JP2004276763A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire in which a separation of belt layers is prevented to improve the durability of a crossing belt by setting a uniform formation of an inter-chord distance of the tire in its diameter direction of the belt layers constituting a crossing belt. <P>SOLUTION: A pneumatic tire 1 is provided with a belt 5 on an outer circumference of a crown part 3 of a carcass 2 which comprises at least two-layered belt layer having reinforcing elements extending while being inclined at a relative low angle in respect to a tire equator surface E covered with rubber. There are provided a first belt layer 4a and a second belt layer 4b of the belt layers constituting this laminated belt to cause the reinforcing elements to cross to each other while holding the tire equator surface E. A wedge-like edge rubber having its thickness gradually decreased toward the extremity end is arranged between the end portions of the first belt layer 4a and the second belt layer 4b. An inter-chord distance in a tire diameter direction of the first belt layer 4a and the second belt layer 4b is more than 0.5 times of that at the tire equator surface position at either the extremity end position of the edge rubbers 6 or its adjoining position. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３２】
表１に示す結果から、実施例１〜９のタイヤはいずれも、比較例１〜３のタイヤに比べて耐久性に優れていることが分かる。
【００３３】
【発明の効果】
この発明により、交差ベルトを構成する第１及び第２ベルト層のタイヤ径方向コード間距離の均一化を図って、かかるベルト層間でのセパレーションを有効に防止し、ベルトの耐久性を向上させた空気入りタイヤを提供することが可能となった。
【図面の簡単な説明】
【図１】この発明に従う代表的な空気入りタイヤの要部断面図である。
【図２】図１に示すタイヤのベルト及びエッジゴムの拡大図である。
【図３】この発明に従うタイヤに使用可能な種々のエッジゴムを示す。
【図４】この発明に従う他の空気入りタイヤの幅方向右半断面図である。
【図５】この発明に従う他の空気入りタイヤの幅方向右半断面図である。
【図６】この発明に従う種々の空気入りタイヤの幅方向右判断面図である。
【符号の説明】
１ タイヤ
２ カーカス
３ クラウン部
４ａ 第１ベルト層
４ｂ 第２ベルト層
５ ベルト
６ エッジゴム
７ シート部
８ 楔部
９、１２ ゴムシート
１０、１３ ゴムシートのタイヤ幅方向内側端縁
１１ エッジゴムのタイヤ幅方向内側端縁[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire having a crossed belt composed of belt layers in which reinforcing elements are stacked so as to intersect with each other across a tire equatorial plane on the outer periphery of a crown portion of a carcass, and in particular, to improve the durability of such a tire. Aim.
[0002]
[Prior art]
Conventionally, in heavy-duty pneumatic tires used for large vehicles such as trucks and buses, by arranging a plurality of belt layers, crossed belts sequentially stacked so that reinforcing elements cross each other, high internal pressure and It is designed to withstand heavy loads. However, in such an intersecting belt, when the tire rolls, a shearing force acts between these adjacent belt layers, and especially at both ends of the belt layer where stress tends to concentrate, a reinforcing element and a rubber covering the reinforcing element are used. There is a problem that separation easily occurs between the two.
[0003]
In order to solve such a problem, for example, Patent Document 1 discloses that an edge rubber having a wedge-shaped cross section is disposed between adjacent belt layers constituting a cross belt, thereby suppressing fatigue crack damage around a belt end portion and preventing occurrence of separation. Described pneumatic tires. However, in such a tire, the distance between cords in the tire radial direction of the adjacent belt layer tends to be locally shorter than other positions due to the arrangement of the edge rubber. As a result, the cord-to-cord distance is concentrated at the tip position of the edge rubber or the like, which may cause separation between adjacent belt layers.
