JP2006130995A - Run-flat tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a run-flat tire capable of establishing the run-flat durability and high-speed durability compatibly and being embodied in a lightweight construction. <P>SOLUTION: The run-flat tire 1 is equipped with a pair of bead parts 1 including a bead core 11a and bead filler 11b, a carcass layer 12 folded back round the bead core 11a, side wall reinforcing layers 14 to reinforce side walls 20, and a bead reinforcing layer 13 folded back round the bead core 11a and structured so that organic fiber cords of the specified sort are impregnated with rubber components. The folded-back end 12a of the carcass layer 12 positioned under a first belt layer 16 is positioned on the side nearer the tire equator line CL than the belt end 16a in the tire width direction of the first belt layer 16, and the organic fiber cords are arranged at an angle of 0-45 degrees to the bead core 11a on the surface of the side wall 20. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a run flat tire comprising a crescent-shaped rubber stock in a cross section in the tire width direction and including a sidewall reinforcing layer that reinforces the sidewall, and in particular, achieves both run flat durability and high speed durability, and a tire. The present invention relates to a run-flat tire that reduces weight.

  Conventionally, it consists of a plurality of belt layers constructed by impregnating rubber components into low elastic organic fiber (for example, nylon fiber) cords, and a crescent-shaped rubber stock in the cross section in the tire width direction to reinforce the sidewall. A run flat tire including a sidewall reinforcing layer is known.

  For this run-flat tire, for example, by increasing the thickness of the sidewall reinforcement layer, the amount of deflection of the run-flat tire is controlled, and durability such as the distance that can be run in the run-flat state (so-called puncture state) Technology for improving run flat durability) is disclosed (for example, Patent Documents 1 and 2).

According to this technique, it is possible to suppress the occurrence of bursts that break the run-flat tire so as to burst due to impact on the tire, tire damage, heat generation inside the run-flat tire, or the like. Moreover, since the tread rigidity is improved by using low-elasticity organic fibers for the belt layer, high-speed durability can be ensured.
JP 48-27924 (page 1-3, FIG. 1) JP 47-62114 A (page 1-2, FIG. 1)

  However, in the run flat tire described above, there is a problem that the tire weight increases due to the thick side wall reinforcing layer and the provision of a plurality of belt layers in order to ensure run flat durability. there were.

  Further, in order to prevent an increase in tire weight, it is conceivable to reduce the number of belt layers, but high-speed durability is lowered.

  Therefore, the present invention has been made in view of such problems, and an object thereof is to provide a run flat tire that achieves both run flat durability and high speed durability and reduces the weight of the tire. .

  The first feature of the present invention is that a pair of bead parts (bead part 11) including at least a bead core (bead core 11a) and a bead filler (bead filler 11b), and a bead core from the tire width direction inner side to the tire width direction outer side. A folded carcass layer (carcass layer 12) and a side wall reinforcing layer that is disposed inside the carcass layer in the tire width direction and is made of a crescent-shaped rubber stock in a cross section in the tire width direction and that reinforces the side wall (side wall 20) (Sidewall reinforcement layer 14) is provided between the bead core and the carcass layer, and is folded back from the tire width direction inner side to the tire width direction outer side around the bead core, and a predetermined organic fiber cord is impregnated with a rubber component. An organic fiber reinforcing layer (bead reinforcing layer 13) composed of The carcass layer extends to the lower side of the belt layer (first belt layer 16) via the side wall, and is a folded portion that is an end located on the lower side of the belt layer. The end portion (folded end portion 12a) is located closer to the tire equator line (tire equator line CL) than the belt end portion (belt end portion 16a), which is the end portion of the belt layer in the tire width direction, and a predetermined organic fiber. The gist of the cord is that it is arranged so as to have an angle of 0 to 45 degrees with respect to the bead core on the side wall.

  According to such a feature, in addition to the carcass layer having an envelope structure (for example, 1 Penv), the predetermined organic fiber cord constituting the organic fiber reinforcing layer has 0 to 45 degrees with respect to the bead core. Compared to flat tires, the amount of deflection during run-flat is reduced and run-flat durability is improved. In addition, when an organic fiber cord exceeds 45 degree | times with respect to a bead core, the effect | action which reduces the deflection amount of a run flat state will decrease.

  Here, the envelope structure means that the carcass layer extends to the lower side of the belt layer via the sidewall, and the folded end portion, which is the end portion located on the lower side of the belt layer, is the tire width of the belt layer. It shows that the structure is located closer to the tire equator line than the belt end, which is the end in the direction.

