JP3839581B2 - Pneumatic tire - Google Patents

Description

【００４６】
テストの結果、実施例のタイヤは、標準のリムを使用しつつしかもタイヤ重量の大幅な増加を伴わずしてランフラット性能を向上していることが確認できた。なお、前記比（Ｌ／Ｈｃ）が小さいほどランフラット性能を良くなるが耐摩耗性能が著しく損なわれるため実用には適さないことが確認できた。なおランフラット指数と、前記比（Ｌ／Ｈｃ）との関係を、各供試タイヤ毎に図９に示している。
【００４７】
【発明の効果】
以上説明したように請求項１又は３記載の発明では、前記カーカス高さＨｃと、カーカスビード点Ａからカーカスバットレス点Ｂまでの半径方向距離Ｌとの比（Ｌ／Ｈｃ）を限定することによって、ランフラット走行時のタイヤ内腔面の摩擦接触部の滑りを抑制し、この部分でのカーカスコードの破断などを比較的長時間にわたり防止しうる。
【００４８】
また前記フランジ被覆域の長さ（Ｐ〜Ｃ）をフランジ露出長さ（Ｐ〜Ｄ）よりも３mm以上大とすることによって、ランフラット走行時にこのフランジ被覆域がリムフランジを十分に巻き込んで、かつ前記リブの頂部近傍がリムフランジの外側点Ｄに引っかかるようにして被覆することが可能となり、リム外れをより一層防止できる。
【００４９】
さらにフランジ被覆域には、タイヤ外方に向けて凸となる凸曲面部と凹曲面部とを設けているため、凸曲面部がランフラット走行時に曲率を反転させてリムフランジを覆被することでより強い力でリムフランジを保持し、しかもその半径方向外側に設けられた凹曲面部がさらにフランジ外側点Ｄを巻き込むように作用するため、リム外れがより一層防止され、ランフラット走行距離を増大させうる。
【００５０】
また請求項２記載の発明では、前記フランジ被覆域Ｆの前記凸曲面部の曲率半径Ｒ１を前記凹曲面部の曲率半径Ｒ２よりも大とすることによって、前記リム外れ防止効果をさらに向上しうる。
【図面の簡単な説明】
【図１】本発明の実施の一形態を示す空気入りタイヤの断面図である。
【図２】ビード部を拡大して示す断面図である。
【図３】タイヤのパンク走行状態を示す断面図である。
【図４】従来のフランジ被覆域を説明するビード部の断面図である。
【図５】そのパンク状態を示す断面図である。
【図６】本実施形態のタイヤのパンク状態を示す断面図である。
【図７】実施例の具体的寸法を示す図である。
【図８】従来例の具体的寸法を示す図である。
【図９】ランフラット指数と、比（Ｌ／Ｈｃ）との関係を示すグラフである。
【符号の説明】
２ トレッド部
３ サイドウォール部
４ ビード部
５ ビードコア
６ カーカス
７ ベルト層
１１ リム外れ防止リブ
Ｊ 正規リム[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire that does not come off the rim even when air in the tire escapes due to puncture or the like and can travel a relatively long distance.
[0002]
[Background Art and Problems to be Solved by the Invention]
Conventionally, various pneumatic tires have been proposed that have improved so-called run-flat performance that does not come off the rim even when air in the tire escapes due to puncture or the like and that can travel a relatively long distance.
[0003]
For example, a reinforcing rubber layer or the like is provided on the sidewall portion to suppress bending of the sidewall portion at the time of puncture (Japanese Patent Laid-Open No. 53-18104, Japanese Patent Laid-Open No. 64-30809, Japanese Patent Laid-Open No. 2-281289, etc.) ), A rim that prevents rim disengagement at the time of puncture (for example, Japanese Patent Laid-Open No. 52-64701, Japanese Patent Laid-Open No. 2-31905, etc.), and a tire lumen surrounded by the tire and the rim With a core or protector that suppresses vertical deflection of the tire during puncture (Japanese Patent Laid-Open Nos. 55-132313, 60-213508, 61-235207), tubeless tires And a rim that is surrounded by a tube that supports a tire load only at the time of puncture (JP-A-2-34402, JP-A-58-1) JP), etc. 0604 is proposed.
[0004]
However, in the case where the reinforcing rubber layer is provided in the sidewall portion, the tire weight becomes extremely heavy, and there is a problem that the rolling resistance is increased and the fuel efficiency is deteriorated. Further, in recent studies, it has been found that such a tire provided with a reinforcing rubber layer on the sidewall portion can easily be detached from the rim, although it can reduce the vertical deflection at the time of puncture.
