JP2006264492A - Pneumatic run-flat tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a side reinforcement type pneumatic run-flat tire capable of enhancing the ride quality during the regular use by reducing the gage of a side reinforcing layer while ensuring the run-flat performance. <P>SOLUTION: A side reinforcing layer 24 has, for example, four-layered reinforcing elements 24A, 24B, 24C, 24D, and the hardness of each reinforcing element and the ratio of each reinforcing element occupying in the volume of the side reinforcing layer are adequately set. Thus, the longitudinal spring is increased in the run-flat traveling mode, and the load bearing characteristic (the run-flat performance) is high, and a large deformation of a tire is suppressed. Further, in the regular traveling mode, the longitudinal spring is small, and the ride quality is excellent. By reducing the gage of the side reinforcing layer, the weight of the tire is reduced, the vulcanizing time is shortened, and the tire uniformity is enhanced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic run-flat tire that can continue running even when an internal pressure is extremely reduced.

A type of run-flat tire that allows the vehicle to continue running when the tire is punctured and the internal pressure is reduced to 0, and the side reinforcement rubber has a substantially crescent-shaped side reinforcing rubber. (For example, refer to Patent Document 1).
JP-A-6-191243

  However, as in the conventional example described above, a side reinforcing type run flat tire has a high vertical spring (spring constant in the tire radial direction) due to the presence of a hard side reinforcing layer, and is normally filled with sufficient internal pressure. There is a fatal problem that the ride comfort is bad. Since a high vertical spring is required only during run-flat driving, it is desirable to reduce the adverse effects on the ride comfort of the side reinforcement layer as much as possible during normal use. There was a trade-off, and it was difficult to achieve both.

  In consideration of the above facts, the present invention aims to improve the ride comfort during normal use by reducing the gauge of the side reinforcing layer while ensuring the run flat performance in the side reinforcing type pneumatic run flat tire. And

  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 a carcass having a carcass body located between the bead parts and a folded part wound around the bead core of the bead part from the inside to the outside, and the thickness gradually decreases toward the bead part and the tread part. Thus, a pneumatic run-flat tire provided with a side reinforcing layer disposed on the inner surface side of the sidewall portion, wherein the side reinforcing layer has a thickness toward the bead portion and the tread portion, respectively. It has a plurality of layers of reinforcing elements that gradually decrease and have different JIS hardness, and the JIS hardness of each of the reinforcing elements is in order from the bead part side to the tread part side. Kuna' and each said volume of the reinforcement elements of is characterized in that it successively increases from the bead portion side toward the tread portion side.

  Here, the JIS hardness is a hardness measured using a type A tester in a durometer hardness test according to JIS K6253.

  In the pneumatic run-flat tire according to claim 1, the side reinforcing layer has a plurality of reinforcing elements whose JIS hardness decreases in order from the bead part side to the tread part side, and the volume of the reinforcing element is Since the size increases in order from the bead portion side toward the tread portion side, the influence of the side reinforcing layer on the ride comfort of the vehicle during normal running can be reduced and the ride comfort can be improved.

  Specifically, when the internal pressure is extremely lowered or becomes 0 due to puncture or the like, since the large deformation of the bead portion is suppressed by the reinforcing element having the highest JIS hardness, the run flat performance is also ensured. . For this reason, at the time of run-flat running, the longitudinal spring is increased by the high-strength reinforcing element present on the bead portion side, and large deformation of the tire is suppressed, so that load resistance (run-flat performance) is improved. Further, during normal running with the internal pressure filled, there is a reinforcing element having a low hardness and a large volume on the tread portion side, so that the vertical spring becomes small and the riding comfort is improved.

  Furthermore, by configuring the side reinforcing layer as described above, the gauge of the side reinforcing layer can be thinned. By thinning the gauge, the tire is reduced in weight and the vulcanization time is shortened. Uniformity is improved.

  The invention according to claim 2 is the pneumatic run-flat tire according to claim 1, wherein the JIS hardness of the reinforcing element is 55 ° to 99 °, respectively.

  Here, the reason why the range of JIS hardness is 55 ° to 99 ° is that when it falls below 55 °, the ride comfort is further improved, but the hardness is too low and the run-flat performance is inferior. It is because the danger of a crack will increase when exceeding.

