JP2006205917A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic radial tire having required run flat durability and having reduced tire spring constant and tire weight. <P>SOLUTION: The pneumatic radial tire 10 is provided with a pair of bead parts 12; a carcass 14 riding on the bead part 12 and having a folded/returning part 13 folded/returned from an inner side of the bead part 12 to the outer side; a belt layer 22 and a tread part 24 provided at the outer side in a tire radial direction of the carcass 14; a side reinforcement rubber layer 26 of an approximate crescent-like cross section arranged at an inner side of the carcass 14. Further, non-stretching organic fiber reinforcement layers for reinforcing a tire side are provided on both sides in a tire width direction respectively. In the one side organic fiber reinforcement layer, height in a tire radial direction at the bead outside is higher than that of the other side organic fiber reinforcement layer. Further, an outer end 13U in the tire radial direction of the folded/returning part 13 extends and terminates to a tire equator CL side than an end 22E in the tire width direction of the belt layer 22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic radial tire that can be run flat.

  In recent years, the progress of passenger cars has been remarkable, and basic performances such as ride comfort and handling stability have not only improved dramatically from the previous model, but also various performances such as fashionability, fuel consumption, safety etc. have been greatly improved ing. In particular, improving safety is one of the most important items purchased by general users.

  There is puncture as a safety aspect or inconvenience of the tire. In particular, when a puncture occurs and the tire internal pressure rapidly decreases, this is a phenomenon that sometimes leads to a serious situation. Although the incidence of punctures has decreased significantly compared to previous tires, it is not completely absent.

  There are several types of run-flat tires on the market that can prevent a sudden drop in tire pressure and move to a place where the tires can be safely replaced in response to such punctures. Some are equipped with.

  Among them, a conventional rim can be used as it is in a side-reinforced run-flat tire that reinforces the tire side (see, for example, Patent Document 1). Furthermore, the run-flat travelable distance exceeds 100 km, and it is considered to be an excellent tire from the viewpoint of safety and convenience.

  By the way, it is not limited to side-reinforced run-flat tires, but considering the spread of run-flat tires to many vehicles in the world, the run-flat cruising distance is still sufficient, especially on heavy vehicles. It is hard to say that there is. It also sacrifices ride comfort.

  Here, in order to ensure the run-flat property of a heavy vehicle type, it is effective to increase the rubber gauge of the reinforcing rubber layer (side reinforcing rubber layer) that reinforces the tire side. It is also effective to increase the gauge of the side reinforcing rubber layer in order to improve the run-flat durability by preventing the bending deformation of the tire side part due to the push-up from the rim flange part.

However, if the thickness is simply increased, the spring constant in the vertical direction of the tire increases, and shock and vibration from the road surface cannot be absorbed, resulting in a rugged riding comfort. Since the input to the vehicle is increased and the vehicle durability is excessively required, reduction of the spring constant and weight reduction are major issues. Further, if the thickness is simply increased, the tire side portion becomes too hard, and side deformation hardly occurs. In addition, when assembling the tire on the rim, it is necessary to use a bar or the like and make the part of the bead part exceed the rim flange, so that the rim assembly becomes extremely difficult if the gauge of the side reinforcing rubber layer is increased in this way. This also causes a negative effect.
Japanese Patent Laid-Open No. 5-112110

  In view of the above facts, an object of the present invention is to provide a pneumatic radial tire having necessary run-flat durability and having a reduced tire spring constant and tire weight.

  The present inventor has paid attention to the fact that when a run-flat tire is mounted on a vehicle and run-flat travels, it is the tire cam on the negative camber side that causes an undesirable failure in terms of durability.

  And earnestly examined, repeated experiment, and came to complete this invention.

  The invention according to claim 1 is a pair of bead parts including a pair of bead cores and bead fillers arranged on the tire radial direction outer sides of the pair of bead cores, straddling the pair of bead parts, and the bead part. A carcass having a folded portion folded from the inside to the outside, a sidewall portion disposed outside the carcass, a belt layer and a tread portion sequentially disposed on the outer side in the tire radial direction of the carcass, and the carcass A non-stretchable organic fiber having an angle with respect to a tire radial direction in a range of 45 ° to 90 ° in a pneumatic radial tire having a side reinforcing rubber layer having a substantially crescent-shaped cross section disposed inside An organic fiber reinforcement layer that has a reinforcing cord and reinforces the tire side is on one side in the tire width direction where the contact pressure with the road surface increases due to the camber angle. Provided at least on one side, the tire radial height of the organic fiber reinforcing layer on the outside of the bead is set higher than the other side in the tire width direction, and the tire radial direction of the folded portion of the carcass The outer end portion extends to the tire equator side from the end portion in the tire width direction of the belt layer.