[0005]
In addition, for special rims that prevent rim detachment at the time of puncture, specially shaped rims must be manufactured, which increases costs and requires industry standard approval etc. It is not popular in the market.
[0006]
Furthermore, in the case where a core that suppresses the vertical deflection of the tire at the time of puncture is provided in the tire lumen, the core interferes with the tire rim assembly workability, and the core is used as a rim. A special technique is required to set, and there are problems such as an increase in wheel weight.
[0007]
Also, if a tube that supports the tire load only at the time of puncture is arranged in the tire lumen surrounded by the tubeless tire and the rim, the rim assembly workability of the tire is significantly impaired, the wheel weight is increased, and the internal tube In the case of a penetrating wound that reaches, there are problems such as being useless.
[0008]
As for run-flat performance, it is only necessary to temporarily avoid the inability to drive due to tire puncture, and more specifically, it is necessary to travel from a punctured place to a place where it is possible to safely repair tires such as a gas station. For example, in the United States, the goal is to be able to travel about 80 km at a speed of 80 km / h.
[0009]
The present invention has been devised in view of the above-described problems, and can be used for general tire performance, for example, a standard rim, can maintain rim assemblability, and is not accompanied by a significant increase in tire weight. The object of the present invention is to provide a pneumatic tire capable of improving the run-flat performance.
[0010]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention is a pneumatic tire comprising a carcass extending from a tread portion to a bead core of a bead portion through a sidewall portion, and an inner liner rubber on a tire lumen surface. The height from the bead base line BL to the radially outermost position of the center line of the thickness of the carcass in a normal tire meridional section in which the rim is assembled to the normal rim, the normal internal pressure is filled, and no load is applied. From the carcass bead point A where the carcass height Hc and the radial line N passing through the rim width position of the regular rim intersect the carcass center line at the bead part, the radial line N intersects the carcass center line at the buttress part. The ratio (L / Hc) to the radial distance L to the carcass buttress point B is 0.30 to 0.45, and the outer surface of the bead portion and the bead A rim detachment preventing rib protruding outward in the axial direction is formed radially outward from a flange separation point P where the portion is separated from the rim flange of the regular rim, and the top of the rim detachment prevention rib is formed from the flange separation point P. The length (P to C) along the outer surface of the flange covering area up to the rib top point C is along the rim flange from the flange separation point P of the normal rim to the axially outermost point D of the rim flange. The flange-covered area is 3 mm or more larger than the flange exposure length (P to D), and the flange-covered area is smoothly connected to the convex curved surface portion protruding outward from the tire and radially outward of the convex curved surface portion. And a concave curved surface portion.
[0011]
The invention according to claim 2 is the pneumatic tire according to claim 1, wherein the convex curved surface portion has a curvature radius R1 larger than a curvature radius R2 of the concave curved surface portion.
[0012]
The invention according to claim 3 is an assembly of a tire and a rim, in which the tire according to claim 1 or 2 is assembled to the regular rim.
[0013]
In the present specification, the “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, a standard rim for JATMA and a “Design Rim” for TRA. Or "Measuring Rim" for ETRTO.
[0014]
In addition, “regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. It is the maximum air pressure for JATMA and the table “TIRE LOAD LIMITS” for TRA. The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO, but 180 kPa when the tire is for passenger cars.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In the present embodiment, as shown in FIG. 1, a carcass 6 extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, a belt layer 7 disposed on the outer side in the tire radial direction of the carcass 6, A tubeless type radial tire for a passenger car having an inner liner rubber 10 on the tire lumen surface i is illustrated. FIG. 1 shows an assembly of a tire and a rim in which the tire is assembled on a regular rim J and filled with a regular internal pressure and is unloaded.
[0016]
The pneumatic tire of the present embodiment is an example in which the outer surface of the tire from the tread portion 2 to the vicinity of the tire maximum width position of the sidewall portion 3 is formed by smoothly connecting arcs with gradually reduced curvature radii. is doing.
[0017]
The carcass 6 is composed of one or more radial plies, in this example, one ply, in which carcass cords are arranged at an angle of 75 ° to 90 ° with respect to the tire equator C. As the carcass cord, an organic fiber cord such as nylon, rayon or polyester is used in this example.
[0018]
The carcass 6 has a main body portion 6 a that extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and a folded portion 6 b that extends from the main body portion 6 a and is turned around the bead core 5. A bead apex 8 made of hard rubber extending from the bead core 5 to the outside in the tire radial direction is disposed between the main body portion 6a and the turn-up portion 6b to reinforce the bead portion 4. Yes.
