【考案の詳細な説明】[Detailed explanation of the idea]
産業上の利用分野
ラグタイプトレツドパターンを有する空気入り
タイヤには、いわゆるハイラグタイプに代表され
る農耕作業機械類の走行車輪に供用されるもの
と、厚肉ラグ配列において主に運搬又は産業用機
械類に装着されるヘビーデユーテイラグタイプと
に大別され、かような使途の違いに由来したそれ
ぞれの長所、短所を有しているが、これら長、短
のうち、両者の長所のみの有利な統合によつて上
記使途の区別には格別依存することなく、ハイラ
グタイプにはもちろんヘビーデユーテイラグタイ
プにも、有利に適用することができる段付きラグ
タイヤについての開発成果を提案しようとするも
のである。
（従来の技術）
ハイラグタイプのタイヤは、主に水田などの軟
弱地域において
ラグの深い食い込みを生じ必要なトラクシヨ
ンが得られ易い
反面、硬質地域での大牽引作業に使用したと
き、ラグ欠けやクラツクの如き損傷を受ける
おそれがあるほか加硫中に深いモールドキヤ
ビテイヘのゴムの流動に帯同されてケースボデ
イーのカーカスプライのいわゆる吸込みによ
り、コードの打込みにばらつきを来たしたり、
また内面波打ちのためラグ間のスキツドベース
ゲージの贅肉を生じたりして強度およびコスト
面での不利
が伴われる。
一方において硬質路面用に適合するヘビーデユ
ーテイラグタイプのタイヤは、ラグの肉厚もラグ
テーパーさらにはラグの付け根の丸味半径も大き
いので、
大牽引時のラグ欠けやラグテイアのおそれは
少ないが軟弱地域ではラグの食い込みが悪い
こと、また転動中にラグの動きが殆んどない
のでラグ間に挟まつた泥土が脱落し難くて、つ
まりが生じ易いこと
とが相俟つて走行中にスリツプを起こす欠点
をもつ。
しかるに、これら両ラグタイプの各型式に依存
する長所のみを結集することによつて両タイプの
タイヤに通じる兼用を図るような試みがなされた
事例の報告を見ることができない。
（考案が解決しようとする問題点）
ハイラグタイプタイヤの上掲、ヘビーデユー
テイタイプタイヤの上記の各長所を結集し、そ
れぞれの上述、並びに〜の欠点の悉くを
排除することにより軟弱地帯におけるラグの食い
込みをよくするとともに、泥はけに必要なラグ屈
撓性を生じるように、トレツド寄りのラグ肉厚つ
まりラグ頂面厚みをハイラグタイプ並みに小さく
保つことにあわせ、硬質地帯走行中におけるラグ
欠けないしはクラツクが生じ難いように、ラグの
付け根の根本幅を太くすることの構想の下に、ラ
グの前面および／または後面に段面を設けて、走
行路表の土質の相反するような使途の如何に拘ら
ず共通に適切なタイヤ走行を可能ならしめる段付
きラグタイヤを提案することがこの考案の目的で
ある。
（問題点を解決するための手段）
この考案はトレツドの中央円周の両側にてその
中央円周上からトレツドの側端まで互い違いに傾
斜してのびる多数のラグをそなえ、これらのラグ
はトレツド側からラグの付け根に向つて漸増する
ラグ肉厚を有してそれぞれトレツドの中央円周に
沿う間隔をおく配置としたラグタイヤにして、
ラグの付け根に向う上記ラグ肉厚の漸増域の途
中からラグ肉厚が急増する段面をラグの前面と背
面のうち少なくとも片面に有することを特徴とす
る段付きラグタイヤである。
ここにラグ肉厚の漸増は、ラグ頂面のエツジか
らラグの付け根に向つて拡がるテーパーそれも該
エツジに立てたトレツド表面の法線に対する傾き
θ1，θ2が８〜15゜程度の角度とする。この肉厚漸
増減の途中、つまりラグ高さの30〜80％に相当す
る距離をラグ頂面からへだてる位置での上記テー
パによつて定まる中間厚みに対して1.05〜1.20倍
程度の拡大厚みになるように、段面を張出させ
る。
（作用）
ラグ肉厚はその頂面すなわちトレツド側で従来
ハイラグタイプ並みに薄いため、軟弱地における
路表への食い込みは鋭く、また同じくトレツド寄
りにて柔軟なため泥落ちもよく、従つてラグ間で
の泥づまりが生じにくくなり、他方トレツド側と
は反対のラグの付け根に至る中間に段面を有する
分、ラグの付け根がより肉厚化されるので、硬質
路面上での大牽引力下にラグ欠けやクラツクの心
配も軽減される。
（実施例）
さて第１図ａ，ｂには、主として水田での農耕
トラクタの如きに多用される従来のハイラグタイ
プタイヤを、サイズ12.4−28の例につき、トレツ
ド上におけるラグの１単位の配列と、その筋目と
直交する断面とで示し、図中１，１′はトレツド
の中央円周の両側にてその中央円周上からトレツ
ドの側端まで互い違いに傾斜してのびる配列とし
た一対のラグ、２はその頂面で上掲サイズではほ
ぼ26mm程度の厚みとされる。また３，４はラグ
１，１′の踏込み側すなわち前面と、蹴出し側つ
まり背面で、それぞれラグの付け根の方に向つて
