JP4308932B2 - Heavy duty pneumatic tire - Google Patents

Description

上記の表１から明らかなように、実施例のタイヤは、コーナリングパワー（ＣＰ）については比較例１のタイヤより高く、ころがり抵抗（ＲＲ）については比較例１，２よりも小さくなり、また偏摩耗については比較例とほとんど差のないものとなった。
【００３７】
【発明の効果】
上記のように本発明の重荷重用空気入りタイヤによれば、所定のトレッド幅、接地面積を確保して、同時に荷重負荷によるショルダー部への応力集中を防ぎ、低転がり抵抗化できる上、タイヤ側面のバットレス部の耐カット性にも優れるものとなる。
【００３８】
さらに、タイヤ更新のためのバフラインがタイヤ側面と交わる個所のバットレス部表面に位置するように形成されているため、タイヤの更新性をも良好に確保できる。
【図面の簡単な説明】
【図１】本発明の重荷重用タイヤのラジアル方向に沿う断面図である。
【図２】同上の一部の拡大断面図である。
【図３】タイヤ更新加工状態の説明図である。
【図４】従来のタイヤの一部の断面図である。
【図５】従来タイヤの一部の断面図である。
【符号の説明】
（Ｔ） タイヤ
（１） トレッド部
（２） サイドウォール部
（４） ビード部
（５） カーカス
（６） ベルト層
（６ａ） 最外ベルト層
（７） 主溝
（８） 陸部
（９） バットレス部
（１０） 環状凹陥部
（10ａ） 凹部
（１１） 環状リブ
（ｅ） トレッド端
（Ｌ） バフライン[0001]
BACKGROUND OF THE INVENTION
The present invention relates mainly to heavy duty pneumatic tires for trucks, buses and the like.
[0002]
[Prior art and problems to be solved by the invention]
As a heavy-duty pneumatic tire for trucks, buses, etc., it has a plurality of main grooves continuous in the tire circumferential direction in the tread part, and has mainly rib-shaped land parts at both ends of the tread, and the tread end (shoulder 2. Description of the Related Art A so-called square shoulder type tire is known in which an end) is formed at an edge to form a box shape as a whole.
[0003]
Such tires tend to have a wider tread width because the wider the tread width and the larger the contact area, the better the wear resistance, the handling stability, and the grip performance on icy and snowy road surfaces. On the other hand, when the tread width is increased, the contact pressure of the tread end portion (shoulder portion) is remarkably increased locally, and uneven wear such as shoulder dropping at the tread end portion is likely to occur.
[0004]
In order to reduce the uneven wear, a narrow groove (22) is provided slightly inside the tread end (e) of both side end portions (23) of the tread portion (21) as shown in FIG. In some cases, the increase in the contact pressure is suppressed. In this case, however, the substantial tread width and contact area are reduced, and in addition, stone biting occurs in the narrow groove (22) and cracks occur in the groove bottom. Or problems such as chipping of the tread edge may occur.
[0005]
Therefore, by making the tread end part protrude from the side of the original shoulder to the side, and widening the tread width, the end of the tread is projected by the movement of the protruding tread while ensuring a large ground contact area. Has proposed a tire structure that absorbs the pressure increase at the front (Japanese Patent Laid-Open No. 4-189604).
[0006]
However, when the tread width (TW) is increased by projecting the end of the tread portion (21) to the side as described above, the ground contact area is increased as shown in FIG. The buttress part (29) on the inner side in the tire radial direction of the part (25) has a concave shape, so when the tire side surface comes into contact with a curb or the like, the buttress part (29) has a poor escape and cuts to the tire side surface. There is a problem that is likely to occur.
[0007]
In addition, if the belt width is left as it is and the tread edge protrudes to the side, the highly rigid contact surface unique to radial tires is difficult to maintain, which increases the movement within the tread surface and causes rolling resistance due to hysteresis loss. There is also a tendency to get worse.
[0008]
In addition, heavy load pneumatic tires are generally renewed and reused by replacing the tread portion outside the belt with a renewal tread when a certain amount of wear has progressed.
[0009]
This renewal process is usually performed by buffing (scraping) the tread part, leaving a rubber thickness of at least about 2.5 mm on the outside of the outermost belt layer of the tire, and attaching a plate-like rehabilitation tread to this part. And unite them together. As the method, since the renewal processing part is only the tread part, a large vulcanizing kettle with a pre-formed renewal tread pasted on the surface of the buffed base tire via an adhesive layer is used. In many cases, a so-called cold type renewal method of joining by re-vulcanizing and joining is adopted.