[0019]
The belt layer 7 includes at least two belt plies 7A and 7B in which the cords are arranged at a small angle of 15 to 40 ° with respect to the tire equator, and in this example, the cords cross each other. It is configured by overlapping in the direction. The belt cord employs a steel cord in this example, but a highly elastic organic fiber cord such as aramid or rayon may be used as necessary.
[0020]
Further, in this example, the belt layer 7 is provided on the outer side in the tire radial direction with a band layer 9 in which nylon cords are arranged substantially parallel to the tire equator C at an angle of 5 ° or less. This improves durability during high-speed driving.
[0021]
The inner liner rubber 10 is made of a rubber that hardly permeates air, such as butyl rubber, halogenated butyl rubber, or brominated butyl rubber. In the present embodiment, the inner liner rubber 10 is disposed on the tire lumen surface i with a thickness of 1 mm or more and 3 mm or less. This is an example.
[0022]
Then, in the normal meridional section of the tire in which the tire is assembled to the normal rim J and filled with the normal internal pressure and is unloaded, the carcass 6 is connected to the carcass 6 from the bead base line BL that is the tire axial direction line passing through the rim diameter position. The carcass height Hc, which is the height of the thickness center line Lc to the radially outermost position T, and the radial line N passing through the rim width position of the normal rim J are the bead portions 4 and the carcass center line Lc. The ratio (L / Hc) of the radial direction line N from the intersecting carcass bead point A to the carcass buttress point B where the radial line N intersects the carcass centerline Lc in the buttress portion 3a is 0.30 to 0.45. Yes.
[0023]
In general, during run-flat running with a punctured tire, as shown in FIG. 3, the buttress portion 3a and the bead portion 4 are brought into contact friction on the tire lumen surface i, and by continuing running in such a state, The inner liner rubber 10 and the topping rubber in this portion are worn or thermally destroyed, and as a result, the cord of the carcass 6 is broken. Also, if the carcass cord breaks, a very large vibration is generated, so it is necessary to give up traveling.
[0024]
As a result of various experiments, the present inventors have found that reducing the sliding of contact friction between the buttress portion 3a and the bead portion 4 on the tire inner surface i is effective for breaking the carcass cord during run-flat running. In order to reduce the slip, the inventors have found that it is necessary to limit the ratio (L / Hc) to a range of 0.30 to 0.45.
[0025]
Here, when the ratio (L / Hc) exceeds 0.45, the slip of the buttress portion 3a and the bead portion 4 tends to increase on the tire lumen surface i during run-flat running. Below 30, the slip itself becomes small, but the tire becomes very round in the meridional section of the tire, and the wear resistance performance generally required for the tire is remarkably deteriorated such that the central portion of the tread is prematurely worn. . The ratio (L / Hc) is preferably 0.30 to 0.40.
[0026]
As described above, the pneumatic tire of the present embodiment has a ratio (L) between the carcass height Hc and the radial distance L from the carcass bead point A to the carcass buttress point B without increasing the tire weight. By limiting / Hc), it is possible to suppress slipping of the frictional contact portion of the tire cavity surface i during run-flat traveling, and to suppress breakage of the carcass cord at this portion for a relatively long time.
[0027]
The center line Lc of the carcass is defined with respect to the main body 6a of the carcass and not included with respect to the turn-up portion 6b.
[0028]
In this embodiment, the outer surface of the bead portion 4 and the rim detachment prevention rib 11 projecting outward in the axial direction and radially outward from the flange separation point P where the bead portion 4 is separated from the rim flange Jf of the regular rim J. Is forming.
[0029]
Such a rim detachment prevention rib 11 can effectively prevent the tire from being detached from the rim during the run-flat running and being unable to run. In the present invention, the configuration of the rim detachment prevention rib 11 is further limited. By doing so, it is possible to further prevent the rim from coming off.
[0030]
In the present embodiment, the rim detachment prevention rib 11 has a top 11a of a rib that most protrudes from the contour line S that smoothly connects the outer surface of the bead portion 4 and the sidewall portion 3 of the tire in the normal internal pressure state. An example is shown of a mountain-like shape having a slope extending smoothly from the top portion 11a to the contour line S. Further, it is desirable that the rim detachment prevention rib 11 has a top height h from the contour line S to the top portion 11a of, for example, 2 to 5 mm.
