 42 increases. The coefficient t is arbitrarily set.

また、突出の頂点44の高さ(正確には突出の頂点44の基準プロファイル線Lからその法線方向への高さ)をY(mm)、係数をuとすると、
式2:Y=u×0.5mm×{1−(β/α)} (ただし0.8≦u≦1.2)
の関係が成立することが望ましい。式2に従えば、右側の側壁面42の傾斜角βが左側の側壁面41の傾斜角αに対して小さいほど、突出の頂点44の高さYが大きくなる。なお係数uは任意に設定される。例えば係数uが1.0の場合は、突出の頂点44の高さYは0.5mmを越えない。
Further, assuming that the height of the protruding vertex 44 (more precisely, the height from the reference profile line L of the protruding vertex 44 in the normal direction thereof) is Y (mm) and the coefficient is u,
Formula 2: Y = u × 0.5 mm × {1- (β / α)} (where 0.8 ≦ u ≦ 1.2)
It is desirable that this relationship is established. According to Equation 2, the height Y of the protruding apex 44 increases as the inclination angle β of the right side wall surface 42 is smaller than the inclination angle α of the left side wall surface 41. The coefficient u is arbitrarily set. For example, when the coefficient u is 1.0, the height Y of the protruding vertex 44 does not exceed 0.5 mm.

ところで、左右の側壁面41、42の傾斜角α、βが僅かでも異なる場合に、メディエイト陸部32を突出させ突出の頂点44を傾斜角が小さい方の側壁面42側に寄らせても良い。また、左右の側壁面41、42の傾斜角α、βの差が一定以上の場合に限って、メディエイト陸部32を突出させ突出の頂点44を傾斜角が小さい方の側壁面42側に寄らせても良い。好ましくは、左右の側壁面41、42の傾斜角α、βの差が3度以上の場合に、メディエイト陸部32を突出させ突出の頂点44を傾斜角が小さい方の側壁面42側に寄らせる。   By the way, when the inclination angles α and β of the left and right side wall surfaces 41 and 42 are slightly different, the mediate land portion 32 may be protruded and the protruding apex 44 may be shifted to the side of the side wall surface 42 having the smaller inclination angle. good. Further, only when the difference between the inclination angles α and β of the left and right side wall surfaces 41 and 42 is equal to or larger than a certain value, the mediate land portion 32 is protruded, and the protruding apex 44 is placed on the side of the side wall surface 42 having the smaller inclination angle. You can make it close. Preferably, when the difference between the inclination angles α and β of the left and right side wall surfaces 41 and 42 is 3 degrees or more, the mediate land portion 32 is protruded and the protruding apex 44 is placed on the side of the side wall surface 42 having the smaller inclination angle. I will stop.

次に左側のメディエイト陸部31について簡単に説明する。左側のメディエイト陸部31も、左側の側壁面51と右側の側壁面52と接地面14とにより形成されている。右側の側壁面52の傾斜角は、左側の側壁面51の傾斜角よりも大きくなっている。傾斜角及び基準プロファイル線の定義は上記の通りである。そして、メディエイト陸部31全体が基準プロファイル線よりタイヤ径方向外側へ突出しており、その突出の頂点が、メディエイト陸部31の幅方向の中心位置よりも、傾斜角が小さい方の側壁面である左側の側壁面51側に寄っている。詳細については右側のメディエイト陸部32と同様である。   Next, the mediate land portion 31 on the left side will be briefly described. The left mediate land portion 31 is also formed by the left side wall surface 51, the right side wall surface 52, and the ground contact surface 14. The inclination angle of the right side wall surface 52 is larger than the inclination angle of the left side wall surface 51. The definitions of the inclination angle and the reference profile line are as described above. The entire mediate land portion 31 protrudes outward in the tire radial direction from the reference profile line, and the apex of the protrusion is the side wall surface having a smaller inclination angle than the center position in the width direction of the mediate land portion 31. It is close to the left side wall surface 51 side. The details are the same as the mediate land portion 32 on the right side.