[0010]
At this time, if there is a concave portion on the side surface of the tire that intersects with the buff line, the tread width of the renewal tire becomes narrower than the original tread width. There is a problem that it becomes difficult to match the width of the joint surface with the pedestal tire, or that the tire has a renewed tire with a narrower tread width than the initial tire and impairs the wear life.
[0011]
The present invention has been made in view of the above, and ensures a predetermined tread width and a ground contact area, and at the same time, prevents stress concentration on the shoulder portion due to a load load, lowers rolling resistance, and particularly on the tire side surface. The present invention provides a heavy-duty pneumatic tire excellent in cut resistance at a buttress portion, and further provides a heavy-duty pneumatic tire capable of ensuring good renewability of the tire.
[0012]
[Means for Solving the Problems]
The heavy-duty pneumatic tire of the present invention that solves the above problems has an unrenewed pneumatic tire having a plurality of main grooves continuous in the tire circumferential direction in the tread portion, and at least land portions on both side ends of the tread. An annular recess extending in the tire circumferential direction is provided in the buttress portion on the tire radial side from the tread end on the side surface of the tire, and the annular recess is divided into a plurality of recesses 1 or a plurality of annular ribs are provided, the annular recess is that not make uneven in the tire radial direction cross-section.
[0013]
With this heavy-duty pneumatic tire, a predetermined tread width, that is, a contact area can be secured, and an increase in contact pressure and stress concentration at the end portion (shoulder portion) of the tread can be absorbed by the annular recess. In particular, since the annular recess is divided into a plurality of recesses by one or a plurality of annular ribs to form an uneven shape, the stress can be effectively dispersed and absorbed by a compressive deformation action caused by a load applied to each recess. For this reason, stress concentration in the shoulder portion can be prevented, rolling resistance can be reduced, and cornering power can be maintained well.
[0014]
In the heavy-duty pneumatic tire of the present invention, in addition to the above configuration, one of the annular ribs of the annular recess has a height that reaches at least the tire side line, and is the outermost part for tire replacement. A buff line in the case of buffing the tread portion while leaving a predetermined rubber thickness outside the belt layer is formed so as to be positioned on the buttress portion surface where the tire side surface intersects .
[0015]
For this reason, when it is necessary to renew the tread portion due to the wear of the tire more than a predetermined amount, a predetermined rubber thickness, for example, a rubber thickness of about 2.5 mm is provided on the outer side of the outermost belt layer. It is scraped off by buffing, but on the surface of the buttress where the buff line intersects the side of the tire, there is an annular rib located on the side of the tire, not on the concave in the annular recess. Therefore, there is no problem that it is difficult to match the width of the joint surface between the renewal tread and the base tire or the renewal tread is narrow.
[0016]
Therefore, in the updated tire, the initial predetermined tread width can be secured, and the tread width and the contact area can be prevented from decreasing.
[0017]
The annular recess is preferably formed so as to be gradually shallower from the center toward both ends in the tire radial direction. In this case, since the heights of the plurality of recesses and the annular rib in the annular recess are different and the bending at the time of load is different, the stress concentration is absorbed well and the appearance of the annular recess is also good. Become a thing.
[0018]
The heavy duty pneumatic tire targeted by the present invention is a tire for trucks and buses having a tire width of 165 mm or more, an oblateness of 90% or more, and a rim diameter of 15 inches or more, and is mainly used for front wheels. Is.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0020]
FIG. 1 is a cross-sectional view along the tire width direction showing one embodiment of an unrenewed heavy duty pneumatic tire (T) of the present invention . FIG. 2 is an enlarged sectional view of a part of the above.
[0021]
In the figure, (1) is a tread portion of a tire (T), (2) is a sidewall portion extending outwardly in the tire radial direction from bead portions (4) on both sides including a bead core (3), and both ends thereof are tread portions. Connected with (1). A belt layer (6) comprising a carcass (5) whose ends are folded back and supported by bead cores (3) along the inner periphery, and comprising a plurality of layers between the tread portion (1) and the carcass (5). It has. If necessary, a reinforcing layer made of a fiber cord or the like is disposed outside the belt (6). The internal structure of such a tire is basically the same as that of a conventionally known radial tire structure, and a detailed description thereof will be omitted.
