JPS60148702A - Pneumatic tyre of vehicle - Google Patents

Abstract

PURPOSE:To improve the steering stability of a FF vehicle by specifically determining both the shoulder drop ratio at the tread side corner and the ratio of the curvature radius of the round shoulder at the tread side corner with respect to the maximum width of a tyre. CONSTITUTION:The titled tyre has a round shoulder 6 at the tread side corner part thereof and has such a section as that the crown periphery 7 is smoothly connected to the side periphery 8. The shoulder drop ratio D/C, namely, the ratio of the distance D measured from the line parallel to the revolutional axis of the tyre passing through the crown top T to the crossing point P, with respect to the distance C, measured from the tyre's equator line, of the crossing point P of both the extension lines from the crown periphery 7 and the side periphery 8 which are smoothly connected to each other to have therebetween the curved line of a round shoulder 6 having a radius of curvature indicated by R3, is specified to 0.05-0.09. And the ratio R3/W, namely, the ratio of said R3 with respect to the maximum width of the tyre is specified under 0.17.

Description

【発明の詳細な説明】 （技術分野） 乗用車用空気入りタイヤなかでも前輪に比し後輪での荷
重負担がはるかに低い前輪駆動（以下ＦＦ・と略す）車
に有利に適合する工夫に関してこの明細書に述べる技術
内容は、上記荷重負担の特異性の下でとくに問題となる
操縦安定性能の向上を目指した開発成果である。[Detailed Description of the Invention] (Technical Field) Among pneumatic tires for passenger cars, this invention relates to a device that is advantageously adapted to front-wheel drive (hereinafter abbreviated as FF) vehicles, in which the load burden on the rear wheels is much lower than on the front wheels. The technical content described in the specification is the result of development aimed at improving steering stability, which is a particular problem under the above-mentioned specificity of load bearing.

（背景技術） ＦＦ車は一般に後輪荷重が、前輪荷重よりも低く、国産
の代表車種につき第１図に面荷重の関係を対比して示し
たように、それらの割合いは空車状態で大体４０：６０
より低目になっている。(Background technology) In general, the rear wheel load of FF cars is lower than the front wheel load, and as shown in Figure 1, which compares the surface load relationships for representative Japanese car models, these ratios are approximately equal to each other in the empty state. 40:60
It has become lower.

一方通常の乗用車用空気入りυイヤの荷重−コーナリン
クバワ−（以下Ｏｐで示す）の関係を一例につき第２図
に示したところから明らかなように、空気圧力（以下工
、で示す）を共通としたとき後輪のＯｐが前輪のそれよ
り非常に小さく、それ故ＦＦ車の操縦安定性能上、著し
い障害要因となる。On the other hand, as shown in Figure 2, which shows an example of the relationship between the load and corner link power (hereinafter referred to as OP) of pneumatic υ ears for ordinary passenger cars, the air pressure (hereinafter referred to as OP) is When used in common, the OP of the rear wheels is much smaller than that of the front wheels, and therefore becomes a significant impediment to the steering stability of FF vehicles.

第２図から、後輪のみ工、を低くすると接地面積の増大
でＯｐの増大され得るのは明らかであるが、転り抵抗が
増加する不利のみならず、保守の面倒が加わり実用性に
大分る。From Figure 2, it is clear that lowering the rear wheel machining can increase the ground contact area and increase OP, but this not only has the disadvantage of increased rolling resistance, but also requires troublesome maintenance, which greatly impairs practicality. Ru.

（従来技術と問題点） 上記の難点について、タイヤのトレッド幅の増加、トレ
ッドゴム、ベル゛トおよびビー゛ド部の剛性を高めるこ
とによってＯｐの増大を図ることが試みられたが、一般
に低い荷重下のＯｐ増加よりも、高荷重のそれの方が著
しいので、逆効果のおそれさえあり、さらに振動、騒音
などの居住性能や、燃費性能の悪化を伴い易く、これら
の手法の適用には限界があり、実用に適わない。(Prior art and problems) Regarding the above-mentioned difficulties, attempts have been made to increase the OP by increasing the tread width of the tire and increasing the rigidity of the tread rubber, belt, and beads, but in general, the OP is low. Since the increase in Op under high load is more significant than the increase in Op under load, there is a risk that it may even have the opposite effect.In addition, it is likely to be accompanied by deterioration of living performance such as vibration and noise, and fuel efficiency, so it is difficult to apply these methods. It has limitations and is not practical.