[0031]
Further, in the present invention, the length (P to C) of the flange covering area along the outer surface of the flange covering area F from the flange separation point P to the rib top point C, which is the point reaching the rib top 11a, The flange exposure length (P to D) along the rim flange Jf from the flange separation point P of the rim J to the axially outermost point D of the rim flange is set to 3 mm or more.
[0032]
In this way, by setting the length (P to C) of the flange covered area to be 3 mm or more larger than the flange exposed length (P to D), the flange covered area F is sufficient for the rim flange Jf during run-flat running. It is possible to cover the rim flange Jf so that the vicinity of the top 11a of the rib is caught by the outer point D of the rim flange Jf, thereby further preventing the rim from coming off.
[0033]
If the length (P to C) of the flange covering area is not 3 mm or more larger than the flange exposed length (P to D), the rim flange Jf is sufficiently wound and then covered so as to be caught by the flange. This prevents the effect of preventing the rim from coming off. Preferably, the length (P to C) of the flange covering area F is about 3 to 20 mm, more preferably 3 to 15 mm, and further preferably 5 to 10 mm larger than the flange exposed length (P to D).
[0034]
In the present embodiment, the flange-covered area F includes a convex curved surface portion 13 having a curvature radius R1 that protrudes outwardly of the tire, and a concave portion having a curvature radius R2 that is smoothly connected to the radially outer side of the convex curved surface portion 13. One feature is that it includes a curved surface portion 14. A concave curved surface portion 15 smoothly connected to the flange separation point P is provided inside the convex curved surface portion 13 in the tire radial direction.
[0035]
As shown in FIG. 4, the flange covering area that reaches the top of the conventional rim detachment prevention rib is composed of only a single concave curved surface portion in which the outer surface of the tire is recessed. Such a shape is rather easy to follow the rim flange. It was considered preferable. However, in this case, as shown in FIG. 5, it is easy to bend along the flange and the force to hold the rim flange is weak.
[0036]
On the other hand, the flange-covered area of the present embodiment has a convex curved surface portion 13 having a curvature radius R1 that protrudes outward from the tire, and a concave portion having a curvature radius R2 that smoothly extends radially outward from the convex curved surface portion 13. Since the curved surface portion 14 is provided, as shown in FIG. 6, the convex curved surface portion 13 reverses its curvature and covers the rim flange Jf during run-flat running so as to be caught on the rim flange Jf. The rim flange Jf is held with a stronger force, and the concave curved surface portion provided on the outer side in the radial direction acts so as to further wind the flange outer point D, so that the rim is further prevented from coming off.
[0037]
As described above, the pneumatic tire of the present embodiment uses the regular rim defined by the standard without using any specially shaped rim, and the rim detachment preventing rib is the flange-covered area F during run-flat running. As a result of firmly holding the rim flange Jf by the bending action, detachment of the rim can be effectively prevented.
[0038]
Here, it is preferable that the convex curved surface portion 13 of the flange covering area F has a radius of curvature R1 larger than a radius of curvature R2 of the concave curved surface portion, for example, a ratio of the radius of curvature (R1 / R2). For example, it is desirable to set it as 2.0-5.0, More preferably, it is 2.5-4.0.
[0039]
When the radius of curvature R1 of the convex curved surface portion 13 is smaller than the radius of curvature R2 of the concave curved surface portion 14, the holding force for holding the rim flange during the run-flat running tends to be relatively reduced. Preferably, the radius of curvature R1 is, for example, 25 mm or more in the case of a passenger car tire.
[0040]
As described above in detail, it is particularly preferable that the rim detachment prevention ribs are formed on the bead portions 4 and 4 on both sides in the tire axial direction. The shape of the rib is not limited to the illustrated example, and various shapes can be adopted.
[0041]
【Example】
The tire size was 215 / 45R16 and the pneumatic tires shown in Table 1 were prototyped (Examples 1 to 3, Comparative Examples 1 to 3, and conventional examples), and run-flat performance, wear performance, tire weight, and the like were measured. . In addition, the bead structure of an Example and a comparative example is shown in FIG. 7, and the bead structure of a prior art example is shown in FIG. 8 (the unit of a numerical value is mm).
The test method is as follows.
[0042]
<Runflat index>
The test tire is mounted on a regular rim and mounted on the four wheels of a domestic passenger car (FR car). The distance traveled around the test track with the internal pressure of 0 with the valve core removed and the vehicle is unable to run. Was measured and indexed. The larger the value, the better. In the test course, the vehicle runs on a straight line at a speed of 80 km / h and on a corner at 60 km / h. The run flat load acting on one evaluation wheel is 415 kgf.