[0022]
Further, as shown in FIG. 1, the tread portion (1) has a plurality of main grooves (7) (four in the figure) continuous in a straight or zigzag shape in the tire circumferential direction, and at least the tread. It has rib-like land portions (8) mainly at both end portions of the portion (1), and in the case of the figure, the central region of the tread portion (1) is also rib-shaped separated by the main groove (7). It is based on a rib pattern having a land portion (8). In the land portion (8), there may be formed a lateral groove called a relatively thin slit connecting the main grooves (7) if necessary, and a narrow groove called a sipe may also be formed. is there.
[0023]
The tread end (e) where the tread surface of the shoulder portion (13) and the tire side surface by the land portion (8) outside the outermost main groove (7) and the tire side surface intersect each other end portion of the tread portion (1), It is a so-called square shoulder type tire formed on a box-shaped edge. The tread end (e) may be slightly rounded.
[0024]
In the case of the present invention, as shown in the figure, the buttress portion (9 ) including the side surface of the tread portion (1) below the tread end (e) in the tire that has not been renewed , that is, the tread end (e) inside the tire radial direction. ) Is provided with an annular recess (10) that extends in the tire circumferential direction in a cross-sectional shape with a hollow shape (recessed shape) from the original tire side surface. The annular recess (10) is provided with one or a plurality of annular ribs (11) that divide the inside into a plurality of recesses (10a) in the tire radial cross section, and the annular recess (10) is a tire diameter. It is uneven in the cross section.
[0025]
The annular recess (10) is not limited to an annular shape that is continuous in the tire circumferential direction, but may be intermittent at various locations in the circumferential direction, and may be substantially annular as a whole. . Further, the annular recess (10) is provided at a position below a point about 2/3 of the main groove depth from the tread end (e) so that it can be used while maintaining a predetermined tread width (TW) until the tire is renewed. Is desirable.
[0026]
The annular recess (10) is preferably formed to be gradually shallower from the center toward both ends in the tire radial direction, and the annular rib (11) in the annular recess (10) is as shown in the figure. What has the height which reaches at least a tire side surface line is preferable from the point of cut resistance and the stress absorption effect of a shoulder part.
[0027]
Among them, one of the annular ribs (11) has a height that reaches at least the tire side line, leaving a predetermined rubber thickness (t1) outside the outermost belt layer (6a) for tire replacement. A buff line (L) for buffing the tread portion (1), for example, conventionally, when a tire is renewed, it is buffed leaving a rubber thickness of about 2.5 mm outside the outermost belt layer (6a). Therefore, a line assumed about 2.5 mm outside from the outermost belt layer (6a) is defined as a buff line (L), and the line (L) is positioned on the surface of the buttress portion (9) where the line intersects the tire side surface. It is particularly suitable for the tire renewal processing to be formed in this manner.
[0028]
That is, in the tire renewal processing when the wear exceeds a predetermined level, as shown in FIG. 3, the tread portion (1) of the tire (T) is about 2.5 mm outside the outermost belt layer (6a). The rubber tread (1) is scraped off so as to leave the rubber thickness (t1), and the renewal tread (1a) is pasted on the buffed surface to be joined and integrated. At this time, the buff line (L) intersects the tire side surface. Since the annular rib (11) exists on the surface of the buttress part (9) at a certain place, not the recess (10a), the tread width according to the original tire side face can be secured at the part of the joint surface with the renewal tread. Therefore, there is no problem that it is difficult to match the width of the joining surface of the renewal tread and the base tire or the width of the renewal tread becomes narrow, and an renewed tire having an initial tread width can be obtained.
[0029]
In addition, as an uneven | corrugated shape by the annular rib (11) and recessed part (10a) of the said annular recessed part (10), in addition to what makes a cross-sectional waveform by a comparatively smooth curve like a figure, a cross section is substantially trapezoid or substantially A triangular irregular shape may be used, but those having a corrugated cross-section have no stress concentration, and those in which an annular rib (11) is positioned at the intersection of the buff line and the tire side surface are particularly preferable.
[0030]
In addition, the said annular recessed part (10) is perpendicular | vertical with respect to a tire axial center from the point (a) of a tire inner side 1 to 4% of tread width from a tread end (e), for example, a point of 5 mm tire inner side. When the vertical line is lowered, it is preferable that the deepest part of the annular recess (10) is located outside the vertical line.