（発明の目的） 前輪および後輪における与を共通にしたまま、・　低荷
重側の後輪における接地性（接地幅、接地面積）を、高
荷重側の前輪のそれに比べてより大きく改善すること、
つまり、第８図に示す荷重−〇ｐ曲線■の■に至るよう
な特性の改良を導くことによって、ＦＦ車の操縦安定性
能の向上を実現することが、この発明の目的である。(Objective of the invention) While maintaining the same load on the front wheels and rear wheels, - To greatly improve the grounding performance (ground contact width, ground contact area) of the rear wheel on the low load side compared to that of the front wheel on the high load side. ,
In other words, it is an object of the present invention to improve the steering stability of a front-wheel drive vehicle by leading to an improvement in the characteristics such that the load-〇p curve (■) shown in FIG.

（発明の横取） 上記目的は次の事項を骨子とする配慮の下で有利に充足
される。すなわち、 ・　トレッド側縁がラウンドショルダをなしてクラウン
ペリフェリをサイドペリフェリと滑かに連ねる断面形状
をなす乗用車用空気入りタイヤにして、Ｒ８であられし
た曲率半径の上記ラウンドショルダの曲線を挾んでこれ
と滑かに連なるクラウンペ）リフエリとサイドペリフェ
リの各延長上の交点Ｐのタイヤ赤道面からの隔たりＯに
対する、クラウントップＴを通るタイヤの回転軸と平行
な直線からの隔たりＤの比つまり肩落比Ｄ１０が０．０
５〜０・０９でかつ上記Ｒ８のタイヤ最大幅Ｗに対する
比Ｒ８／ｗが０．１７以下であることから成る、乗用車
用空気入りタイヤ。(Misappropriation of inventions) The above purpose can be advantageously fulfilled by considering the following points. That is, - A pneumatic tire for a passenger car has a cross-sectional shape in which the tread side edge forms a round shoulder and the crown periphery smoothly connects with the side periphery, and the curve of the round shoulder with the radius of curvature of R8 is sandwiched. The ratio of the distance D from the straight line parallel to the axis of rotation of the tire passing through the crown top T to the distance O from the tire equatorial plane of the intersection point P on each extension of the periphery and the side periphery. In other words, shoulder drop ratio D10 is 0.0
5 to 0.09, and the ratio R8/w of R8 to the tire maximum width W is 0.17 or less.

上記の関係は第４図に一般図示され、図中Ｒ□ハトレッ
ドのセンタ域クラウンアール、Ｒ８はラウンドショルダ
に連るサイド域クラウンアールであり、Ｒ４はサイドペ
リフェリの曲率半径であり、０−０はタイヤの赤道面を
示す。The above relationship is generally illustrated in Fig. 4, where R□ is the crown radius of the center region of the pigeon tread, R8 is the crown radius of the side region connected to the round shoulder, R4 is the radius of curvature of the side periphery, and 0- 0 indicates the equatorial plane of the tire.

この発明の構成に従い試作したサイズ１７５／７゜５Ｒ
１８のタイヤを在来の同サイズタイヤとともに、サイズ
５′の正規リムと組合わせ、和２．４・ｋｇ　／　ｃｔ
ｄを適用したときのタイヤ断面輪郭の比較について第５
図に示し、実線がこの発明、仮想線が従来のタイヤであ
る。図中１はトレッド部、２はサイド部、８はビード部
、４はカーカス、５はベルトであり、６はラウンドショ
ルダ、７はタラウヘンペリフェリー、８はサイドペリフ
ェリーである。Size 175/7゜5R prototype made according to the configuration of this invention
Combining 18 tires with the same size conventional tires and regular size 5' rims, total weight 2.4 kg / ct
Comparison of tire cross-sectional contours when applying d
In the figure, the solid line represents the invention, and the imaginary line represents the conventional tire. In the figure, 1 is a tread portion, 2 is a side portion, 8 is a bead portion, 4 is a carcass, 5 is a belt, 6 is a round shoulder, 7 is a tarauchen periphery, and 8 is a side periphery.