  In the pneumatic run flat tire according to claim 2, since the range of the JIS hardness for the reinforcing element is appropriately set, from the low hardness reinforcing element to be arranged on the tread portion side for improving riding comfort, Reinforcing elements having an appropriate hardness can be arranged in each part of the side reinforcing layer up to a reinforcing element having a high hardness to be arranged on the bead portion side in order to ensure the run-flat performance.

  According to a third aspect of the present invention, in the pneumatic run-flat tire according to the first aspect, the side reinforcing layer includes two reinforcing elements, and the JIS hardness of each of the reinforcing elements is equal to the tread portion. The side is 55 ° to 85 °, the bead portion side is 80 ° to 99 °, and the proportion of each reinforcing element in the volume of the side reinforcing layer is 65 ± 10% on the tread portion side and 35 on the bead portion side. It is characterized by ± 5%.

  Here, the reason why the JIS hardness of the reinforcing element is set in this way is to ensure flexibility during normal running. The ratio of each reinforcing element to the volume of the side reinforcing layer is set in this way mainly to improve the load resistance when the internal pressure is reduced.

  In the pneumatic run-flat tire according to claim 3, the side reinforcing layer is constituted by two reinforcing elements, and the hardness of each reinforcing element and the proportion of the volume occupied by each reinforcing element in the volume of the side reinforcing layer are appropriately set. Therefore, ride comfort can be improved while ensuring run-flat performance.

  According to a fourth aspect of the present invention, in the pneumatic run-flat tire according to the first aspect, the side reinforcing layer is composed of three reinforcing elements, and the JIS hardness of each reinforcing element is the tread portion. In order from the side toward the bead portion side, they are 55 ° to 85 °, 75 ° to 95 °, 80 ° to 99 °, and the proportion of each reinforcing element in the volume of the side reinforcing layer is the tread portion. In order from the side toward the bead portion side, 35 ± 10%, 35 ± 10%, and 30 ± 5%.

  Here, the reason why the JIS hardness of the reinforcing element is set in this way is to achieve stepwise stress dispersion during normal running. The reason why the ratio of each reinforcing element to the volume of the side reinforcing layer is set in this manner is mainly for the purpose of gradual load sharing when the internal pressure is reduced.

  In the pneumatic run-flat tire according to claim 4, the side reinforcing layer is constituted by three reinforcing elements, and the hardness of each reinforcing element and the ratio of each reinforcing element to the volume of the side reinforcing layer are set appropriately. Therefore, the difference in hardness between the reinforcing elements can be reduced, and the ride comfort can be improved while ensuring the run-flat performance.

  According to a fifth aspect of the present invention, in the pneumatic run-flat tire according to the first aspect, the side reinforcing layer is composed of four reinforcing elements, and the JIS hardness of each reinforcing element is the tread portion. In order from the side toward the bead portion side, the reinforcing elements are 55 ° to 85 °, 60 ° to 90 °, 75 ° to 95 °, 80 ° to 99 °, and occupy the volume of the side reinforcing layer. The ratio is 35 ± 10%, 25 ± 5%, 20 ± 10%, and 20 ± 5% in order from the tread portion side to the bead portion side.

  Here, the reason why the JIS hardness of the reinforcing element is set in this way is to achieve smooth stress distribution during normal running with the minimum gauge. The reason why the ratio of each reinforcing element to the volume of the side reinforcing layer is set in this way is to achieve a smooth load sharing when the internal pressure is reduced with the minimum gauge.

  In the pneumatic run-flat tire according to claim 5, the side reinforcing layer is composed of four reinforcing elements, and the hardness of each reinforcing element and the ratio of each reinforcing element to the volume of the side reinforcing layer are set appropriately. Therefore, the difference in hardness between the reinforcing elements can be further reduced, and the ride comfort can be improved while ensuring the run-flat performance.