[0004]
[Patent Document 1]
JP-A-7-251605
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to improve the durability of the belt by effectively preventing the separation between the belt layers by making the distance between the tire radial direction cords of the belt layers constituting the cross belt uniform. To provide a pneumatic tire.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a rubber coating of a reinforcing element which extends at a relatively small angle with respect to the tire equatorial plane on the outer periphery of a crown portion of a carcass extending in a toroidal shape between a pair of bead portions. A belt comprising at least two belt layers, wherein two of the belt layers constituting the belt are laminated so that the reinforcing elements intersect each other across the equatorial plane of the tire to form an intersecting belt. In a pneumatic tire that is a first and a second belt layer of the upper and lower belt layers, a wedge-like shape whose thickness gradually decreases toward the front end between the end portions of the first and second belt layers in a cross section in the tire width direction. Wherein the distance between the cords in the tire radial direction of the first and second belt layers is at least 0.5 times the tire equatorial plane position at or near the tip end position of the edge rubber. It is a pneumatic tire.
[0007]
Further, it is preferable that the edge rubber further has a sheet portion having a substantially uniform thickness extending inward in the tire width direction from a tip end thereof.
[0008]
Further, the thickness of the seat portion is preferably in a range of 0.5 to 1.0 times the distance between the cords in the tire radial direction in the first and second belt layers on the tire equatorial plane.
[0009]
Furthermore, the distance measured from the edge of the first belt layer to the tip of the edge rubber along the tire width direction is preferably in the range of 0.3 to 0.6 times the half width of the first belt layer.
[0010]
In addition, a rubber sheet having a substantially uniform thickness is disposed between the edge rubber and the second belt layer, and the inner edge of the rubber sheet in the tire width direction is larger than the inner edge of the edge rubber in the tire width direction. It is preferable to be located on the inner side in the width direction.
[0011]
In addition, a rubber sheet having a substantially uniform thickness is disposed between the edge rubber and the first belt layer, and the inner edge of the rubber sheet in the tire width direction is larger than the inner edge of the edge rubber in the tire width direction. It is preferable to be located inside the tire width direction.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a main part of a typical pneumatic tire (hereinafter, referred to as “tire”) according to the present invention, and FIG. 2 is a portion when only a belt and an edge rubber are extracted from the tire shown in FIG. It is an enlarged view.
[0013]
The tire 1 shown in FIG. 1 has a relatively small angle with respect to the tire equatorial plane E, preferably 14 to 14, on the outer periphery of a crown portion 3 of a carcass 2 extending in a toroidal shape between a pair of bead portions (not shown). At least two belt layers obtained by rubber-coating a reinforcing element extending at an angle of 30 °, a first belt layer 4a which is an upper belt layer located outside in the tire radial direction in FIG. The belt 5 includes two belt layers, that is, a second belt layer 4b which is a lower belt layer located thereon. The belt layers 4a and 4b constituting the belt 5 are stacked so that the reinforcing elements intersect each other with the tire equatorial plane E interposed therebetween to form an intersecting belt.
[0014]
The main feature in the configuration of the present invention is that a wedge-shaped edge rubber 6 whose thickness gradually decreases toward the tip is provided between the end portions of the first and second belt layers 4a and 4b in the cross section in the tire width direction. 2, the distance between the tire radial direction cords of the first and second belt layers 4a and 4b is 0.5 times or more the tire equatorial plane position at or near the tip position of the edge rubber, that is, FIG. That is, the distance g is 0.5 times or more the distance a.
[0015]
Hereinafter, a description will be given of how the present invention adopts the above configuration together with its operation. As described above, in a tire provided with a cross belt, when the tire rolls, a shearing force acts between adjacent belt layers, and particularly at both ends of the belt layer where stress tends to concentrate, the reinforcing element and the There is a problem that separation easily occurs with the rubber to be coated. In order to solve this problem, it is known to dispose an edge rubber between the first and second belt layers of the cross belt. In this case, the arrangement of the edge rubber suppresses the separation at the belt end. However, there is a possibility that separation between belts may newly occur at a position where the distance between the cords in the tire radial direction of the first and second belt layers is short.
