JP4634818B2 - Pneumatic run flat tire - Google Patents

Description

  The present invention relates to a side-reinforced pneumatic run-flat tire.

A run-flat tire has been devised that can run while maintaining maneuverability for a certain distance even when the tire is punctured and the internal pressure disappears. There are side-reinforced run-flat tires (see, for example, Patent Document 1 to Patent Document 3).
Japanese Patent Laid-Open No. 2-147417 Japanese Patent Laid-Open No. 3-176213 JP-A-10-67211

  However, with side-reinforced run-flat tires, the side walls are able to withstand the weight of the vehicle even when there is no internal pressure, and hard rubber is used as the side reinforcing layer to prevent the side walls from collapsing completely. In a normal use state in which the internal pressure is filled, there is a problem in that the push-up from the road surface during traveling cannot be sufficiently absorbed, and the ride comfort of the vehicle is deteriorated.

  Recent vehicles require excellent handling stability and handling responsiveness, so tires have become more flattened (for example, super-flat tires with a tire cross-section height of 80 mm or less have appeared). When such an ultra-flat tire is a side-reinforced run-flat tire, the deterioration of ride comfort is particularly remarkable.

  Further, in the ultra flat tire as described above, the radius of curvature of the tire inner shape line in the tire axial cross section tends to be small, and when a side reinforcing layer is provided, the inner liner rubber (inner liner cream) is vulcanized. There is a problem that it is difficult to manufacture because there is a strong tendency to cause a manufacturing defect such as a bowl-shaped rubber reservoir generated when a part of the rubber is compressed.

  From the viewpoint of the durability of the tire, the occurrence of inner liner Chris should be avoided, but if you try to avoid this, you will be forced to produce with particular attention to the occurrence of inner liner Chris at the time of tire production, There is also a problem that productivity is lowered, and as a result, it is difficult to provide tires at low cost.

  In view of the above facts, an object of the present invention is to improve the ride comfort and suppress the occurrence of manufacturing defects in a side-reinforced pneumatic run-flat tire.

According to the first aspect of the present invention, a pair of bead portions, a sidewall portion continuous with the bead portion, a tread portion continuous with the sidewall portions on both sides, and the pair of bead portions are disposed in a toroidal shape. And at least one layer of a carcass having a carcass main body positioned between the bead portions and a folded portion wound around a bead core of the bead portion, a belt layer disposed on the outer side in the tire radial direction of the carcass, A pneumatic run-flat tire provided with a side reinforcement layer disposed inside a carcass main body portion and configured to gradually decrease in thickness toward the crown portion and the bead portion of the carcass, and the side reinforcement The maximum thickness of the layer is 6 to 19% of the tire cross-section height, and the tire inner surface at the maximum thickness position of the side reinforcing layer in the tire axial cross-section. The radius of curvature, said tire section Ri 37 to 75% der height, outside of the gauge from the folded portion of the carcass in the maximum thickness position of the side reinforcing layer than the inner gauge than該折return part It is characterized by being large .

  Here, the reason why the lower limit of the maximum thickness of the side reinforcing layer is set to 6% of the tire cross-section height is that if it is less than this, a sufficient distance cannot be traveled at the time of puncture, and the upper limit is set to 19%. If this is exceeded, the ride comfort of the vehicle is greatly deteriorated.

  In addition, the lower limit of the radius of curvature of the tire inner surface at the maximum thickness position of the side reinforcing layer is set to 37% of the tire cross-section height because part of the inner liner is compressed by the rubber flow during tire vulcanization. This is because it is easy to form a rubber reservoir (inner liner chris), and the upper limit is set to 75% because if it exceeds this, the bending rigidity of the side reinforcing layer increases and the riding comfort deteriorates.