  When the sidewall portion is deformed, tension is always applied to the sidewall portion on one side in the tire width direction. For this reason, when said organic fiber reinforcement layer provided as a side reinforcement layer has a cord, it is preferred that this cord is highly elastic. Here, the organic fiber reinforced cord is highly elastic. Thereby, even if the gauge of the organic fiber reinforcing layer is thinned, it is possible to ensure the same run-flat durability. As the fiber constituting the organic fiber reinforced cord, an aramid fiber is suitable.

  Moreover, the effect which suppresses the deformation | transformation at the time of puncture can be heightened by making this organic fiber reinforcement cord cross-position at least 45 degrees or more with respect to a carcass cord. Here, in the pneumatic radial tire, the direction of the carcass cord at the arrangement position of the organic fiber reinforcing layer is substantially the same as the tire radial direction, and therefore the angle formed by the organic fiber reinforcing cord with respect to the tire radial direction is 45 ° to 90 °. By making it within range, this is achieved.

  By providing this organic fiber reinforcing layer, the side reinforcing rubber layer can be made thinner than when not provided. Therefore, the tire weight and the tire spring constant (longitudinal spring constant) are reduced.

  In the invention according to claim 1, the height of the organic fiber reinforcing layer in the tire radial direction is higher on one side in the tire width direction than on the other side in the tire width direction. Therefore, the tire spring constant on the other side in the tire width direction can be made lower than that on the one side in the tire width direction.

  Furthermore, in the invention described in claim 1, at least one side in the tire width direction, the outer end portion in the tire radial direction of the folded portion of the carcass extends further to the tire equator side than the end portion in the tire width direction of the belt layer. It is terminated. Therefore, the gauge of the side reinforcing rubber layer can be further reduced on at least one side in the tire width direction, and the tire weight and spring constant can be further reduced.

  As described above, the invention according to claim 1 can realize a pneumatic radial tire that has the required run-flat durability and that has reduced tire spring constant and tire weight and improved performance such as riding comfort. .

  The invention according to claim 2 is characterized in that the organic fiber reinforcing layer is folded from the inside of the bead to the outside of the bead so as to wrap at least the bead core, and the tire radial height of the organic fiber reinforcing layer is the tire section height inside the bead. It is characterized by being in the range of 20 to 40% of the tire section height, and in the range of 40 to 70% of the tire section height outside the bead.

  Thus, by arranging the organic fiber reinforcing layer so as to wrap at least the bead core, even if the gauge of the side reinforcing rubber layer is thinned, it is easy to ensure equivalent run-flat durability.

  The portion of the organic fiber reinforced layer where the tension is applied is in the range of about 40% or less of the section height inside the bead, and even if an organic fiber reinforced layer is provided higher than this height, there is no problem in durability, but the tire weight It is not preferable because of the increase. In addition, if the height in the tire radial direction of the organic fiber reinforcing layer is less than 20% of the tire section height, it is difficult to apply tension to the organic fiber reinforcing cord, and the effect cannot be expected so much.

  Similar to the inside of the bead, tension is applied to the organic fiber reinforcing layer on the outside of the bead, but the range of the organic fiber reinforcing layer in which the tension is generated is in the range of 40 to 70% with respect to the section height, which is higher than the inside of the bead The range is more effective.

  According to the invention described in claim 2, the effect obtained by the invention described in claim 1 becomes more remarkable.

  The invention according to claim 3 is characterized in that the cross-sectional gauge of the side reinforcing rubber layer is thicker by 2 mm or more on the one side than on the other side.

  When running with tires mounted on a vehicle, the negative camber side has a higher contact pressure with the road surface than the anti-negative camber side, and the applied external force and the resulting deformation are large. For this reason, when the run flat durability test is carried out, it is on the negative camber side that a failure point occurs. Therefore, there is no problem even if the side reinforcing rubber layer on the anti-negative camber side, that is, the other side in the tire width direction is made thinner. The gauge difference at this time is preferably about 2 mm. If the gauge difference is too thin, the failure location may move to the anti-negative camber side and may be lowered to the durability level. By thinning the side reinforcing rubber layer on the anti-negative camber side, the longitudinal spring constant of the tire can be lowered, so that the riding comfort can be improved and the tire weight can be further reduced. .