  Since the carcass layer 12 has an envelope structure, it is possible to absorb impact generated when riding over a small protrusion (for example, a step) on the road surface and improve high-speed durability, ride comfort, and the like.

  In addition, the run flat tire has an envelope structure (for example, 1Penv) in addition to the carcass layer, and has an organic fiber reinforcing layer, so that the thickness of the sidewall reinforcing layer is thinner than that of a conventional run flat tire. This can reduce the weight of the tire.

  In addition, the run-flat tire can reduce the thickness of the sidewall reinforcement layer, thereby reducing the contact pressure between the shoulder side and the road surface during normal internal pressure, and suppressing the growth rate in the tire radial direction. Thus, high speed durability is improved.

  In addition, the run-flat tire can reduce the vertical spring (elasticity in the longitudinal direction of the tire) by reducing the thickness of the sidewall reinforcing layer, so the weight distribution, rigidity distribution, and dimensional distribution inside the tire. It becomes effective in the umiformity which is uniformity.

  The second feature of the present invention relates to the first feature of the present invention, and is provided on the outer side in the tire radial direction of the belt layer, and comprises at least two types of organic fiber cords having high elasticity and organic fiber cords having low elasticity. The gist is that a belt reinforcing layer (belt reinforcing layer 18) configured by impregnating a rubber component into the hybrid belt reinforcing cord is provided.

  According to such a feature, the run-flat tire has the effect of suppressing the growth rate in the tire radial direction at the normal internal pressure by using the hybrid reinforcement cord for the belt reinforcement layer, so that the high-speed durability is further improved. To do.

  Further, in some conventional run flat tires, two or more belt reinforcing layers are used. However, in the run flat tire of the present invention, it is possible to form a single layer of hybrid reinforcing cord in the belt reinforcing layer. The weight of the tire can be further reduced as compared with the run flat tire.

  A third feature of the present invention relates to the second feature of the present invention, and is a volume of a high elastic organic fiber cord constituting the hybrid belt reinforcing cord and a low elastic organic fiber cord constituting the hybrid belt reinforcing cord. The gist is that the ratio (high elastic organic fiber cord / low elastic organic fiber cord) is "2" or more.

  According to such a feature, the run-flat tire further suppresses the growth rate in the tire radial direction at normal internal pressure because the high elastic organic fiber cord / low elastic organic fiber cord is “2” or more. Since the effect is obtained, high-speed durability is improved.

  The fourth feature of the present invention relates to the first feature to the third feature of the present invention, and is summarized in that the highly elastic organic fiber cord is an aramid fiber.

  The fifth feature of the present invention relates to the fourth feature of the present invention, and is summarized in that the low-elasticity organic fiber cord is a nylon fiber.

  The sixth feature of the present invention relates to the first feature of the present invention, and the summary is that the predetermined organic fiber cord is an aramid fiber.

  The present invention may be configured as follows. That is, in the cross section in the tire width direction, the height from the bead toe (bead toe 11c) included in the bead portion to the inner end portion (inner end portion 13a) that is an end portion folded inward in the tire width direction of the organic fiber reinforcing layer. The gist of the inner height (H1) is 40% or less of the tire section height (H) which is the height from the bead toe to the outermost position of the tread portion.

  In the tire width direction cross section, the outer height (H2) that is a height from the bead to the outer end portion (13b) that is an end portion folded back to the outer side in the tire width direction of the organic fiber reinforcing layer is the tire. The summary is that it is 55% or less of the section height.

  ADVANTAGE OF THE INVENTION According to this invention, the run flat tire which makes run-flat durability and high-speed durability compatible, and aims at weight reduction of a tire can be provided.

  Next, an example of a run flat tire according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(Configuration of run-flat tire)
FIG. 1 is a partially exploded perspective view of a run flat tire 1 according to this embodiment. As shown in FIG. 1, the run-flat tire 1 has a pair of bead portions 11 including at least a bead core 11a and a bead filler 11b. Specifically, a steel cord or the like is used for the bead core 11a constituting the bead unit 11.

  The run-flat tire 1 has a carcass layer 12 that is folded from the inner side in the tire radial direction to the outer side in the tire radial direction around the bead core 11a.

  Between the bead core 11a and the carcass layer 12, a bead reinforcement layer (organic fiber reinforcement layer (not shown in FIG. 1)) folded from the tire radial inner side to the tire radial outer side is disposed around the bead core 11a. .

  A side wall reinforcing layer 14 that reinforces the side wall 20 is disposed on the inner side in the width direction of the carcass layer 12.