  In the pneumatic run flat tire according to claim 1, since the thickness of the side reinforcing layer is appropriately set, the ride strength is excellent while the run flat tire has a low flatness ratio, and the side reinforcing layer Since the radius of curvature of the tire inner surface at the maximum thickness position is set to be reasonably large, it becomes difficult to form a bowl-like rubber pool in the inner liner portion during tire vulcanization, and the occurrence of inner liner chris is suppressed.

According to a second aspect of the present invention, a pair of bead portions, a sidewall portion continuous with the bead portion, a tread portion continuous with the sidewall portions on both sides, and a space between the pair of bead portions are disposed in a toroidal shape. And at least one layer of a carcass having a carcass main body positioned between the bead portions and a folded portion wound around a bead core of the bead portion, a belt layer disposed on the outer side in the tire radial direction of the carcass, A pneumatic run flat tire provided with a side reinforcing layer disposed inside a carcass main body portion and configured to gradually decrease in thickness toward the crown portion and the bead portion of the carcass, and having a tire cross-section height Is 80 mm or less, the maximum thickness of the side reinforcing layer is 5 to 15 mm, and the maximum thickness of the side reinforcing layer in the cross section in the tire axial direction is The radius of curvature of the inner surface of the tire in the location is Ri 30 to 60mm der, in the maximum thickness position of the side reinforcing layer, outside of the gauge from the folded portion of the carcass is greater than the inner gauge than該折return part It is characterized by that.

  Here, the tire cross-section height is set to 80 mm or less in order to clarify that the tire is applied to an ultra-low flatness tire. Moreover, the reason why the lower limit of the maximum thickness of the side reinforcing layer is set to 5 mm is that if it is less than this, it is not possible to travel a sufficient distance at the time of puncture, and the upper limit is set to 15 mm. This is because the ride comfort is greatly deteriorated.

  Furthermore, the lower limit of the radius of curvature of the inner surface of the tire at the maximum thickness position of the side reinforcing layer is set to 30 mm. Below this, a part of the inner liner is compressed by rubber flow during tire vulcanization, resulting in a bowl-like shape. This is because the rubber reservoir (inner liner chris) can be easily formed, and the upper limit is set to 60 mm. If the upper limit is exceeded, the bending rigidity of the side reinforcing layer is increased and the riding comfort is deteriorated.

  In the pneumatic run flat tire according to claim 2, since the thickness of the side reinforcing layer is appropriately set, the run flat tire has a low flatness and is excellent in ride comfort. Since the radius of curvature of the tire inner surface at the maximum thickness position is set to be reasonably large, it becomes difficult to form a bowl-like rubber pool in the inner liner portion during tire vulcanization, and the occurrence of inner liner chris is suppressed.

  According to a third aspect of the present invention, in the pneumatic run-flat tire according to any one of the first and second aspects and the first aspect, the carcass includes two layers, and the carcass cord included in the carcass is a rayon. It is characterized by.

  In the pneumatic run flat tire according to claim 3, the durability of puncture traveling is improved by the rayon carcass.

The invention of claim 4 is the pneumatic run-flat tire according to any one of claims 1 to 3, wherein the outer gauge is at 8 mm (0.31 in) or more, said inner gauge 7.5 mm or less It is characterized by being.

  Here, the gauges outside and inside the carcass folded portion at the maximum thickness position of the side reinforcement layer were set in this way because the inner surface of the tire at the maximum thickness position of the side reinforcement layer It is for making it a shape which does not produce liner chris easily.

  In the pneumatic run-flat tire according to claim 4, since the outer gauge and the inner gauge are appropriately set from the folded portion of the carcass at the maximum thickness position of the side reinforcing layer, the productivity is maintained. In addition, it is possible to suppress the generation of inner liner chris during tire vulcanization. Moreover, the durability of the tire is maintained by suppressing the generation of the inner liner chris.

  More preferably, the gauge outside the folded portion of the carcass at the maximum thickness position of the side reinforcing layer is 8 mm or more, and the inner gauge is 7.5 mm or less.