  In the invention according to claim 4, the outer end portion in the tire radial direction of the folded portion extends to the tire equator side from the end portion in the tire width direction of the belt layer only on the one side and terminates. It is characterized by.

  By attaching to the vehicle such that the one side in the tire width direction is the negative camber side and the other side is the anti-negative camber side, the negative camber side can be reinforced more than the anti-negative camber side. That is, on the anti-negative camber side, it is not necessary to reinforce as much as the negative camber side, so the outer end in the tire radial direction of the folded portion of the carcass does not have to reach the belt layer (for example, the tire diameter that becomes the maximum tire width It may be in the direction height position). Thereby, the tire weight and the longitudinal spring constant can be further reduced on the other side in the tire width direction.

  The invention according to claim 5 is characterized in that the organic fiber reinforcing layer is provided only on the one side.

  Thereby, reduction of a tire weight and a longitudinal spring constant can be made more remarkable in the other side of a tire width direction.

  ADVANTAGE OF THE INVENTION According to this invention, while having required run-flat durability, the pneumatic radial tire with which the tire spring constant and the tire weight were reduced can be implement | achieved.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. In the second and subsequent embodiments, the same components as those already described are denoted by the same reference numerals and description thereof is omitted.

[First Embodiment]
First, the first embodiment will be described. As shown in FIG. 1, the pneumatic radial tire 10 according to the present embodiment includes a pair of bead portions 12 and a folded portion 13 that extends over the pair of bead portions 12 and is folded from the inside to the outside of the bead portion 12. And a carcass 14. Each bead portion 12 includes a bead filler 18 disposed on the outer side in the tire radial direction of the bead core 11.

  Further, the pneumatic radial tire 10 includes a sidewall portion 20 disposed on the outer side of the carcass 14, a belt layer 22 and a tread portion 24 sequentially disposed on the outer side in the tire radial direction of the carcass (the tread side), and the carcass 14. And a side reinforcing rubber layer 26 having a substantially crescent-shaped cross section disposed inside the tire.

  The carcass 14 terminates on both sides in the tire width direction, with the tire radial direction outer end 13U of the folded portion 13 extending to the tire equator CL side from the tire width direction end 22E of the belt layer 22.

  Further, the pneumatic radial tire 10 is provided with organic fiber reinforcing layers 28i and 28o for reinforcing the tire side on one side and the other side in the tire width direction, respectively. Here, when the tire is mounted, one side in the tire width direction is a negative camber side, and the other side in the tire width direction is an anti-negative camber side.

  As shown in FIG. 2, each of the organic fiber reinforcing layers 28i and 28o is a non-stretchable organic fiber reinforcing cord in which an angle θ formed with respect to the tire radial direction D is within a range of 45 ° to 90 °. 30 in an array. The height positions of the organic fiber reinforcing layers 28i and 28o in the tire radial direction are higher on the outer side of the bead than on the inner side of the bead part.

  The organic fiber reinforcing layer 28 is folded back from the inside of the bead to the outside of the bead so as to wrap the bead core 11, so that even if the gauge of the side reinforcing rubber layer 26 is thinned, it is easy to ensure run-flat durability. It has a structure.

  Further, inside the bead, the tire radial height Li of the organic fiber reinforcing layer 28i and the tire radial height Lo of the organic fiber reinforcing layer 28o are both within a range of 20 to 40% of the tire section height SH. ing. On the outside of the bead, the tire radial height Hi of the organic fiber reinforcing layer 28i and the tire radial height Ho of the organic fiber reinforcing layer 28o are both in the range of 40 to 70% of the tire section height. Further, the tire radial height Hi is higher than the tire radial height Ho.

  Thus, in this embodiment, since the organic fiber reinforcement layer 28 has the organic fiber reinforcement cord 30, even if the gauge of the side reinforcement rubber layer 26 is thinned, the side having a normal gauge thickness without the organic fiber reinforcement cord. It is possible to ensure run flat durability equal to or greater than that of the reinforcing layer. Therefore, the amount of the organic fiber reinforcing layer 28 and the side reinforcing rubber layer 26 can be reduced to the minimum necessary. Thereby, since the tire weight and the tire spring constant (longitudinal spring constant) are significantly reduced, it is possible to obtain the pneumatic radial tire 10 with improved run-flat durability and improved performance such as riding comfort.