[0016]
The inventor has conducted intensive studies on the cause, and if edge rubber is disposed between the first and second belt layers, the separation at the belt end is suppressed, but the distance between these tire radial cords is not uniform. The deviation was found to be large. That is, the inter-cord distance is minimized at or near the tip position of the edge rubber and gradually increases toward the tire equatorial plane, and the ratio of the inter-cord distances at both positions is as small as less than 0.5. When applied, stress concentrates at the location where the inter-cord distance is minimized, resulting in separation between the first belt layer and the second belt layer. Then, the inventor increases the ratio of the inter-cord distance at the tip end position of the edge rubber or the vicinity thereof to the inter-cord distance at the tire equatorial plane position, that is, reduces the deviation of the inter-cord distance, and stress concentrates. By eliminating the portions, it has been found that separation can be effectively suppressed, and as a result, the durability of the tire can be improved, and the present invention has been completed.
[0017]
Further, from the viewpoint of more effectively suppressing the separation, the distance between the tire radial cords of the first and second belt layers 4a and 4b is 0.6 to less than 0.6 to the tire equatorial plane position at or near the tip end of the edge rubber. It is preferably 1.4 times, and more preferably 1.0 times from the viewpoint of making the distance between codes uniform.
[0018]
It is preferable that the edge rubber 6 further has a substantially uniform thickness sheet portion 7 extending inward in the tire width direction from the front end thereof as shown in FIG. This is because, as a result of the inter-cord distance approaching more uniformly, the separation between the first belt layer 4a and the second belt layer 4b can be more effectively suppressed.
[0019]
In addition, FIG. 3A shows an embodiment in which the sheet portion 7 and the wedge portion 8 are integrally formed to form the edge rubber 6, but as shown in FIG. The wedge part 8 may be separate. In this case, from the viewpoint of preventing stress concentration, the distance f between the sheet portion 7 and the wedge portion 8 is preferably 0 to 2 mm.
[0020]
The thickness b of the seat portion 6 may be in a range of 0.2 to 1.0 times the distance a between the tire radial cords of the first belt layer 4a and the second belt layer 4b on the tire equatorial plane E. preferable. When the thickness b of the seat portion is less than 0.2 times the distance a between the cords in the tire radial direction of the first and second belt layers on the tire equatorial plane E, the deviation of the distance between the cords should be made sufficiently small. This is because the effect of arranging the seat portion 7 is not sufficiently exhibited. When the ratio exceeds 1.0 times, the effect of tightening the belt at the end of the belt becomes insufficient, so that when the vehicle is running, etc. This is because the diameter growth of the cross belt becomes excessive and separation at the belt end may occur. From the viewpoint of productivity, the thickness b of the seat portion 6 may be at least 0.4 times the distance a between the tire radial direction cords of the first belt layer 4a and the second belt layer 4b on the tire equatorial plane E. More preferably, from the viewpoint of durability, it is more preferably less than 0.8 times.
[0021]
Further, the distance d measured along the tire width direction from the first belt layer 4a to the tip of the edge rubber, measured along the tire width direction, is 0.3 to 0.6 times the half width c of the first belt layer. Is preferably within the range. If the distance d is less than 0.3 times the half width c of the first belt layer, the length of the sheet portion 7 becomes insufficient and stress concentrates on the front end of the sheet portion 7. If it exceeds 0.6 times, the buckling effect at the end of the belt will be insufficient, and the diameter growth of the cross belt during running will be excessive, This is because separation at the end may occur.
[0022]
Furthermore, from the viewpoint of more effectively suppressing the separation, the distance d measured from the first belt layer 4a to the front end of the seat portion along the tire width direction is 0.35 to 0 of the half width c of the first belt layer. More preferably, it is in the range of .50.