  According to a fifth aspect of the present invention, in the pneumatic run flat tire according to any one of the first to fourth aspects, the folded portion extends to a position sandwiched between the belt layer and the carcass main body. It is characterized by being terminated.

  In the pneumatic run flat tire according to claim 5, since the carcass has a so-called envelope structure, the load of the carcass is increased by increasing the burden of the carcass among the loads acting near the sidewall portion during the run flat running. Can be reduced.

  Accordingly, the maximum thickness of the side reinforcing layer can be reduced, the ride comfort can be improved, and the radius of curvature of the tire inner surface at the maximum thickness position of the side reinforcing layer can be set.

  As described above, according to the pneumatic run flat tire of the present invention, in the side-reinforced pneumatic run flat tire, it is possible to improve the ride comfort and to suppress the occurrence of manufacturing defects. Has an effect.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2, a pneumatic run-flat tire 10 according to the present embodiment includes a pair of bead portions 12, sidewall portions 14 respectively connected to the bead portions 12, and the sidewall portions 14 on both sides. At least a tread portion 24, a carcass main body portion 16A disposed between the bead portions 12 between the pair of bead portions 12 and a folded portion 16B wound around the bead core 28 of the bead portion 12. The carcass 16 of one layer, the belt layer 22 disposed on the outer side in the tire radial direction of the carcass 16, and the thickness gradually decreases toward the crown portion and the bead portion 12 of the carcass 16 disposed on the inner side of the carcass main body portion 16A. And a side reinforcing layer 18 configured as described above.

  The belt layer 22 is reinforced by a belt reinforcing layer 26, and a tread 24 is provided outside the belt reinforcing layer 26 in the tire radial direction. The pair of bead portions 12 are reinforced by a chafer 32 and a bead filler 34, respectively, and an inner liner 30 is disposed on the tire inner surface 20 between the pair of bead portions 12.

  The maximum thickness A of the side reinforcing layer 18 is 6 to 19% of the tire cross-section height SH, and the radius of curvature R of the tire inner surface 20 at the maximum thickness position of the side reinforcing layer 18 in the tire axial cross section is The cross-sectional height SH is 37 to 75%.

  Here, the reason why the lower limit of the maximum thickness A of the side reinforcing layer 18 is set to 6% of the tire cross-section height SH is that if it is less than this, a sufficient distance cannot be traveled at the time of puncture, and the upper limit is 19% The reason for this is that if this is exceeded, the ride comfort of the vehicle is greatly deteriorated.

  In addition, the lower limit of the radius of curvature R of the tire inner surface 20 at the maximum thickness position of the side reinforcing layer 18 is set to 37% of the tire cross-section height SH because part of the inner liner is compressed due to rubber flow during tire vulcanization. This is because it becomes easy to form a bowl-like rubber reservoir (inner liner chris), and the upper limit is set to 75% because if it exceeds this, the bending rigidity of the side reinforcing layer increases and the riding comfort deteriorates. .

  Specifically, when the tire cross-section height SH is about 80 mm, for example, the maximum thickness A of the side reinforcing layer 18 is 5 to 15 mm. Further, the radius of curvature R of the tire inner surface 20 is 30 to 60 mm.

  The carcass 16 is composed of, for example, two layers, and a carcass cord (not shown) included in the carcass 16 is, for example, rayon. The folded portion 16B of the carcass 16 extends to a position sandwiched between the belt layer 22 and the carcass main body portion 16A and terminates. That is, the carcass 16 in the pneumatic run-flat tire 10 has a so-called envelope structure.

  The gauge B outside the folded portion 16B of the carcass 16 at the maximum thickness position of the side reinforcing layer 18 is 6 mm or more, and the gauge C inside the folded portion 16B is 12 mm or less. As shown in FIG. 2, the gauge C specifically includes the gauge of the carcass main body portion 16 </ b> A, the gauge of the side reinforcing layer 18, and the gauge of the inner liner 30.