ここで、右側のメディエイト陸部32における左右の側壁面41、42の傾斜角の差と、左側のメディエイト陸部31における左右の側壁面51、52の傾斜角の差とが異なる場合は、左右の側壁面の傾斜角の差がより大きい方のメディエイト陸部において、他方のメディエイト陸部よりも、前記距離Xや前記高さYを大きくしても良い。そのためには、例えば、メディエイト陸部31及びメディエイト陸部32において前記距離Xや前記高さYを決定するにあたり、前記係数tや前記係数uを2つのメディエイト陸部31、32に関して同じ値として、式1や式2の計算を行う。   Here, when the difference between the inclination angles of the left and right side wall surfaces 41 and 42 in the right mediate land portion 32 is different from the difference between the inclination angles of the left and right side wall surfaces 51 and 52 in the left mediate land portion 31 The distance X and the height Y may be larger in the mediate land portion where the difference between the inclination angles of the left and right side wall surfaces is larger than in the other mediate land portion. For this purpose, for example, in determining the distance X and the height Y in the mediate land portion 31 and the mediate land portion 32, the coefficient t and the coefficient u are the same for the two mediate land portions 31 and 32. As a value, calculation of Formula 1 and Formula 2 is performed.

なお、センター陸部30では、左側の側壁面54と右側の側壁面55とで傾斜角が同じである。このように左右の側壁面の傾斜角に差が無い陸部は、基準プロファイル線よりタイヤ径方向外側へ突出していても良いし、突出していなくても良い。   In the center land portion 30, the left side wall surface 54 and the right side wall surface 55 have the same inclination angle. As described above, the land portion having no difference in inclination angle between the left and right side wall surfaces may or may not protrude outward in the tire radial direction from the reference profile line.

以上のように、メディエイト陸部31、32において右側の側壁面と左側の側壁面とで傾斜角が異なるため、そのままでは、傾斜角が小さい側壁面側のエッジ部付近の接地圧が、傾斜角が大きい側壁面側のエッジ部付近の接地圧よりも低くなり、接地圧分布に不均一性が生じる。しかし本実施形態の空気入りタイヤ10では、メディエイト陸部31、32が基準プロファイル線よりタイヤ径方向外側へ突出し、突出の頂点が傾斜角が小さい方の側壁面側にあるため、それに起因して傾斜角が小さい側壁面側のエッジ部付近の接地圧が高くなっている。その結果、メディエイト陸部31、32において、これらの幅方向の両エッジ部付近の接地圧の均衡が取れ、接地圧分布の不均一性が解消されている。   As described above, since the slope angle differs between the right side wall surface and the left side wall surface in the mediate land portions 31 and 32, the contact pressure near the edge portion on the side wall surface side where the tilt angle is small is inclined. The contact pressure becomes lower than the contact pressure in the vicinity of the edge portion on the side of the side wall having a large corner, and the contact pressure distribution becomes non-uniform. However, in the pneumatic tire 10 of the present embodiment, the mediate land portions 31 and 32 protrude outward in the tire radial direction from the reference profile line, and the apex of the protrusion is on the side of the side wall surface with the smaller inclination angle. Therefore, the contact pressure in the vicinity of the edge portion on the side wall surface with a small inclination angle is high. As a result, in the mediate land portions 31 and 32, the ground pressures in the vicinity of both edge portions in the width direction are balanced, and unevenness in the ground pressure distribution is eliminated.

ここで、左右の側壁面の傾斜角の差が大きいほど、基準プロファイル線Lよりタイヤ径方向外側への突出が無いメディエイト陸部では接地圧分布の不均一性が大きくなる。しかし、メディエイト陸部31、32が基準プロファイル線Lよりタイヤ径方向外側へ突出し、突出の頂点とメディエイト陸部31、32の幅方向の中心位置との距離Xが、上記の式1に従って左右の側壁面の傾斜角の差に応じて長くなっていれば、左右の側壁面の傾斜角の差から生じる接地圧分布の不均一性が上手く解消される。   Here, the greater the difference between the inclination angles of the left and right side wall surfaces, the greater the non-uniformity of the contact pressure distribution in the mediate land portion that does not protrude outward in the tire radial direction from the reference profile line L. However, the mediate land portions 31 and 32 protrude outward in the tire radial direction from the reference profile line L, and the distance X between the apex of the protrusion and the center position in the width direction of the mediate land portions 31 and 32 is in accordance with the above equation 1. If it becomes longer according to the difference between the inclination angles of the left and right side wall surfaces, the nonuniformity of the contact pressure distribution resulting from the difference between the inclination angles of the left and right side wall surfaces can be solved well.