  As described above, according to the pneumatic run-flat tire of the present invention, in the side-reinforced type pneumatic run-flat tire, the gauge of the side reinforcement layer is made thin while ensuring the run-flat performance, so It has an excellent effect that it can improve comfort.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
In FIG. 1, a pneumatic run flat tire 10 according to the present embodiment includes a pair of bead portions 12, sidewall portions 14 that are continuous with the bead portions 12, and tread portions 16 that are continuous with the sidewall portions 14 on both sides. And a carcass main body portion 18A disposed between the bead portions 12 between the pair of bead portions 12 and a folded portion 18B wound around the bead core 22 of the bead portion 12 from the inside to the outside. A carcass 18 and a side reinforcing layer 24 disposed on the inner surface side of the sidewall portion 14 so as to gradually decrease the thickness toward the bead portion 12 and the tread portion 16 are provided.

  The pneumatic run-flat tire 10 has a belt layer 26 on the outer side in the tire radial direction of the carcass main body 18A, for example, and further has a belt reinforcing layer 28 on the outer side, like a general pneumatic tire. An inner liner 32 is disposed on the inner surface of the tire over the bead portion 12. For example, a down ply carcass 34 is disposed outside the carcass 18, and a bead filler 36 is disposed outside the bead core 22 in the tire radial direction of the bead portion 12.

  The side reinforcing layer 24 is disposed, for example, on the tire inner side of the carcass main body portion 18A, and the thickness gradually decreases toward the bead portion 12 and the tread portion 16, respectively. For example, the end portion on the tread portion 16 side is the tire inner surface side. For example, two layers of reinforcing elements 24A and 24D are terminated. Each JIS hardness is 55 ° to 85 ° for the reinforcing element 24A and 80 ° to 99 ° for the reinforcing element 24D, and increases in order from the tread portion 16 side to the bead portion 12 side (from the bead portion 12 side to the tread portion). It is desirable that the values are lowered in order toward the 16 side.

  The reason why the JIS hardness of the reinforcing elements 24A and 24D is set in this way is to ensure flexibility during normal traveling.

  The proportion of the reinforcing element 24A in the volume of the side reinforcing layer 24 is, for example, 65 ± 10%, and the proportion of the reinforcing element 24D is, for example, 35 ± 5%.

The reason why the ratios of the reinforcing elements 24A and 24D to the volume of the side reinforcing layer 24 are set in this way is mainly to improve the load resistance when the internal pressure is reduced.
(Function)
In the pneumatic run-flat tire 10, the side reinforcing layer 24 is composed of two reinforcing elements 24A and 24D, the hardness of the reinforcing element 24D on the bead portion 12 side is increased, and the hardness of the reinforcing element 24A on the tread portion 16 side is increased. Therefore, it is possible to reduce the gauge of the side reinforcing layer 24 while ensuring the run-flat performance, and to improve the riding comfort during normal use.

  Specifically, during the run-flat running, the reinforcing element 24D having a relatively high hardness in the side reinforcing layer 24 is in a state of mainly supporting the vehicle weight, so that the longitudinal spring becomes large. For this reason, the pneumatic run-flat tire 10 can withstand the load during the run-flat running, and large deformation of the tire is suppressed. Further, since the reinforcing element 24A having a relatively low hardness is arranged on the tread portion 16 side, the influence of the reinforcing element 24D having a high hardness on the riding comfort during normal running can be reduced, and the vertical spring becomes small. Ride comfort is improved.

Further, in the pneumatic run flat tire 10, the gauge of the side reinforcing layer 24 can be made thin, so that the tire is reduced in weight, the vulcanization time in the manufacturing process is shortened, and the uniformity is improved.
[Second Embodiment]
In FIG. 2, in the pneumatic run flat tire 20 according to the present embodiment, the side reinforcing layer 24 gradually decreases in thickness toward the bead portion 12 and the tread portion 16, and for example, the end portion on the tread portion 16 side is the tire. For example, three layers of reinforcing elements 24A, 24C, and 24D, each terminating on the inner surface side, are provided. Each JIS hardness is 55 ° to 85 ° for the reinforcing element 24A, 75 ° to 95 ° for the reinforcing element 24B, and 80 ° to 99 ° for the reinforcing element 24D, and is directed from the tread portion 16 side to the bead portion 12 side. It is desirable to increase the height in order (from the bead portion 12 side toward the tread portion 16 side in order).