拡がるテーパーの傾き角度θ1，θ2ともこの例でお
のおの15゜，15゜程度以下の傾斜をもつものとさ
れ、さらにこのテーパーとスキツドベースが約30
mmの曲率半径の丸味によつて滑らかに連ねられて
ラグの付け根を形成する。なお上記テーパーの傾
斜角度の設計の都合で8゜程度まで変更されること
がある。
これに対し第２図には従来の硬質土用ヘビーデ
ユーテイラグタイプのタイヤにおける歯筋直交断
面を示し、上例と同等サイズで厚みがほぼ30mm程
度の頂面２′から、この例で前面３′および後面
４′ともテーパーの角度θがほぼ25゜の傾斜を附
し、ラグの付け根は前面３′で50mm、背面４′は90
mm程度の曲率半径の丸味をもつて、スキツドベー
スと滑らかに連ねられている。
これに対して第３図、第４図にはこの考案に従
う段付きラグタイヤの各別実施例を段面５がラグ
１，１′の前面３と、後面４とにそれぞれ形成さ
れた各場合について、第１図に挙げた従来例と同
等サイズのハイラグタイプにおいてラグテーパー
の傾きは各θ1，θ2につき15゜、頂面２の厚みＷは
ほぼ26mmそしてラグ１，１′の付け根の丸味の曲
率半径は前、後面とも30mmの円弧とした例で図示
し、何れの場合もラグ１，１′のラグ高さＨ（51
mm）に対して69％に相当する距離d1（35mm）を頂
面２から隔てる位置で上記傾斜によるテーパーで
定まる中間厚みW1（44.8mm）に対してこの厚み方
向への段面５の投影長さ（約５mm）を含む拡大厚
みW2（49.8mm）を1.1倍程度にする段面５を設ける
ことによつてハイラグタイプにはもとよりヘビー
デユーテイラグタイプにも兼用することを可能な
らしめる。
上記した第４図に従う供試タイヤを、同サイズ
の段面を有しない従来のハイラグタイプととも
に、それぞれ30％および50％スリツプ時のトラク
シヨンについて比較し次表の成績が得られた。
Industrial applications Pneumatic tires with a lug-type tread pattern include those used for running wheels of agricultural machinery such as the so-called high-lug type, and those with thick-walled lug arrangements that are mainly used for transportation or industrial applications. It is roughly divided into heavy duty lug types that are installed on industrial machinery, and each has its own advantages and disadvantages due to the difference in usage. We have developed a stepped lug tire that can be advantageously applied not only to the high-lug type but also to the heavy-duty lug type, without relying particularly on the above-mentioned usage distinction, due to the advantageous integration of This is what I am trying to propose. (Conventional technology) High-lug type tires tend to have deep lugs that dig in, making it difficult to obtain the necessary traction mainly in soft areas such as rice fields.On the other hand, when used for large-scale traction work in hard areas, lugs may chip or break. In addition to the risk of damage such as cracks, the so-called suction of the carcass ply of the case body caused by the flow of rubber into the deep mold cavity during vulcanization may cause unevenness in the insertion of the cord.