[0023]
In addition, as shown in FIG. 4, a rubber sheet 9 having a substantially uniform thickness is provided between the edge rubber 6 and the second belt layer 4b, and the rubber sheet 9 has an inner edge 10 in the tire width direction. Is preferably located on the inner side in the tire width direction than the inner edge 11 in the tire width direction of the edge rubber. This is because, as a result of the inter-cord distance approaching more uniformly, the separation between the first belt layer 4a and the second belt layer 4b can be more effectively suppressed.
[0024]
In addition, as shown in FIG. 5, a rubber sheet 12 having a substantially uniform thickness is provided between the edge rubber 6 and the first belt layer 4a, and the inner edge of the rubber sheet 12 in the tire width direction is provided. 13 is preferably located on the inner side in the tire width direction than the inner edge 11 in the tire width direction of the edge rubber 6. This is because, as a result of the inter-cord distance approaching more uniformly, the separation between the first belt layer 4a and the second belt layer 4b can be more effectively suppressed.
[0025]
And when manufacturing such a tire, the second belt layer is stuck on the forming drum, or on the third belt layer stuck in advance as necessary, and then, on the second belt layer, both ends thereof After the edge rubber is applied over a range of 1/4 to 1/3 of the width of the second belt layer, the first belt layer is formed into a reinforcing element forming the second belt layer with the tire equatorial plane interposed therebetween. A cross belt is formed by laminating so as to cross, and then, if necessary, a fourth belt layer is stuck, and then a tread rubber is stuck to manufacture a BT band. Thereafter, the BT band is fitted to the green case, and after performing predetermined shaping, performing other steps generally required for tire manufacture, such as pasting of other tire components and vulcanization, to thereby obtain the tire according to the present invention. Is obtained.
[0026]
The above description is only an example of the embodiment of the present invention, and various changes can be made within the scope of the claims. For example, as shown in FIGS. 3C and 3D, the edge rubber 6 may have a flat portion 7 on the outer side in the tire width direction. 6A to 6C, the edges of the belt layers 4a and 4b are covered with the edge rubber 6 and the rubber sheets 9 and 12, from the viewpoint of more effectively suppressing the separation at the belt end. May be.
[0027]
【Example】
Next, a pneumatic tire according to the present invention was prototyped and its performance was evaluated, and will be described below.
[0028]
The tires of Examples 1 to 9 are radial tires for trucks and buses having a tire size of 275 / 80R22.5, in which the belt is composed of four belt layers, and the width of each belt layer is in the tire radial direction. It is 160 mm, 180 mm, 160 mm, and 80 mm, respectively, in order from the inside, and the edge rubber is disposed between the second second belt layer and the third first belt layer counted from the inside in the tire radial direction. It has the specifications shown. The edge rubbers of Examples 1 and 2 do not have a sheet portion, and the edge rubbers of Examples 3 to 5 have a sheet portion integrated with a wedge portion inside the tire width direction, and the edge rubbers of Examples 6 and 7 Has a sheet portion separate from the wedge portion on the inner side in the tire width direction, and the edge rubber of Example 8 has no sheet portion, but is substantially uniform between the edge rubber and the first belt layer. Although a rubber sheet having a thickness is provided, the edge rubber of Example 9 does not have a sheet portion, but a rubber sheet having a substantially uniform thickness is provided between the edge rubber and the second belt layer. are doing.
[0029]
For comparison, the tire size and the belt were the same as those of Examples 1 to 9 and had the specifications shown in Table 1, and the edge rubber had no sheet portion (Comparative Example 1), and the edge rubber was in the tire width direction. Tire having a wedge portion and a separate sheet portion on the inside (Comparative Example 2), a rubber sheet having no sheet portion but having a substantially uniform thickness between the edge rubber and the first belt layer although the edge rubber does not have a sheet portion. The tire (Comparative Example 3) provided with was also prototyped.