また、突出の頂点の高さYが、上記の式2に従って左右の側壁面の傾斜角の差に応じて高くなっていれば、左右の側壁面の傾斜角の差から生じる接地圧分布の不均一性が上手く解消される。また、突出の頂点の高さYは上記の式2に従っていれば最大でも0.5mm前後となるため、突出の頂点の高さYが高すぎることにより却って接地圧分布の不均一性が生じることを防ぐことができる。   In addition, if the height Y of the apex of the protrusion is increased according to the difference between the inclination angles of the left and right side wall surfaces according to the above equation 2, the contact pressure distribution caused by the difference between the inclination angles of the left and right side wall surfaces is reduced. Uniformity is eliminated successfully. In addition, if the height Y of the protruding vertex is approximately 0.5 mm at the maximum according to the above formula 2, the height Y of the protruding vertex is too high. Can be prevented.

また、左右の側壁面の傾斜角の差が3度以上の場合は、そのままでは特にメディエイト陸部31、32の接地圧分布の不均一性が生じ易いため、メディエイト陸部31、32が基準プロファイル線Lよりタイヤ径方向外側へ突出し、突出の頂点が傾斜角の小さい方の側壁面側にあることの効果が大きい。   In addition, when the difference between the inclination angles of the left and right side wall surfaces is 3 degrees or more, the ground contact pressure distribution of the mediate land portions 31 and 32 is likely to be uneven as it is. The effect of projecting outward in the tire radial direction from the reference profile line L and having the apex of the projection on the side of the side wall surface with the smaller inclination angle is great.

本実施形態に対して、発明の要旨を逸脱しない範囲で、様々な変更、置換、省略等を行うことができる。例えば主溝の本数は4本に限定されず複数本であれば良い。従って2本の主溝に挟まれた陸部の数は3つに限定されない。また、2本の主溝に挟まれたいずれの陸部においても、一方側の側壁面と他方側の側壁面とで傾斜角が異なる場合は、上記実施形態におけるメディエイト陸部31、32と同様に突出させることができる。複数の陸部を突出させる場合は、一方側の側壁面と他方側の側壁面との傾斜角の差が大きい陸部ほど、突出の頂点と陸部の幅方向中心位置との距離や突出の高さを大きくしても良い。   Various changes, substitutions, omissions, and the like can be made to the present embodiment without departing from the scope of the invention. For example, the number of main grooves is not limited to four and may be plural. Therefore, the number of land portions sandwiched between the two main grooves is not limited to three. Further, in any land portion sandwiched between the two main grooves, when the inclination angle differs between the side wall surface on one side and the side wall surface on the other side, the mediate land portions 31 and 32 in the above embodiment Similarly, it can be projected. When projecting a plurality of land portions, the distance between the apex of the protrusion and the center position in the width direction of the land portion or the protrusion of the land portion is larger as the difference in inclination between the one side wall surface and the other side wall surface is larger. The height may be increased.

表1に示す比較例及び実施例の空気入りタイヤの操縦安定性及び転がり抵抗を評価した。いずれの空気入りタイヤにおいても、メディエイト陸部の左右の側壁面の傾斜角に差があり、左側の側壁面の傾斜角が15度、右側の側壁面の傾斜角が8度であった。またいずれのメディエイト陸部も幅が22mmであった。またいずれのメディエイト陸部も全体が基準プロファイル線よりタイヤ径方向外側へ突出しており、突出の頂点が存在した。   The steering stability and rolling resistance of the pneumatic tires of Comparative Examples and Examples shown in Table 1 were evaluated. In any of the pneumatic tires, there was a difference in the inclination angle of the left and right side wall surfaces of the mediate land portion, the inclination angle of the left side wall surface was 15 degrees, and the inclination angle of the right side wall surface was 8 degrees. Each mediate land portion had a width of 22 mm. In addition, all the mediate land portions protruded outward in the tire radial direction from the reference profile line, and there was an apex of the protrusion.