一般にこの種のタイヤのＪ工Ｓ規定の工ｐは、１．７〜
であり、このときの設定荷重は正規荷重と呼ばれるがこ
れをＭであられし、正規荷重Ｍに至る荷重増加がトレッ
ドの接地幅の変動に及ぼす関係を第６図に示し、ここに
０．４Ｍでの接地幅Ｂの正規荷重ＭにおけるそれＡに対
する比Ｂ／Ａの値は、０．９〜１．０のとき、有利に適
合する。Generally, the engineering p of this type of tire is 1.7~
The set load at this time is called the normal load, which is expressed as M. Figure 6 shows the relationship that the increase in load up to the normal load M has on the variation in the contact width of the tread. The value of the ratio B/A of the ground contact width B at a normal load M to that A at a normal load M is advantageously suitable when the value is between 0.9 and 1.0.

一方正規荷重Ｍの下におけるトレッドの接地形状（フッ
トプリント）については、第７図のようＩ５にタイヤ赤
道面０−θ上に沿う接地長Ｇに対する、該赤道ｒから接
地幅端に至る隔りＥの０・９倍の位置での接地長Ｆの比
Ｆ／Ｇが０．８５〜１．１の範囲内で適合し、この比が
１．１をこえるとショルダー摩耗が懸念される。On the other hand, regarding the ground contact shape (footprint) of the tread under the regular load M, as shown in Fig. 7, I5 is the distance from the equator r to the ground contact width edge with respect to the ground contact length G along the tire equatorial plane 0-θ. The ratio F/G of the ground contact length F at a position of 0.9 times E is suitable within the range of 0.85 to 1.1, and if this ratio exceeds 1.1, shoulder wear may occur.

実測の結果によると、この発明の前記した構成１の下で
は、とくにベルトにつき、いわゆる切離しベルトの積層
構造において、０　、９　＜Ｂ／Ａ　＜１−０、かつ０
．ｓ、　５　り’／ｇ　〈１．１の関係が好ましい。According to the results of actual measurements, under the above configuration 1 of the present invention, especially for the belt, in a so-called laminated structure of a separable belt, 0, 9 < B/A < 1-0, and 0.
．． The relationship of s, 5 ri'/g <1.1 is preferable.

第５図につきさきに比較したサイズ１７５／７ｏＳＲ１
”８の試作タイヤ■および在来タイヤ０の荷重−接地幅
の関係は、第８図に示すとおりであり　Ｒ７゜〈０．９
の在来タイヤのに対しこの発明に従いＲ７゜中０．９４
となりまた、荷重−接地面積の関係につき第９図に示す
ようにとくに後輪荷重域付近にて１゛ζ前輪荷重付近で
の接地面積よりもはるかに大き−な接地面積の拡大がも
たらされた。Size 175/7oSR1 compared to Figure 5
The relationship between the load and contact width of the prototype tire ``8'' and the conventional tire 0 is as shown in Figure 8. R7゜〈0.9
0.94 in R7° according to this invention compared to the conventional tire of
Furthermore, as shown in Figure 9 regarding the relationship between load and ground contact area, the ground contact area is expanded to a much larger extent especially near the rear wheel load area than the ground contact area near the 1゛ζ front wheel load. Ta.

これらのタイヤを、１５０００ＯＦＦ小型車に装着し、
出願人会社のテストコースでの実車走行によるフィーリ
ングテストを行ったところ、在来１゛タイヤのでの操縦
安定性についての不安は実施例タイヤ■において一掃さ
れ、振動騒音などにも何らの問題は伴われなかった。Install these tires on a 15000OFF small car,
When we conducted a feeling test by driving an actual vehicle on the applicant company's test course, concerns about the handling stability of the conventional 1゛ tire were completely eliminated with the example tire ■, and there were no problems with vibration or noise. Not accompanied.