  An inner liner 15 that is a highly airtight rubber layer corresponding to a tube is provided inside the carcass layer 12 and the sidewall reinforcing layer 14 in the tire radial direction. A first belt layer 16 and a second belt layer 17 are disposed on the outer side of the carcass layer 12 in the tire radial direction.

  A belt reinforcing layer 18 (a layer reinforcing layer 18A and a cap reinforcing layer 18B) that reinforces the first belt layer 16 and the second belt layer 17 is disposed outside the second belt layer 17 in the tire radial direction.

  A tread portion 19 that contacts the road surface is disposed outside the belt reinforcing layer 18 in the tire radial direction.

  Next, the carcass layer 12, the bead reinforcement layer 13, the sidewall reinforcement layer 15, and the belt reinforcement layer 18 described above will be described with reference to FIG. FIG. 2 is a cross-sectional view of the run flat tire 1 in the tire width direction.

  As shown in FIG. 2, the carcass layer 12 is folded back from the inner side in the tire width direction to the outer side in the tire width direction around the bead core 11a. The carcass layer 12 has an envelope structure.

  Here, the envelope structure means that the carcass layer 12 extends to the lower side of the first belt layer 16 via the sidewall 20 and is a folded end portion 12a that is an end portion located on the lower side of the belt layer 16. However, the structure is located on the tire equator line CL side with respect to the belt end portion 16a which is the end portion of the belt layer 16 in the tire width direction.

  The bead reinforcing layer 13 is provided between the bead core 11a and the carcass layer 12 as described above, and is folded around the bead core 11a from the inner side in the tire radial direction to the outer side in the tire radial direction.

  Specifically, the bead reinforcement layer 13 is configured by impregnating a predetermined organic fiber cord with a rubber component. The predetermined organic fiber cord is preferably an aramid fiber.

  Here, as shown in FIG. 3, the bead reinforcement layer 13 is arranged on the side wall 20 so as to have an angle of 0 to 45 degrees with respect to the bead core 11 a.

  Further, in the tire width direction cross section, the inner height (H1) that is the height from the bead toe 11c included in the bead portion 11 to the inner end portion 13a that is an end portion folded back inward in the tire width direction of the bead reinforcement layer 13. ) Is preferably 40% or less of the tire section height (H) which is the height from the bead toe 11c to the outermost position of the tread portion 19.

  In the cross section in the tire width direction, the outer height (H2), which is the height from the bead toe 11c to the outer end portion 13b that is the end portion folded back to the outer side in the tire width direction of the bead reinforcement layer 13, is the tire section height. It is preferable that it is 55% or less of (H).

  As described above, the sidewall reinforcing layer 15 is disposed on the inner side in the tire radial direction of the carcass layer 12. Further, the sidewall reinforcing layer 15 is constituted by a crescent-shaped rubber stock in the cross section in the tire width direction.

  The belt reinforcing layer 18 includes a layer reinforcing layer 18A and a cap reinforcing layer 18B, and is disposed on the outer side in the tire radial direction of the second belt layer 17 as described above.

  Specifically, the belt reinforcing layer 18 is configured by impregnating a rubber component into a hybrid belt reinforcing cord composed of at least two types of a high elastic organic fiber cord and a low elastic organic fiber cord.

  Here, the volume ratio of the highly elastic organic fiber cord constituting the hybrid belt reinforcing cord to the low elastic organic fiber cord constituting the hybrid belt reinforcing cord (high elastic organic fiber cord / low elastic organic fiber cord). Is preferably “2” or more.

  The high-elasticity organic fiber cord is preferably an aramid fiber, and the low-elasticity organic fiber cord is preferably a nylon fiber.

  Next, in order to further clarify the effects of the present invention, the results of tests performed using run-flat tires according to the following comparative examples, Examples 1 and 2 will be described.

  The sizes of the run flats according to the comparative example, the example 1, and the example 2 are all “225 / 50R17”. That is, the tread width is about 225 mm, the flatness (ratio of the tire cross-section height to the tire width) is about 50%, and the rim diameter is 17 inches.

Table 1 shows the structure of the run flat according to the comparative example, Example 1 and Example 2.

  Here, 2PH indicates a high turn-up structure (H) in which the number of carcass layers (so-called ply) is 2 plies (P) and the folded portion of the carcass layer is long.

  1Penv indicates an envelope structure in which the ply is 1P and the carcass layer is described above.