[0030]
(Test method)
Each of the test tires was mounted on a standard rim (8.25) specified by JATMA to form a tire wheel. The tire wheel was heated to a temperature of 70 ° C. under an air pressure of 760 kPa (relative pressure, oxygen partial pressure of 380 kPa) and no load. After leaving it in a constant temperature bath for 2 weeks to promote oxygen deterioration of the tire rubber, the tire was run on a drum tester under the conditions of an air pressure of 760 kPa (relative pressure), a tire load of 2800 kN, and a running speed of 60 km / h. The running distance until the tire broke down was measured, and the tire durability was evaluated based on the measured distance. Table 1 shows the evaluation results.
[0031]
[Table 1]

[0032]
From the results shown in Table 1, it can be seen that all of the tires of Examples 1 to 9 are more excellent in durability than the tires of Comparative Examples 1 to 3.
[0033]
【The invention's effect】
According to the present invention, the distance between cords in the tire radial direction of the first and second belt layers constituting the cross belt is made uniform, separation between the belt layers is effectively prevented, and the durability of the belt is improved. It has become possible to provide pneumatic tires.
[Brief description of the drawings]
FIG. 1 is a fragmentary cross-sectional view of a representative pneumatic tire according to the present invention.
FIG. 2 is an enlarged view of a belt and edge rubber of the tire shown in FIG.
FIG. 3 shows various edge rubbers that can be used in a tire according to the invention.
FIG. 4 is a right half sectional view in the width direction of another pneumatic tire according to the present invention.
FIG. 5 is a right half sectional view in the width direction of another pneumatic tire according to the present invention.
FIG. 6 is a right side view in the width direction of various pneumatic tires according to the present invention.
[Explanation of symbols]
Reference Signs List 1 tire 2 carcass 3 crown portion 4a first belt layer 4b second belt layer 5 belt 6 edge rubber 7 sheet portion 8 wedge portion 9, 12 rubber sheet 10, 13 inner edge of rubber sheet in tire width direction 11 edge rubber in tire width direction Inside edge

Claims (6)

A belt comprising at least two belt layers in which a reinforcing element extending at a relatively small angle to the tire equatorial plane is rubber-coated on the outer periphery of a crown portion of a carcass extending in a toroidal shape between a pair of bead portions. And two of the belt layers constituting the belt are first and second belts of upper and lower belt layers in which reinforcing elements are stacked so as to intersect with each other with the tire equatorial plane interposed therebetween. In the pneumatic tire that is
In the cross section in the tire width direction, a wedge-shaped edge rubber whose thickness gradually decreases toward the tip is disposed between the end portions of the first and second belt layers, and the tire radial cords of the first and second belt layers are provided. A pneumatic tire, wherein the distance is 0.5 times or more the tire equatorial plane position at or near the tip end of the edge rubber. 2. The pneumatic tire according to claim 1, wherein the edge rubber further has a sheet portion having a substantially uniform thickness extending inward in the tire width direction from a tip end thereof. 3. The pneumatic tire according to claim 2, wherein the thickness of the seat portion is in a range of 0.2 to 1.0 times a distance between cords in the tire radial direction in the first and second belt layers on the tire equatorial plane. The distance measured along the tire width direction from the edge of the first belt layer to the tip of the edge rubber is in a range of 0.3 to 0.6 times a half width of the first belt layer. A pneumatic tire according to one of the preceding claims. A rubber sheet having a substantially uniform thickness is disposed between the edge rubber and the second belt layer, and the inner edge of the rubber sheet in the tire width direction is more inner than the inner edge of the edge rubber in the tire width direction. The pneumatic tire according to any one of claims 1 to 4, wherein A rubber sheet having a substantially uniform thickness is disposed between the edge rubber and the first belt layer, and the inner edge of the rubber sheet in the tire width direction is more inner than the inner edge of the edge rubber in the tire width direction. The pneumatic tire according to any one of claims 1 to 5, wherein

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