[0043]
<Abrasion resistance>
Using the above-mentioned vehicle, the vehicle traveled approximately 3500 km on a highway and a general road at a ratio of 1: 1 under normal internal pressure, and the tire wear state was visually observed.
[0044]
<Tire weight>
The weight per tire was measured and displayed as an index with the conventional example being 100. The smaller the value, the better.
Table 1 shows the test results.
[0045]
[Table 1]

[0046]
As a result of the test, it was confirmed that the tire of the example improved the run-flat performance while using a standard rim and without significantly increasing the tire weight. In addition, it was confirmed that the smaller the ratio (L / Hc), the better the run flat performance, but the wear resistance performance is significantly impaired, so that it is not suitable for practical use. The relationship between the run flat index and the ratio (L / Hc) is shown in FIG. 9 for each test tire.
[0047]
【The invention's effect】
As described above, in the invention according to claim 1 or 3, by limiting the ratio (L / Hc) between the carcass height Hc and the radial distance L from the carcass bead point A to the carcass buttress point B. Further, it is possible to suppress slipping of the frictional contact portion on the tire cavity surface during run-flat traveling, and to prevent the carcass cord from being broken at this portion for a relatively long time.
[0048]
Further, by making the length (P to C) of the flange covering area 3 mm or more larger than the flange exposed length (P to D), the flange covering area sufficiently entrains the rim flange during run flat running, And it becomes possible to coat | cover so that the vicinity of the top part of the said rib may be caught in the outer side point D of a rim flange, and rim removal | removal can be prevented further.
[0049]
In addition, the flange-covered area is provided with a convex curved surface part and a concave curved surface part that are convex toward the outside of the tire, so that the convex curved surface part reverses the curvature during run-flat travel and covers the rim flange. The rim flange is held with a stronger force, and the concave curved surface portion provided on the outer side in the radial direction acts so as to further encircle the flange outer point D. Can be increased.
[0050]
In the invention according to claim 2, by making the curvature radius R1 of the convex curved surface portion of the flange coating area F larger than the curvature radius R2 of the concave curved surface portion, the rim detachment preventing effect can be further improved. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a pneumatic tire showing an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of a bead portion.
FIG. 3 is a cross-sectional view showing a puncture running state of a tire.
FIG. 4 is a cross-sectional view of a bead portion for explaining a conventional flange coating region.
FIG. 5 is a cross-sectional view showing the punctured state.
FIG. 6 is a cross-sectional view showing a punctured state of the tire of the present embodiment.
FIG. 7 is a diagram showing specific dimensions of an example.
FIG. 8 is a diagram showing specific dimensions of a conventional example.
FIG. 9 is a graph showing a relationship between a run flat index and a ratio (L / Hc).
[Explanation of symbols]
2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Belt layer 11 Rim detachment prevention rib J Regular rim

Claims (3)

A pneumatic tire comprising a carcass extending from a tread portion through a sidewall portion to a bead core of the bead portion, and an inner liner rubber on a tire lumen surface,
In the tire meridian section in the normal state where the tire is assembled to the regular rim and filled with the regular internal pressure and is unloaded,
A carcass height Hc that is a height from the bead base line BL to the radially outermost position of the center line of the thickness of the carcass;
From the carcass bead point A where the radial line N passing through the rim width position of the regular rim intersects the carcass centerline at the bead to the carcass buttress point B where the radial line N intersects the carcass centerline at the buttress part. The ratio (L / Hc) to the radial distance L is set to 0.30 to 0.45, and
Forming an outer surface of the bead portion and a rim detachment prevention rib protruding outward in the axial direction radially outward from a flange separation point P where the bead portion is separated from the rim flange of the regular rim;
The length (PC) along the outer surface of the flange covering area from the flange separation point P to the rib top point C, which is the top of the rim detachment prevention rib, is determined from the flange separation point P of the regular rim to the rim flange. And 3 mm or more larger than the flange exposed length (P to D) along the rim flange up to the outermost point D in the axial direction,
The pneumatic tire according to claim 1, wherein the flange covering region includes a convex curved surface portion that is convex toward the outer side of the tire and a concave curved surface portion that is smoothly connected to the radially outer side of the convex curved surface portion. 2. The pneumatic tire according to claim 1, wherein a radius of curvature R <b> 1 of the convex curved surface portion is larger than a radius of curvature R <b> 2 of the concave curved surface portion. A tire and rim assembly in which the tire according to claim 1 or 2 is assembled to the regular rim.

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