  Moreover, the effect which suppresses the deformation | transformation at the time of puncture can be heightened by making this organic fiber reinforcement cord 30 into the direction where a carcass cord is arrange | positioned, ie, crossing arrangement | positioning at least 45 degrees or more with respect to a tire radial direction. .

  Furthermore, in this embodiment, the tire radial direction height Ho of the organic fiber reinforcing layer 28o is lower than the tire radial direction height Hi of the organic fiber reinforcing layer 28i. Therefore, the tire spring constant on the anti-negative camber side can be made lower than that on the negative camber side, and performance such as riding comfort can be further improved.

  Furthermore, in the present embodiment, on both sides in the tire width direction, the outer ends in the tire radial direction of the carcass folded portions extend to the CL side from the end in the tire width direction of the belt layer and terminate. Therefore, the gauge of the side reinforcing rubber layer 26 can be further reduced on both sides in the tire width direction, and the tire weight and spring constant are further reduced.

  Further, inside the bead, the tire radial height Li of the organic fiber reinforcing layer 28i and the tire radial height Lo of the organic fiber reinforcing layer 28o are both within a range of 20 to 40% of the tire section height SH. On the outside of the bead, the tire radial height Hi of the organic fiber reinforcing layer 28i and the tire radial height Ho of the organic fiber reinforcing layer 28o are both in the range of 40 to 70% of the tire section height. . Thereby, since the organic fiber reinforcement layer 28 is provided without waste, the tire weight and cost are reduced.

[Second Embodiment]
Next, a second embodiment will be described. As shown in FIG. 3, in the pneumatic radial tire 40 according to the present embodiment, the side reinforcing rubber layer 26i on the negative camber side (one side in the tire width direction) has an anti-negative camber side (the other side in the tire width direction). Compared to the side reinforcing rubber layer 26o, the sectional gauge is 2 mm or more thicker.

  As a result, the tire longitudinal spring constant on the anti-negative camber side can be lowered, so that the riding comfort can be improved and the tire weight can be further reduced.

[Third Embodiment]
Next, a third embodiment will be described. As shown in FIG. 4, in the pneumatic radial tire 50 according to the present embodiment, the tire width direction outer end portion 13iU of the folded portion 13i on one side (negative camber side) in the tire width direction is the tire width of the belt layer 22. It extends to the tire equator CL side from the direction end 22E and terminates. On the anti-negative camber side (the other side in the tire width direction) that does not need to be reinforced as the negative camber side, the outer end portion 13oU in the tire radial direction of the folded portion 13o is located in the vicinity of the tire maximum width portion 52. Accordingly, the length Wi of the folded portion 13i is longer than the length Wo of the folded portion 13o.

  According to this embodiment, the tire weight and the longitudinal spring constant can be further reduced on the other side in the tire width direction.

[Fourth Embodiment]
Next, a fourth embodiment will be described. As shown in FIG. 5, in the pneumatic radial tire 60 according to the present embodiment, the organic fiber reinforcing layer 58i is provided only on the negative camber side (one side in the tire width direction), and the anti-negative camber side (in the tire width direction). The organic fiber reinforcing layer is not provided on the other side.

  Thereby, reduction of a tire weight and a longitudinal spring constant can be made more remarkable on the anti-negative camber side.

<Test example>
In order to confirm the effect of the present invention, the inventor has an example of a pneumatic radial tire 10 according to the first embodiment (hereinafter referred to as Example 1) and an example of the pneumatic radial tire 10 according to the second embodiment ( Hereinafter, referred to as Example 2), an example of the pneumatic radial tire 10 according to the third embodiment (hereinafter referred to as Example 3), and an example of the pneumatic radial tire 10 according to the fourth embodiment (hereinafter referred to as Example 4). ) And an example of a pneumatic radial tire of a conventional example (hereinafter referred to as a conventional example, see the pneumatic radial tire 80 shown in FIG. 6), and performance evaluation was performed. In the pneumatic radial tire 80, the organic fiber reinforcing layer is not provided as compared with the first embodiment, and the thickness of the side reinforcing rubber layer 86 is 1 mm thick on both sides in the tire width direction.

  In this test example, all tire sizes are 225 / 45R17.

  Table 1 shows the conditions of each tire in this test example. In Table 1, “the thickness of the side reinforcing rubber layer” is the maximum thickness of the side reinforcing rubber layer.