図3(a)に示す比較例1の空気入りタイヤでは、突出の頂点144の位置がメディエイト陸部132の幅方向中心位置であり、突出の頂点144の高さが左右の側壁面の傾斜角の差と無関係の5mm以下の固定値であった。比較例2の空気入りタイヤでは、メディエイト陸部232における突出の頂点244の位置が傾斜角の小さい側壁面側のエッジであり、突出の頂点244の高さが左右の側壁面の傾斜角の差と無関係の5mm以下の固定値であった。実施例1の空気入りタイヤでは、突出の頂点の位置が上記の式1に従った位置であり、突出の頂点の高さが上記の式2に従った高さであった。   In the pneumatic tire of Comparative Example 1 shown in FIG. 3A, the position of the protruding vertex 144 is the center position in the width direction of the mediate land portion 132, and the height of the protruding vertex 144 is the inclination of the left and right side wall surfaces. It was a fixed value of 5 mm or less irrespective of the difference in corners. In the pneumatic tire of Comparative Example 2, the position of the protruding vertex 244 in the mediate land portion 232 is an edge on the side wall surface side with a small inclination angle, and the height of the protruding vertex 244 is the inclination angle of the left and right side wall surfaces. It was a fixed value of 5 mm or less regardless of the difference. In the pneumatic tire of Example 1, the position of the top of the protrusion was a position according to the above formula 1, and the height of the top of the protrusion was a height according to the above formula 2.

評価にあたっては空気入りタイヤを適正空気圧とし適正リムに装着した。ここで適正空気圧及び適正リムとは、JATMA、TRA、ETRTO等の規格に定められている内圧及び標準リムのことである。操縦安定性については、空気入りタイヤを車両に組み付け、ドライバーが運転してフィーリング評価した。そして評価結果を指数化した。指数が大きいほど操縦安定性が良いことを意味している。転がり抵抗については、転がり抵抗試験機を用いて転がり抵抗係数を測定した。そしてその結果を指数化した。指数が小さいほど転がり抵抗が良いことを意味している。   In the evaluation, a pneumatic tire was set to an appropriate air pressure and attached to an appropriate rim. Here, the appropriate air pressure and the appropriate rim are internal pressures and standard rims defined in standards such as JATMA, TRA, and ETRTO. Regarding steering stability, pneumatic tires were assembled in the vehicle, and the driver drove the feeling of driving. The evaluation results were indexed. The larger the index, the better the steering stability. For the rolling resistance, the rolling resistance coefficient was measured using a rolling resistance tester. The results were indexed. The smaller the index, the better the rolling resistance.

結果は表1の通りである。上記実施形態に含まれる実施例1では、操縦安定性、転がり抵抗共に比較例1より良かった。これは、比較例1の空気入りタイヤではメディエイト陸部132の接地圧分布に不均一性があるのに対し、実施例1の空気入りタイヤではこの接地圧分布の不均一性が解消されたためであると考えられる。一方比較例2では、操縦安定性、転がり抵抗共に比較例1より悪かった。この原因の1つは、メディエイト陸部232の左右のエッジでタイヤ周方向への接地長の差が大きくなったことだと考えられる。   The results are shown in Table 1. In Example 1 included in the above embodiment, the handling stability and rolling resistance were both better than Comparative Example 1. This is because the contact pressure distribution of the mediate land portion 132 is non-uniform in the pneumatic tire of Comparative Example 1, whereas the non-uniformity of the contact pressure distribution is eliminated in the pneumatic tire of Example 1. It is thought that. On the other hand, in Comparative Example 2, both steering stability and rolling resistance were worse than Comparative Example 1. One reason for this is thought to be that the difference in the contact length in the tire circumferential direction at the left and right edges of the mediate land portion 232 has increased.