  The reason why the JIS hardness of the reinforcing elements 24A, 24C, and 24D is set in this way is to achieve stepwise stress dispersion during normal running.

  The proportion of the reinforcing element 24A in the volume of the side reinforcing layer 24 is, for example, 35 ± 10%, the proportion of the reinforcing element 24C is, for example, 35 ± 10%, and the proportion of the reinforcing element 24D is, for example, 30 ± 5%.

  The reason why the ratios of the reinforcing elements 24A, 24C, and 24D occupying the volume of the side reinforcing layer 24 are set in this way is mainly to achieve stepwise load sharing when the internal pressure is reduced.

Since other parts are the same as those in the first embodiment, the same parts are denoted by the same reference numerals in the drawings, and description thereof is omitted.
(Function)
In the pneumatic run-flat tire 20, the side reinforcing layer 24 is composed of three reinforcing elements 24A, 24C, and 24D, the reinforcing element 24D on the bead portion 12 side has the highest hardness, and the reinforcing element on the tread portion 16 side. Since the hardness of 24A is the lowest, it is possible to reduce the gauge of the side reinforcing layer 24 while ensuring the run-flat performance, and to improve the riding comfort during normal use.

  Specifically, during run-flat travel, the stiffening element 24D having the highest hardness of the side reinforcing layers 24 is in a state of mainly supporting the vehicle weight, so that the longitudinal spring becomes large. For this reason, the pneumatic run-flat tire 20 can withstand the load during run-flat travel, and large deformation of the tire is suppressed. Further, since the reinforcing elements 24A and 24C having relatively low hardness and large volume are disposed on the tread portion 16 side, the influence of the reinforcing element 24D having high hardness on the riding comfort during normal running can be reduced, and the vertical The spring becomes smaller and the ride comfort is better. This effect is largely due to the reinforcement element 24A having a lower hardness and a larger volume among the reinforcement elements 24A and 24C.

In addition, since the difference in hardness between the reinforcing elements can be reduced, failure between the reinforcing elements is unlikely to occur.
[Third Embodiment]
In FIG. 3, in the pneumatic run flat tire 30 according to the present embodiment, the side reinforcing layer 24 gradually decreases in thickness toward the bead portion 12 and the tread portion 16, and for example, the end portion on the tread portion 16 side is the tire. For example, four layers of reinforcing elements 24A, 24B, 24C, and 24D, each terminating on the inner surface side, are provided. Each JIS hardness is 55 ° to 85 ° for the reinforcing element 24A, 60 ° to 90 ° for the reinforcing element 24B, 75 ° to 95 ° for the reinforcing element 24C, and 80 ° to 99 ° for the reinforcing element 24D. It is desirable that the height is increased sequentially from the portion 16 side toward the bead portion 12 side (lower in order from the bead portion 12 side toward the tread portion 16 side).

  The reason why the JIS hardness of the reinforcing elements 24A, 24C, and 24D is set in this way is to achieve smooth stress distribution during normal running with the minimum gauge.

  The proportion of the reinforcing element 24A in the volume of the side reinforcing layer 24 is, for example, 35 ± 10%, the proportion of the reinforcing element 24B is, for example, 25 ± 5%, and the proportion of the reinforcing element 24C is, for example, 20 ± 10%. The proportion of the reinforcing element 24D is, for example, 20 ± 5%.

  The reason why the ratios of the reinforcing elements 24A, 24B, 24C, 24D occupying the volume of the side reinforcing layer 24 are set in this manner is to achieve a smooth load sharing during normal running with the minimum gauge.

Since other parts are the same as those in the first embodiment, the same parts are denoted by the same reference numerals in the drawings, and description thereof is omitted.
(Function)
In the pneumatic run-flat tire 30, the side reinforcing layer 24 is constituted by three layers of reinforcing elements 24A, 24C, and 24D, the highest hardness of the reinforcing element 24D on the bead portion 12 side is the highest, and the reinforcing element on the tread portion 16 side. Since the hardness of 24A is the lowest, it is possible to reduce the gauge of the side reinforcing layer 24 while ensuring the run-flat performance, and to improve the riding comfort during normal use.