  The Kevlar flipper (Kev-FL) means that the inner height (H1) of the bead reinforcement layer is 40% or less of the tire section height (H) and the outer height (H2) is the tire section. The structure which is 55% or less of height (H) is shown. That is, the inner height (H1) of the bead reinforcing layer in the example is 30% of the tire section height (H), and the outer height (H2) of the bead reinforcing layer is 48%. In addition, the bead reinforcing layer in the embodiment is disposed so as to have an angle of 45 degrees with respect to the bead core 11a on the side wall surface.

  2CAP / 2LAY indicates that the cap reinforcing layer is two layers and the layer reinforcing layer is two layers. 1CAP / LAY indicates that the cap reinforcing layer is one layer and the layer reinforcing layer is one layer.

  As shown in Table 1, in the run flat tire according to the comparative example, the structure of the carcass layer (hereinafter, ply structure) is 2PH, the side wall reinforcing layer is 10.5 mm, and the bead reinforcing layer is not provided. Further, 1 × 5 is used as the belt material, and the cord constituting the belt layer is 58 degrees with respect to the tire circumferential direction. Further, nylon is used for the cord constituting the belt reinforcing layer, and the belt reinforcing layer is 2CAP / 2LAY.

  In the run flat tire according to the first embodiment to which the present invention is applied, the PLY structure is 1Penv, the side wall reinforcing layer is 10.5 mm, and the bead reinforcing layer is Kev-FL. Further, 1 × 5 is used as the belt material, and the cord constituting the belt layer is 58 degrees with respect to the tire circumferential direction. Moreover, the hybrid belt reinforcement cord mentioned above is used for the cord which comprises a belt reinforcement layer, and a belt reinforcement layer is 1CAP / LAY.

  In the run flat tire according to Example 2 to which the present invention is applied, the PLY structure is 1 Penv, the side wall reinforcing layer is 7.0 mm, and the bead reinforcing layer is Kev-FL. Further, 1 × 5 is used as the belt material, and the cord constituting the belt layer is 58 degrees with respect to the tire circumferential direction. Further, a hybrid belt reinforcing cord is used as a cord constituting the belt reinforcing layer, and the belt reinforcing layer is 1CAP / LAY.

  Next, the weight, uniformity (RFV), run-flat durability, and high-speed durability in the run flat tires according to the above-described comparative example, Example 1 and Example 2 will be described.

Table 2 shows the test results of tire weight, uniformity (RFV), run-flat durability, and high-speed durability in the run-flat tires according to Example 1 and Example 2.

<Tire weight>
The index of tire weight 14.5 kg in the run flat tire according to the comparative example was set to “100”, and the tire weight index in the run flat tire according to Example 1 and Example 2 was measured. In addition, it shows that a tire weight is so heavy that an index | exponent is large.

  As a result, the run-flat tires according to Example 1 and Example 2 were evaluated to have a lighter tire weight (so-called reduction in tire weight) than the run-flat tires according to the comparative examples.

<Uniformity (RFV)>
Radial force variation (RFV) 107N showing variation in the tire radial direction of the run-flat tire according to Comparative Example 1 by a method specified by JASO C607 using a uniformity test apparatus in which each run-flat tire is installed indoors. Was set to “100”, and the RFV of the run-flat tire according to Example 1 and Example 2 was indexed. In addition, RFV is excellent, so that an index | exponent is small.

  As a result, the run flat tire according to Example 2 was evaluated as having excellent uniformity (RFV) as compared to the run flat tire according to the comparative example.

<Runflat durability>
The run-flat tires according to Comparative Example, Example 1 and Example 2 were rolled at a constant speed with a run-flat drum installed indoors under the condition of an internal pressure of 0 Pa (so-called run flat state) with a specified load. The index of the distance 51 km that the run-flat tire according to the comparative example can travel was set to “100”, and the run-flat distance of the run-flat tire according to Example 1 and Example 2 in the run-flat state was evaluated as a relative value. Note that the greater the index, the longer the distance that can be traveled in the run-flat state, and the better the so-called run-flat durability.

  As a result, the run flat tire according to Example 1 was evaluated as having superior uranium flat durability as compared with the run flat tire according to the comparative example.

<High speed durability>
The drum speed of each run-flat tire was increased at regular intervals on a drum installed indoors, and the speed until the run-flat tire failed was measured. The faster the speed, the better the high speed durability.

  As a result, it was evaluated that the run flat tires according to Example 1 and Example 2 were superior in high-speed durability compared to the run flat tire according to the comparative example.

(Action / Effect)
According to the run-flat tire 1 according to the present embodiment described above, the carcass layer 12 has an envelope structure, and the predetermined organic fiber cord constituting the bead reinforcement layer 13 has an angle of 0 to 45 degrees with respect to the bead core 11a. By having, the amount of deflection at the time of run flat is reduced as compared with the conventional run flat tire, and the run flat durability is improved.