Figure 2017109526
Figure 2017109526

L…基準プロファイル線
10…空気入りタイヤ、12…サイドウォール、14…接地面、20…トレッド部、21、22、23、24…主溝、30…センター陸部、31、32…メディエイト陸部、33、34…ショルダー陸部、41、42…側壁面、44…頂点、46…中心位置、51、52、54、55…側壁面、132…メディエイト陸部、144…頂点、232…メディエイト陸部、244…頂点
L ... Reference profile line 10 ... Pneumatic tire, 12 ... Side wall, 14 ... Ground contact surface, 20 ... Tread part, 21, 22, 23, 24 ... Main groove, 30 ... Center land part, 31, 32 ... Mediate land , 33, 34 ... shoulder land, 41, 42 ... side wall surface, 44 ... apex, 46 ... center position, 51, 52, 54, 55 ... side wall surface, 132 ... mediate land portion, 144 ... apex, 232 ... Mediate Rikubu, 244 ... apex

Claims (3)

トレッド部にタイヤ周方向に延びる2本の主溝に挟まれた陸部を有し、前記陸部の一方側の側壁面と他方側の側壁面とで、前記陸部の基準プロファイル線の法線方向に対する傾斜角が異なる空気入りタイヤにおいて、
前記陸部全体が前記陸部の基準プロファイル線よりタイヤ径方向外側へ突出し、その突出の頂点が、前記陸部の幅方向の中心位置よりも、前記傾斜角が小さい方の側壁面側にあることを特徴とする、空気入りタイヤ。
The tread portion has a land portion sandwiched between two main grooves extending in the tire circumferential direction, and a method of a reference profile line of the land portion between a side wall surface on one side and a side wall surface on the other side of the land portion. In pneumatic tires with different inclination angles with respect to the linear direction,
The entire land portion protrudes outward in the tire radial direction from the reference profile line of the land portion, and the apex of the protrusion is on the side of the side wall surface having the smaller inclination angle than the center position in the width direction of the land portion. A pneumatic tire characterized by that.
前記突出の頂点と前記陸部の幅方向の中心位置との距離をX(mm)、前記陸部の幅をW(mm)、前記傾斜角が大きい方の側壁面の前記傾斜角をα(度)、前記傾斜角が小さい方の側壁面の前記傾斜角をβ(度)、係数をtとすると、
X=t×(W/2)×(α−β)/(α+β) (ただし0.8≦t≦1.2)
が成立する、請求項1に記載の空気入りタイヤ。
The distance between the top of the protrusion and the center position in the width direction of the land portion is X (mm), the width of the land portion is W (mm), and the inclination angle of the side wall surface having the larger inclination angle is α ( Degree), the inclination angle of the side wall surface having the smaller inclination angle is β (degrees), and the coefficient is t.
X = t × (W / 2) × (α−β) / (α + β) (where 0.8 ≦ t ≦ 1.2)
The pneumatic tire according to claim 1, wherein
前記突出の頂点の前記陸部の基準プロファイル線からの高さをY(mm)、前記傾斜角が大きい方の側壁面の前記傾斜角をα(度)、前記傾斜角が小さい方の側壁面の前記傾斜角をβ(度)、係数をuとすると、
Y=u×0.5mm×{1−(β/α)} (ただし0.8≦u≦1.2)
が成立する、請求項1又は2に記載の空気入りタイヤ。
The height of the top of the protrusion from the reference profile line of the land portion is Y (mm), the inclination angle of the side wall surface having the larger inclination angle is α (degrees), and the side wall surface having the smaller inclination angle Where the inclination angle is β (degrees) and the coefficient is u,
Y = u × 0.5 mm × {1- (β / α)} (where 0.8 ≦ u ≦ 1.2)
The pneumatic tire according to claim 1 or 2, wherein
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Publication number Priority date Publication date Assignee Title
CN110091674A (en) * 2018-01-31 2019-08-06 东洋橡胶工业株式会社 Pneumatic tire
US20220288976A1 (en) * 2019-09-03 2022-09-15 The Yokohama Rubber Co., Ltd. Pneumatic tire and green tire manufacturing method

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015147545A (en) * 2014-02-07 2015-08-20 住友ゴム工業株式会社 pneumatic tire

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015147545A (en) * 2014-02-07 2015-08-20 住友ゴム工業株式会社 pneumatic tire

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110091674A (en) * 2018-01-31 2019-08-06 东洋橡胶工业株式会社 Pneumatic tire
CN110091674B (en) * 2018-01-31 2021-02-02 东洋橡胶工业株式会社 Pneumatic tire
US20220288976A1 (en) * 2019-09-03 2022-09-15 The Yokohama Rubber Co., Ltd. Pneumatic tire and green tire manufacturing method

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