  Further, in this test example, all tires were tested with normal internal pressure after being incorporated into a standard rim. Here, “regular internal pressure” refers to the maximum load and the air pressure corresponding to the maximum load in the applicable size / ply rating defined in the 2004 version of YEAR BOOK issued by JATMA.

  In this test example, performance evaluation was performed on three items: (1) tire weight, (2) run-flat durability, and (3) spring constant.

  In performing the performance evaluation, the tire weight was obtained by actual measurement. The lower the weight, the better. For run-flat durability and spring constant, the evaluation of the conventional tire was set to an index of 100, and the index for relative evaluation was calculated for the other tires. As for the run-flat durability, the larger the index, the better the durability, and the smaller the spring constant, the better the riding comfort.

  These evaluation results are also shown in Table 1. As can be seen from Table 1, in Examples 1, 3, and 4, all of (1) to (3) were better than the conventional examples. In Example 2, the run-flat durability was the same as the conventional one, but the tire weight and spring constant were better than the conventional example. In particular, the tire weight was better than the other examples.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. Needless to say, the scope of rights of the present invention is not limited to the above embodiment.

1 is a tire radial direction cross-sectional view of a pneumatic radial tire according to a first embodiment. It is a schematic diagram which shows the angle which the organic fiber reinforcement cord which comprises an organic fiber reinforcement layer makes with respect to a tire radial direction in the pneumatic radial tire which concerns on 1st Embodiment. It is a tire radial direction sectional view of a pneumatic radial tire concerning a 2nd embodiment. It is a tire radial direction sectional view of a pneumatic radial tire concerning a 3rd embodiment. It is a tire radial direction sectional view of a pneumatic radial tire concerning a 4th embodiment. It is tire radial direction sectional drawing of the pneumatic radial tire of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic radial tire 11 Bead core 12 Bead part 13 Fold-up part 13iU Tire radial direction outer end part 13oU Tire radial direction outer end part 13U Tire radial direction outer end part 14 Carcass 20 Side wall part 22 Belt layer 22E Tire width direction end part 24 Tread portion 26 Side reinforcement rubber layer 26i Side reinforcement rubber layer 26o Side reinforcement rubber layer 26 Organic fiber reinforcement layer 28i Organic fiber reinforcement layer 28o Organic fiber reinforcement layer 30 Organic fiber reinforcement cord 40 Pneumatic radial tire 50 Pneumatic radial tire 58i Organic fiber Reinforcement layer 60 Pneumatic radial tire

Claims (5)

A pair of bead cores, and a pair of bead portions each including a bead filler disposed on the outer side in the tire radial direction of the pair of bead cores;
A carcass having a folded portion that is folded back from the inside of the bead portion over the pair of bead portions;
A sidewall portion disposed outside the carcass;
A belt layer and a tread portion sequentially arranged on the outer side in the tire radial direction of the carcass;
A side-reinforcing rubber layer having a substantially crescent-shaped cross section disposed inside the carcass;
In a pneumatic radial tire having
An organic fiber reinforcing layer that has a non-stretchable organic fiber reinforcing cord whose angle with respect to the tire radial direction is within a range of 45 ° to 90 ° and reinforces the tire side is in contact with the road surface by a camber angle. Provided at least on one side in the tire width direction where the pressure increases,
On the one side, the tire radial direction height of the organic fiber reinforcing layer on the outside of the bead is set higher than that on the other side in the tire width direction, and the tire radial direction outer end of the folded portion of the carcass is A pneumatic radial tire characterized in that it extends to the tire equator side from the end of the belt layer in the tire width direction. The organic fiber reinforcing layer is folded from the inside of the bead to the outside of the bead so as to wrap at least the bead core,
The tire radial height of the organic fiber reinforcing layer is in the range of 20 to 40% of the tire section height inside the bead, and in the range of 40 to 70% of the tire section height outside the bead. The pneumatic radial tire according to claim 1.   3. The pneumatic radial tire according to claim 1, wherein a cross-sectional gauge of the side reinforcing rubber layer is thicker by 2 mm or more on the one side than on the other side.   The tire radial direction outer side edge part of the said folding | returning part extends to the tire equator side rather than the tire width direction edge part of the said belt layer only on the said one side, The termination | terminus is characterized by the above-mentioned. The pneumatic radial tire according to any one of the above.   The pneumatic radial tire according to any one of claims 1 to 4, wherein the organic fiber reinforcing layer is provided only on the one side.

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