  In addition, since the carcass layer 12 has an envelope structure, it is possible to absorb a shock generated when overcoming a small protrusion (for example, a step) on the road surface and improve high-speed durability, riding comfort, and the like.

  In addition, the run-flat tire 1 includes the bead reinforcement layer 13 in addition to the carcass layer 12 having an envelope structure, thereby reducing the thickness of the sidewall reinforcement layer 14 compared to a conventional run-flat tire. Thus, the weight of the tire can be reduced.

  In addition, the run-flat tire 1 can reduce the contact pressure between the shoulder side and the road surface at the time of normal internal pressure by reducing the thickness of the sidewall reinforcing layer 14 and suppress the growth rate in the tire radial direction. As a result, the high-speed durability is improved.

  In addition, since the runflat tire 1 can reduce the thickness of the sidewall reinforcing layer 14, the vertical spring (elasticity in the tire vertical direction) can be reduced. Therefore, the weight distribution, rigidity distribution, This is effective for the uniformity of the dimension distribution and the like.

  Moreover, since the run-flat tire 1 has an effect of suppressing the growth rate in the tire radial direction at normal internal pressure by using a hybrid reinforcing cord for the belt reinforcing layer 18, the high-speed durability is further improved.

  Further, in some conventional run flat tires, two or more belt reinforcing layers are used. However, in the run flat tire of the present invention, it is possible to form a single layer of hybrid reinforcing cord in the belt reinforcing layer. The weight of the tire can be further reduced as compared with the run flat tire.

  Further, the run-flat tire 1 has an effect of further suppressing the growth rate in the tire radial direction at a normal internal pressure because the high elastic organic fiber cord / low elastic organic fiber cord is “2” or more. Therefore, high-speed durability is improved.

1 is a partially exploded perspective view of a run flat tire 1 according to an embodiment of the present invention. It is sectional drawing of the tire width direction of the run flat tire 1 which concerns on embodiment of this invention. It is an expansion perspective view of the bead reinforcement layer 13 concerning the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Run flat tire, 11 ... Bead part, 11a ... Bead core, 11b ... Bead filler, 11c ... Bead toe, 12 ... Carcass layer, 12a ... Folding end part, 13 ... Bead reinforcement layer, 13a ... Inner edge part, 13b ... Outer side End part, 14 ... sidewall reinforcement layer, 15 ... inner liner, 16 ... first belt layer, 16a ... belt end part, 17 ... second belt layer, 18 ... belt reinforcement layer, 18A ... layer reinforcement layer, 18B ... cap Reinforcing layer, 19 ... tread part, 20 ... side wall

Claims (6)

A pair of bead portions including at least a bead core and a bead filler;
A carcass layer folded from the inner side in the tire width direction to the outer side in the tire width direction around the bead core;
A side wall reinforcing layer that is disposed on the inner side in the tire width direction of the carcass layer, is made of a crescent-shaped rubber stock in a cross section in the tire width direction, and reinforces the side wall;
An organic fiber that is provided between the bead core and the carcass layer and is folded around the bead core from the inner side in the tire width direction to the outer side in the tire width direction, and a predetermined organic fiber cord is impregnated with a rubber component. A reinforcing layer,
The carcass layer extends to the lower side of the belt layer via the sidewall, and the folded end portion which is an end portion located on the lower side of the belt layer is an end portion in the tire width direction of the belt layer. Is located on the tire equator side than the belt end,
The predetermined organic fiber cord is arranged so as to have an angle of 0 to 45 degrees with respect to the bead core on the side wall surface.   A belt reinforcement formed by impregnating a rubber component into a hybrid belt reinforcement cord, which is provided on the outer side in the tire radial direction of the belt layer and includes at least two types of organic fiber cords having high elasticity and organic fiber cords having low elasticity. The run-flat tire according to claim 1, further comprising a layer.   Volume ratio of the highly elastic organic fiber cord constituting the hybrid belt reinforcing cord and the low elastic organic fiber cord constituting the hybrid belt reinforcing cord (the high elastic organic fiber cord / the low elastic organic cord). The run-flat tire according to claim 2, wherein the fiber cord) is "2" or more.   The run-flat tire according to claim 2 or 3, wherein the highly elastic organic fiber cord is an aramid fiber.   The run-flat tire according to claim 2 or 3, wherein the low-elasticity organic fiber cord is a nylon fiber.   The run-flat tire according to claim 1, wherein the predetermined organic fiber cord is an aramid fiber.

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