In addition, the inner surface corrugation causes the skid base gauge to become thick between the lugs, resulting in disadvantages in terms of strength and cost. On the other hand, heavy-duty lug type tires that are suitable for hard road surfaces have thicker lugs, a larger lug taper, and a larger rounded radius at the base of the lug, so there is less risk of lug chipping or lug tear during heavy traction. In soft areas, the lugs do not penetrate well, and since there is almost no movement of the lugs during rolling, it is difficult for mud caught between the lugs to fall off, making them more likely to clog, which can cause slips while driving. It has the disadvantage of causing However, there have been no reports of cases in which an attempt has been made to achieve universal use for both types of tires by combining only the advantages that depend on each type of these lug types. (Problem to be solved by the invention) By combining the above-mentioned advantages of the high-lug type tire and the above-mentioned advantages of the heavy-duty type tire, and eliminating all of the above-mentioned disadvantages and ... In order to improve the lug biting in and to provide the lug flexibility necessary for mud removal, the lug wall thickness near the tread, that is, the lug top surface thickness, was kept as small as the high lug type. With the idea of increasing the width of the base of the lug so that it is difficult for the lug to chip or crack inside, a stepped surface is provided on the front and/or rear side of the lug to prevent conflicts between the soil types of the running road surface. The purpose of this invention is to propose a stepped lug tire that enables suitable tire running regardless of the intended use. (Means for Solving the Problem) This device has a number of lugs on both sides of the central circumference of the tread extending in an alternating manner from the central circumference to the side edges of the tread, and these lugs are connected to the tread. The lug tire has a lug thickness that gradually increases from the side toward the base of the lug, and is arranged at intervals along the center circumference of the tread, and from the middle of the area where the lug thickness gradually increases toward the base of the lug. This stepped lug tire is characterized in that it has a stepped surface on at least one of the front and back surfaces of the lug where the lug wall thickness rapidly increases. Here, the gradual increase in the lug thickness is due to the taper that spreads from the edge of the top surface of the lug toward the base of the lug, and the inclinations θ 1 and θ 2 with respect to the normal line of the tread surface set on the edge are about 8 to 15 degrees. shall be. In the middle of this gradual increase/decrease in wall thickness, that is, at the position where the lug leaves away from the top surface by a distance equivalent to 30 to 80% of the lug height, the intermediate thickness determined by the above taper is expanded by about 1.05 to 1.20 times. Extend the stepped surface so that it is thick. (Function) The lug wall thickness is as thin as the conventional high lug type on the top surface, that is, the tread side, so it cuts into the road surface sharply on soft ground, and it is also flexible on the tread side, so it removes mud easily. Mud clogging between the lugs is less likely to occur, and on the other hand, the base of the lug is made thicker due to the stepped surface in the middle leading to the base of the lug on the opposite side from the treaded side, so it can withstand large traction forces on hard road surfaces. There is also less worry about lag chips and cracks. (Example) Figures 1a and b show examples of conventional high-lug type tires, which are often used on agricultural tractors in rice fields, with sizes 12.4-28, and one unit of lug on the tread. In the figure, 1 and 1' are a pair of treads arranged on both sides of the center circumference of the tread, extending in an alternating manner from the center circumference to the side edge of the tread. The lug, 2, is the top surface, which is said to be approximately 26 mm thick in the size listed above. Further, 3 and 4 are the stepping side or front side and the kicking side or back side of the lugs 1 and 1', respectively, and the inclination angles θ 1 and θ 2 of the tapers expanding toward the base of the lugs are each 15° in this example. , with an inclination of about 15 degrees or less, and this taper and skid base are said to have an inclination of about 30 degrees or less.
They are smoothly connected by roundness with a radius of curvature of mm to form the base of the lug. Note that the inclination angle of the taper mentioned above may be changed to about 8° due to design considerations. On the other hand, Fig. 2 shows a cross section perpendicular to the tooth traces of a conventional heavy-duty lug type tire for hard soil. The taper angle θ of both the front 3' and rear 4' is approximately 25 degrees, and the base of the lug is 50 mm at the front 3' and 90 mm at the rear 4'.
It has a rounded radius of curvature of about mm and is smoothly connected to the skid base. On the other hand, FIGS. 3 and 4 show different embodiments of the stepped lug tire according to this invention, in which the stepped surfaces 5 are formed on the front surface 3 and the rear surface 4 of the lugs 1 and 1', respectively. , in the high lug type of the same size as the conventional example shown in Fig. 1, the slope of the lug taper is 15° for each θ 1 and θ 2 , the thickness W of the top surface 2 is approximately 26 mm, and the base of the lugs 1 and 1' The radius of curvature of the roundness is shown as an example with a circular arc of 30 mm on both the front and rear surfaces, and in both cases, the lug height H of lugs 1 and 1' (51
The height of the stepped surface 5 in this thickness direction with respect to the intermediate thickness W 1 (44.8 mm) determined by the taper due to the above-mentioned inclination at a position separated from the top surface 2 by a distance d 1 (35 mm) corresponding to 69% of the distance (mm). By providing a stepped surface 5 that increases the expanded thickness W 2 (49.8 mm) including the projected length (approximately 5 mm) by approximately 1.1 times, it can be used not only for the high-lug type but also for the heavy-duty lug type. Make it seem possible. The test tire shown in FIG. 4 above was compared with a conventional high-lug type without a stepped surface of the same size in terms of traction at 30% and 50% slip, respectively, and the results shown in the following table were obtained.