  Here, in the maximum thickness position of the side reinforcing layer 18, when the folded portion 16B is a plurality of layers, the outer gauge B is a gauge outside the tire from the outermost layer surface of the folded portion 16B, and the inner gauge C Is a gauge inside the tire from the innermost layer surface of the folded portion 16B.

  The reason why the outer gauge B and the inner gauge C are set in this way is to make the shape of the tire inner surface 20 at the maximum thickness position of the side reinforcing layer 18 into a shape that hardly causes the inner liner chris.

More preferably, the outer gauge B is 8 mm or more, and the inner gauge C is 7.5 mm or less.
(Function)
In the pneumatic run-flat tire 10, the thickness of the side reinforcing layer 18 is set appropriately, so that it is a run-flat tire with a low flatness ratio and has excellent ride comfort, and the maximum thickness of the side reinforcing layer 18. Since the radius of curvature of the tire inner surface 20 at the position is set to be moderately large, it becomes difficult to form a bowl-like rubber reservoir in the inner liner 30 during tire vulcanization, and the occurrence of inner liner chris (manufacturing failure) is suppressed. The

  Further, since the gauge B outside the folded portion 16B of the carcass 16 and the gauge C inside the carcass 16 at the maximum thickness position of the side reinforcing layer 18 are set appropriately, the tire vulcanization can be performed while maintaining the productivity. Generation of inner liner chris can be suppressed. Further, by suppressing the generation of the inner liner chris, the tire inner surface 20 is not greatly cracked, and the durability of the tire is maintained.

  Furthermore, since the carcass 16 has a so-called envelope structure, it is possible to increase the burden on the carcass 16 and reduce the burden on the side reinforcing layer 18 among the loads acting near the sidewall portion 14 during run-flat travel.

  Therefore, the maximum thickness A of the side reinforcing layer 18 can be reduced, and the riding comfort can be improved. Further, by reducing the thickness of the side reinforcing layer 18, the radius of curvature of the outer surface of the side reinforcing layer 18 (the inner surface of the carcass 16) at the maximum thickness position of the side reinforcing layer 18 can be increased. The radius of curvature of the inner surface can be set large. As a result, the curvature radius R of the tire inner surface 20 at the maximum thickness position of the side reinforcing layer 18 can be set large, and the generation of the inner liner chris can be suppressed by setting the curvature radius R large.

When the tire cross-section height SH of the pneumatic run-flat tire 10 is, for example, an ultra-flat shape of about 80 mm, the lateral rigidity of the tire is high, so that the steering stability during high-speed cornering is excellent, and the tire outer diameter is Even in the same case, since the rim diameter is increased, a larger brake disc can be mounted, and high brake performance can be obtained. Furthermore, since the tire becomes more responsive to steering due to the low flatness, it can be crisply run by being mounted on a sports car or the like.
(Test example)
Under the conditions shown in Table 1, 50 pneumatic run-flat tires according to the conventional example, comparative example 1 and comparative example 2 were prototyped, respectively, and the inner liner chris generation rate, run-flat durability and riding comfort were tested.

  The tire sizes are all 225 / 35R19, the belt layer is two layers, steel is used for the cord, and the outer periphery of the belt layer is reinforced by the belt reinforcing layer. The carcass cord is rayon. The side reinforcing layer is disposed between the carcass and the inner liner.

  As for the structure of the carcass, the conventional example is a two-layer up-ply carcass, and the first and second embodiments have a two-layer envelope structure.

  The inner liner Chris occurrence rate in Table 1 is determined by individually checking whether or not the inner liner Chris (the ridge-like rubber pool in the inner liner) is generated for 50 prototype tires. It shows the ratio of the number of tires that generate Chris.

  Run-flat durability assumes a state where the internal pressure has been reduced to 0 due to puncture, with the air valve open, a load of 4 kN on the drum tester, and continuous running at a speed of 89 km / h (55 mi / h) The distance traveled until the failure occurred was measured. The result shown in Table 1 is an index with the conventional example as 100.