なおこの試験で荷重負担は、前輪的２５０に９、後輪的
１５　（ｕｐ　（何れもタイヤ１本当り）でありた０ （発明の効果） 以上のべたようにしてこの発明によればＦＦ車に特有な
、操縦安定性能上の不利が、この発明による後車輪側に
おける低荷重下のＣ１特性の向上により、与の低下の如
き不利を伴うことなく、有効に改善される。In this test, the load burden was 250 to 9 on the front wheels and 15 on the rear wheels. By improving the C1 characteristics under low loads on the rear wheel side according to the present invention, the disadvantages in terms of steering stability performance that are specific to the above can be effectively improved without any disadvantages such as reduction.

【図面の簡単な説明】[Brief explanation of drawings]

第１図はＦＦ車の前、後輪における荷重負担の１般傾向
グラフ、 第２図は荷重−〇ｐ関係グラフ、 第８図はＦＦ車にのぞましい荷重−Ｏｐ関係の改善の目
標を示すグラフであり、 第４図はこの発明の詳細な説明図、 第５図は実施例と従来例の比較図、 第６図は荷重−接地幅の関係グラフ、 第７図は接地形状の評価基準を示す説明図であり、 第８図は荷重−接地幅の関係比較グラフ、第９図は荷重
−接地面積関係の比較グラフでた１ネ６・・・ラウンド
ショルダ　７・・・クラウンペリフェリ８・・・サイド
ペリフェリ。 特許出願人　ブリデストンタイヤ株式会社第１図 ＦＲＯＮＴ荷愛 第２図 ｔｏｏ　ｚｏｏ　ｍ　ａｏ　ｓａｏ　ｅｏａ　ｔｓ＊）
ｆｉｔ＞第３図 ｆ５０　２０θ　２５０ 搏艶（Ｋｌ） 第６図 第７図 第８図 ａ＋ｉ愛（＃）） 第９図 １ｆＩ史（に））Figure 1 is a general trend graph of the load burden on the front and rear wheels of a FF vehicle, Figure 2 is a graph of the load-〇p relationship, and Figure 8 is a graph showing the target for improving the load-op relationship desirable for FF vehicles. Fig. 4 is a detailed explanatory diagram of the present invention, Fig. 5 is a comparison diagram between the embodiment and the conventional example, Fig. 6 is a graph of the relationship between load and ground contact width, and Fig. 7 shows evaluation criteria for ground contact shape. Fig. 8 is a comparison graph of the load-contact width relationship, and Fig. 9 is a comparison graph of the load-contact area relationship. ...Side periphery. Patent Applicant: Brideston Tire Co., Ltd. (Figure 1) FRONT Cargo (Figure 2)
fit> Fig. 3 f50 20θ 250 Kl Fig. 6 Fig. 7 Fig. 8 a+i love (#)) Fig. 9 1fI history (ni))

Claims (1)

【特許請求の範囲】[Claims] Ｌ　トレッド側縁がラウンドショルダをなしてクラウン
ペリフェリをサイドペリフェリと滑かに連ねる断面形状
をなす乗用車用空気入りタイヤにして、Ｒｓであられし
た曲率半径の上記ラウンドショルダの曲線を挾んでこれ
と滑かに連なるクラウンペリフェリとサイドペリフェリ
ーの各延長上の交点Ｐの、タイヤ赤′道面からの隔たり
Ｏに対する、クラウントップＴを通るタイヤの回転軸と
平行な直線からの隔たりＤの比、っまり肩落比が０．０
５〜０．０９でかつ上記Ｒ８のタイヤ最大幅Ｗに対する
比が０．１７以下であることを特徴とする、乗用車用空
気入りタイヤ。L A pneumatic tire for a passenger car has a cross-sectional shape in which the tread side edge forms a round shoulder and the crown periphery smoothly connects with the side periphery, and this is made by sandwiching the curve of the round shoulder with a radius of curvature of Rs. The distance D from the straight line parallel to the axis of rotation of the tire passing through the crown top T with respect to the distance O from the tire equatorial plane of the intersection point P on each extension of the crown periphery and side periphery that smoothly connect. Ratio, shoulder drop ratio is exactly 0.0
5 to 0.09 and a ratio of R8 to the tire maximum width W of 0.17 or less.