[0031]
In the case of the heavy-duty pneumatic tire of the above-described embodiment, even if the buttress portion (9) has an annular recess (10) due to the counterbored shape from the side of the original tire, a predetermined tread width (TW), that is, a predetermined The ground contact area can be secured, and the increase in contact pressure and stress concentration at the tread end (shoulder portion) can be absorbed by the annular recess (10). In particular, the annular recess (10) is divided into a plurality of recesses (10a) by one or a plurality of annular ribs (11) to form an uneven shape, so that the compressive deformation due to a load applied to each recess (10a). The action reduces the side stiffness and can effectively disperse and absorb the stress concentration. For this reason, stress concentration of the shoulder portion (1a) can be prevented, rolling resistance (RR) can be reduced, uneven wear such as shoulder dropping hardly occurs, and the cornering power (CP) is also maintained well.
[0032]
For example, in the tire of the rib pattern having the structure of FIG. 2 having the annular recess in the buttress portion, the tire of the embodiment having a tire size of 285 / 75R24.5 14PR, and a narrow groove formed slightly on the tread end in FIG. For a conventional tire of the same size (Comparative Example 1) and a tire of the same size (Comparative Example 2) of FIG. 5 with the tread ends protruding sideways, the rolling resistance (RR), cornering power ( CP) and uneven wear were measured and compared, and the results were as shown in Table 1 below.
[0033]
The cornering power (CP) is the average of the absolute values of lateral forces measured at 10 km / h by adding a 2 ° slip angle to the left and right in a bench test to a tire set to standard load and standard internal pressure. It is a value divided by a slip angle of 2 °, and is represented by an index with Comparative Example 1 being 100.
[0034]
The rolling resistance (RR) was measured after running for 1 hour at 60 km / h by the force measurement method of “JATMA truck and bus tire rolling resistance test method”. It was.
[0035]
For uneven wear, a drum test was performed, and the tire shoulder end state after running 6700 km at 24.5 × 8.25 rim, internal pressure 850 kPa, load 150% of standard, speed 40 km / h and visually evaluated. Comparative example 1 was set as 100 and indicated as an index.
[0036]
[Table 1]

As apparent from Table 1 above, the tire of the example has a cornering power (CP) that is higher than that of the comparative example 1, and a rolling resistance (RR) that is smaller than those of the comparative examples 1 and 2. The wear was almost the same as that of the comparative example.
[0037]
【The invention's effect】
As described above, according to the heavy-duty pneumatic tire of the present invention, a predetermined tread width and a ground contact area can be secured, and at the same time, stress concentration on the shoulder due to load can be prevented, and the rolling resistance can be reduced. The cut resistance of the buttress part is also excellent.
[0038]
Furthermore, since the Bafurain for tires updates are formed to be located buttress portion surface locations intersecting with the tire side, it is also secured satisfactorily update of the tire.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view along the radial direction of a heavy duty tire of the present invention.
FIG. 2 is an enlarged sectional view of a part of the above.
FIG. 3 is an explanatory diagram of a tire update processing state.
FIG. 4 is a partial cross-sectional view of a conventional tire.
FIG. 5 is a partial cross-sectional view of a conventional tire.
[Explanation of symbols]
(T) Tire (1) Tread part (2) Side wall part (4) Bead part (5) Carcass (6) Belt layer (6a) Outermost belt layer (7) Main groove (8) Land part (9) Buttress Part (10) annular recess (10a) recess (11) annular rib (e) tread end (L) buff line

Claims (2)

  An unrenewed pneumatic tire having a plurality of main grooves continuous in the tire circumferential direction in the tread portion and having land portions at least at both ends of the tread, the tread on the inner side in the tire radial direction from the tread end on the tire side surface The buttress part including the side surface of the part is provided with an annular recess extending in the tire circumferential direction, and the annular recess is provided with one or more annular ribs that divide the interior into a plurality of recesses, The annular recess is uneven in the tire radial cross section, and at least one of the annular ribs of the annular recess has a height that reaches at least the tire side line. The buff line when the tread part is buffed leaving a predetermined rubber thickness on the outside is formed so as to be located on the buttress part surface where it intersects the tire side surface. Heavy duty pneumatic tire according to claim. 2. The heavy duty pneumatic tire according to claim 1, wherein the annular recess is formed so as to be gradually shallower from the center toward both ends in the tire radial direction.

Images