  In the ride comfort evaluation test, each tire is attached to a real vehicle, and the vehicle runs on a typical typical road surface. The passengers subjectively evaluate the various vibrations that occur at this time and the accompanying interior noise. The results are indicated by an index with the conventional example being 100. A larger value indicates a better result.

  According to this test example, the occurrence rate of the inner liner chris reached 90% in the conventional example, and most of the production was defective, but in Example 1, it was only 20%. It has not occurred.

  Regarding run-flat durability, no decrease in durability was observed in Example 1 and Example 2, and it was confirmed that both had the same durability.

  With respect to the ride comfort, the ride comfort similar to that of the conventional example was obtained in Example 1, and an improvement in ride comfort of 10% was confirmed in Example 2.

It is sectional drawing of a pneumatic run-flat tire. It is an expanded sectional view of a pneumatic run flat tire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic run-flat tire 12 Bead part 14 Side wall part 16 Carcass 16A Carcass main-body part 16B Fold-up part 18 Side reinforcement layer 20 Tire inner surface 22 Belt layer 24 Tread part 28 Bead core A Maximum side reinforcement layer thickness B Side reinforcement layer Gauge outside the carcass body at the maximum thickness position C Gauge inside the carcass body at the maximum thickness position of the side reinforcing layer R Radius of curvature of the tire inner surface at the maximum thickness position of the side reinforcing layer SH Tire cross-section height

Claims (5)

A pair of bead portions, a sidewall portion continuous to the bead portion, a tread portion continuous to the sidewall portions on both sides, and a space between the pair of bead portions disposed between the bead portions. At least one layer of a carcass having a carcass main body portion and a folded portion wound around a bead core of the bead portion, a belt layer disposed on the outer side in the tire radial direction of the carcass, and an inner portion of the carcass main body portion A pneumatic run-flat tire comprising a side reinforcing layer configured to gradually reduce the thickness toward the crown portion and the bead portion of the carcass,
The maximum thickness of the side reinforcing layer is 6 to 19% of the tire cross-sectional height,
In the tire axial section, the radius of curvature of the inner surface of the tire at the maximum thickness position of the side reinforcing layer, Ri 37 to 75% der of the tire section height,
The pneumatic run-flat tire according to claim 1 , wherein a gauge outside the folded portion of the carcass at the maximum thickness position of the side reinforcing layer is larger than a gauge inside the folded portion . A pair of bead portions, a sidewall portion continuous to the bead portion, a tread portion continuous to the sidewall portions on both sides, and a space between the pair of bead portions disposed between the bead portions. At least one layer of a carcass having a carcass main body portion and a folded portion wound around a bead core of the bead portion, a belt layer disposed on the outer side in the tire radial direction of the carcass, and an inner portion of the carcass main body portion A pneumatic run-flat tire comprising a side reinforcing layer configured to gradually reduce the thickness toward the crown portion and the bead portion of the carcass,
The tire cross-section height is 80 mm or less,
The maximum thickness of the side reinforcing layer is 5 to 15 mm,
In the tire axial section, the radius of curvature of the inner surface of the tire at the maximum thickness position of the side reinforcing layer, Ri 30 to 60mm der,
A pneumatic run flat tire characterized in that, at the maximum thickness position of the side reinforcing layer, a gauge outside the folded portion of the carcass is larger than a gauge inside the folded portion .   3. The pneumatic run-flat tire according to claim 1, wherein the carcass includes two layers, and a carcass cord included in the carcass is a rayon. The outer gauge is 8 mm or more,
The pneumatic run-flat tire according to any one of claims 1 to 3, wherein the inner gauge is 7.5 mm or less.   The pneumatic runflat according to any one of claims 1 to 4, wherein the folded portion extends to a position sandwiched between the belt layer and the carcass main body. tire.

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