  Specifically, during run-flat running, the relatively hard reinforcing elements 24C and 24D (particularly the reinforcing element 24D) of the side reinforcing layer 24 are in a state of mainly supporting the vehicle weight, so that the longitudinal spring becomes large. . For this reason, the pneumatic run-flat tire 30 can withstand the load during run-flat travel, and large deformation of the tire is suppressed. Further, since the reinforcing elements 24A and 24B having a relatively low hardness and a large volume are arranged on the tread portion 16 side, the influence of the reinforcing elements 24C and 24D having a high hardness on the riding comfort during normal traveling can be reduced. The vertical spring becomes smaller and the ride comfort is improved. This effect is largely due to the reinforcement element 24A having a lower hardness and a larger volume among the reinforcement elements 24A and 24B.

  In addition, since the difference in hardness between the reinforcing elements can be further reduced as compared with the second embodiment, failure between the reinforcing elements is extremely unlikely to occur.

  In any of the above-described embodiments, the end portions on the tread portion 16 side of each reinforcing layer are terminated on the tire inner surface side. However, the present invention is not limited to this. For example, the carcass main body on the tire outer side You may make it each terminate on the part 18A side.

1 is a cross-sectional view of a pneumatic run flat tire according to a first embodiment. It is sectional drawing of the pneumatic run flat tire which concerns on 2nd Embodiment. It is sectional drawing of the pneumatic run-flat tire which concerns on 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic run-flat tire 12 Bead part 14 Side wall part 16 Tread part 18 Carcass 18A Carcass main-body part 18B Fold-up part 20 Pneumatic run-flat tire 22 Bead core 24 Side reinforcement layer 24A Reinforcement element 24B Reinforcement element 24C Reinforcement element 24D Reinforcement element 30 Pneumatic run flat tire

Claims (5)

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 disposed between the bead portions. A carcass having a carcass main body portion and a folded portion wound around a bead core of the bead portion from the inside to the outside, and the side wall portion of the side wall portion so that the thickness gradually decreases toward the bead portion and the tread portion. A pneumatic run flat tire provided with a side reinforcing layer disposed on the inner surface side,
The side reinforcing layer has a plurality of reinforcing elements having thicknesses that gradually decrease toward the bead part and the tread part, and having different JIS hardness,
The JIS hardness of each of the reinforcing elements decreases in order from the bead portion side to the tread portion side,
The volume of each said reinforcement element becomes large sequentially toward the said tread part side from the said bead part side, The pneumatic run-flat tire characterized by the above-mentioned.   The pneumatic run-flat tire according to claim 1, wherein the JIS hardness of the reinforcing element is 55 ° to 99 °, respectively. The side reinforcing layer is composed of two layers of the reinforcing elements, and the JIS hardness of each of the reinforcing elements is 55 ° to 85 ° on the tread portion side and 80 ° to 99 ° on the bead portion side,
2. The pneumatic run according to claim 1, wherein the proportion of each reinforcing element in the volume of the side reinforcing layer is 65 ± 10% on the tread portion side and 35 ± 5% on the bead portion side. Flat tire. The side reinforcing layer is composed of three layers of the reinforcing elements, and the JIS hardness of each of the reinforcing elements is 55 ° to 85 ° and 75 ° to 95 in order from the tread portion side to the bead portion side. °, 80 ° to 99 °,
The proportion of each reinforcing element in the volume of the side reinforcing layer is 35 ± 10%, 35 ± 10%, 30 ± 5% in order from the tread portion side to the bead portion side. The pneumatic run flat tire according to claim 1. The side reinforcing layer is composed of four layers of the reinforcing elements, and the JIS hardness of each of the reinforcing elements is 55 ° to 85 ° and 60 ° to 90 in order from the tread portion side to the bead portion side. °, 75 ° -95 °, 80 ° -99 °,
The ratio of each reinforcing element in the volume of the side reinforcing layer is 35 ± 10%, 25 ± 5%, 20 ± 10%, 20 ± 5% in order from the tread portion side to the bead portion side. The pneumatic run-flat tire according to claim 1, wherein the pneumatic run-flat tire is provided.

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