【表】
この比較試験は、試験車両にロードセルを介し
て可変おもりをつないで水田中にて走行させ負荷
の増加によつて生じるスリツプが30％および50％
になるときのロードセルの読みからトラクシヨン
を測定し、比較タイヤの性能を100とする指数に
よつて評価したものである。
なお第３図のように、よりスキツドベース側の
付け根でさらにラグ高さＨに対し10〜20％に相当
する距離d2をスキツドベースから隔てる位置でラ
グ１，１′の前面３に第２の段面６を形成してラ
グの付け根をさらに強化することもできる。
上記のようにして、この考案によるとラグ１，
１′の付け根側でのラグ厚みが適切に増すので、
従来のハイラグタイプタイヤの加硫中にしばしば
問題となつていたような、深いラグキヤビテイへ
の局部的なトレツドゴムの激しい吸込みがトレツ
ド周にて分散されるため、ケースボデイーのコー
ド乱れ、それもとくにラジアル構造カーカスプラ
イによるケース補強をもつラジラルタイヤにおけ
る著しい不利についてはもちろん、それに伴われ
る内面形状不整、さらにラグ間スキツドベースゲ
ージの贅肉などの不利が何れも有利に軽減される
上、硬質路表上での強い牽引力の作用に対して高
い抵抗の下にラグ欠けやクラツクを生じるうれい
もなく、そして頂面におけるラグ肉厚は薄いまま
なので軟弱地帯での走行に必要な鋭い路表への食
い込みを生じ、また適度に柔軟で走行中のラグの
動きにより泥づまりを生じにくく、泥はけ性能も
有利に維持される。
（考案の効果）
ハイラグタイプタイヤでの要求性能とくにトラ
クシヨンについての事実上の劣化ないしに、
であげた欠点を有利に克服して、ヘビーデユーテ
イラグタイプタイヤにおけるの利点のみがハイ
ラグタイプタイヤに取込まれ、また逆にヘビーデ
ユーテイラグタイプタイヤでの要求性能につい
ても事実上の劣化を伴わずに〜でまとめた欠
点を有利に克服して、ハイラグタイプタイヤ並び
にヘビーデユーテイラグタイプタイヤ双方の利点
が吸収されることになつて、軟弱地帯、硬質路表
を通して、両ラグタイプに固有の長所を、単一タ
イヤによつて兼備することができる。[Table] In this comparative test, a variable weight was connected to the test vehicle through a load cell, and the vehicle was run in rice fields, and the slip caused by the increase in load was 30% and 50%.
The traction was measured from the load cell reading when the tire was used, and evaluated using an index with the performance of the comparative tire set as 100. As shown in Fig. 3, a second step is installed on the front surface 3 of the lugs 1 and 1' at a distance d 2 corresponding to 10 to 20% of the lug height H from the skid base at the base closer to the skid base. A surface 6 can also be formed to further strengthen the base of the lug. As described above, according to this invention, lag 1,
The lug thickness at the base of 1' increases appropriately, so
As the localized strong suction of the tread rubber into the deep lug cavity, which was often a problem during vulcanization of conventional high-lug type tires, is dispersed around the tread circumference, the cord disturbance of the case body, especially Not only are the significant disadvantages of radial tires with case reinforcement using radial structure carcass plies, but also the disadvantages of the resulting irregular inner surface shape and the excess weight of the skidded base gauge between the lugs, etc. There is no risk of lug chipping or cracking due to high resistance to the action of strong traction forces, and the lug thickness at the top remains thin, so it does not dig into the sharp road surface necessary for driving in soft terrain. It is also moderately flexible, making it difficult for mud to become clogged due to the movement of the lugs while driving, and maintaining mud removal performance advantageously. (Effects of the invention) No deterioration or deterioration in the required performance, especially traction, of high-lug type tires.
By advantageously overcoming the disadvantages listed above, only the advantages of heavy-duty lug-type tires are incorporated into high-lug-type tires, and conversely, the required performance of heavy-duty lug-type tires is virtually eliminated. By advantageously overcoming the disadvantages summarized in ~ without deterioration of the tires, the advantages of both high-lug type tires and heavy-duty lug type tires are absorbed, and the tires can be used in soft areas and on hard roads. The inherent advantages of both lug types can be combined in a single tire.
【図面の簡単な説明】[Brief explanation of drawings]
第１図ａ，ｂは従来のハイラグタイプタイヤの
ラグ配列図とラグ断面図、第２図は同じくヘビー
デユーテイラグタイプタイヤのラグ断面図、第３
図、第４図はこの考案の各別実施例を示すラグ断
面図である。
Ｃ……トレツドの中央円周、１，１′……ラグ、
２……頂面、３……前面、４……後面、５，６…
…段面。
Figures 1a and b are a lug arrangement diagram and a lug sectional view of a conventional high-lug type tire, Figure 2 is a lug sectional view of a heavy-duty lug type tire, and Figure 3 is a lug sectional view of a conventional high-lug type tire.
4 are lug sectional views showing different embodiments of this invention. C...Central circumference of the tread, 1,1'...Lug,
2...Top surface, 3...Front surface, 4...Rear surface, 5, 6...
...dan side.