JP2017094776A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of securing an air holding performance and capable of exerting excellent maneuverability while achieving weight saving by abbreviation of an inner liner.SOLUTION: In a pneumatic tire, a carcass layer 4 includes two carcass plies 41, 42 laminated to each other, and each of the plies is turned up via a bead core 1a. The carcass layer 4 configures a tire inner cavity face, and the carcass ply 41 has a super-high turn-up end 41E disposed inside the lateral end 5E of a belt layer 5 in a tire width direction. Further, a reinforcing layer 7 comprising coating the non-woven cloth of an organic fiber with rubber is provided on the inner face of the carcass ply 41. Besides, the upper end 7Eu of the reinforcing layer 7 is disposed inside the super-high turn-up end 41E in the tire width direction, and the lower end 7Ed of the reinforcing layer 7 is disposed inside the upper end 1bE of a bead filler 1b in a tire radial direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire capable of achieving excellent exercise performance while securing air retention performance while realizing weight reduction by omitting an inner liner.

  In order to exhibit excellent athletic performance as a racing pneumatic tire (racing tire) used on a circuit, it is effective to reduce the weight and rigidity of the tire. With respect to this point, the inventor considered that the inner liner constituting the tire cavity surface in the normal tire structure is omitted, thereby reducing the weight. However, since the omission of the inner liner causes deterioration of the air retention performance, it is necessary to improve this.

  Patent Document 1 describes a pneumatic tire that is not for competition but omits an inner liner. In this tire, in order to ensure air retention performance, the topping rubber on the inner surface side of the carcass ply constituting the tire cavity surface is formed of rubber having excellent air retention performance, and the topping rubber on the outer surface side is formed on the inner surface side. It is made of different rubber. In this technique, since the carcass ply needs to have a special structure, the practical application range is greatly limited.

JP 2006-159944 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a pneumatic tire capable of achieving excellent exercise performance while ensuring air retention performance while realizing weight reduction by omitting an inner liner. There is to do.

  The above object can be achieved by the present invention as described below. That is, the pneumatic tire according to the present invention includes an annular bead core provided in the bead portion, a bead filler provided on the outer side in the tire radial direction of the bead core, and two carcass plies stacked on each other. Each comprising a carcass layer that is turned up via the bead core, and a belt layer provided on the outer side in the tire radial direction of the carcass layer, the carcass layer constituting a tire lumen surface, and at least One carcass ply has an ultra-high turn-up end disposed on the inner side in the tire width direction from the side end of the belt layer, and a reinforcing layer formed by rubber-covering an organic fiber non-woven fabric is the carcass ply. The upper end of the reinforcing layer is disposed on the inner side in the tire width direction than the ultra high turn-up end, and the lower end of the reinforcing layer is In which is disposed on the inner side in the tire radial direction than the upper end of the serial bead filler.

  In this pneumatic tire, the carcass layer forms the tire cavity surface, and weight reduction can be realized by omitting the inner liner. Moreover, since the carcass layer has an ultra-high turn-up structure, it contributes to high rigidity of the tire. According to the inventor's knowledge, in such a tire having an inner linerless structure, air easily passes through a region extending from the side edge of the belt layer to the upper end of the bead filler, but a reinforcing layer is provided so as to cover the region. Since it is provided, air retention performance is ensured. Since the reinforcing layer is formed by covering an organic fiber non-woven fabric with rubber, it contributes to weight reduction of the tire.

  It is preferable that the reinforcing layer is provided on the inner surface of the carcass layer. According to such a configuration, the reinforcing layer is provided on the inner surface of the carcass layer that is relatively large in deformation, so that the rigidity can be improved and the exercise performance can be improved satisfactorily while ensuring the air retention performance.

  The distance in the tire width direction between the ultra-high turn-up end and the upper end of the reinforcing layer is equal to or greater than the distance in the tire width direction between the ultra-high turn-up end and the side edge of the belt layer. Is preferred. Thereby, since the upper end of the reinforcing layer is disposed at a suitable distance from the ultra high turn-up end, it is possible to prevent deterioration in durability due to a failure starting from the member end.

  The distance between the upper end of the bead filler and the lower end of the reinforcing layer in the tire radial direction is preferably 20% or more of the height of the bead filler. Thereby, since the lower end of a reinforcement layer is arrange | positioned moderately away from the upper end of a bead filler, the deterioration of durability resulting from the failure starting from a member end can be prevented.

  In order to ensure good air retention performance, it is preferable that the rubber covering the nonwoven fabric of the reinforcing layer is butyl rubber.

The tire meridian half sectional view showing an example of a pneumatic tire according to the present invention Enlarged view showing the main part of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The pneumatic tire T shown in FIGS. 1 and 2 includes a pair of bead portions 1, sidewall portions 2 extending from the bead portions 1 outward in the tire radial direction, and tire radial directions of the sidewall portions 2. A tread portion 3 connected to the outer end, an annular bead core 1a provided in the bead portion 1, and a bead filler 1b provided outside the bead core 1a in the tire radial direction are provided. The bead core 1a is formed by covering a converging body such as a steel wire with rubber, and the bead filler 1b is formed of rubber having a triangular cross section that tapers outward in the tire radial direction.

  The pneumatic tire T further includes a carcass layer 4 that is disposed between the pair of bead portions 1 and has a toroidal shape as a whole. The carcass layer 4 includes two carcass plies 41 and 42 stacked on each other, each of which is turned up via a bead core 1a. Each of the carcass plies 41 and 42 extends from the tread portion 3 through the sidewall portion 2 to the bead portion 1 and is wound up from the inner side in the tire width direction to the outer side so as to sandwich the bead core 1a.

  Each of the carcass plies 41 and 42 has a cord that extends while inclining with respect to the tire circumferential direction, and the carcass layer 4 has a bias structure that is laminated so that the cords are opposite to each other. The inclination angle of the cord with respect to the tire circumferential direction is set to 60 to 80 °, for example. For the cords of the carcass plies 41 and 42, for example, steel cords or organic fiber cords such as polyester, rayon, nylon, and aramid are used.

  The pneumatic tire T further includes a belt layer 5 provided outside the carcass layer 4 in the tire radial direction. The belt layer 5 includes two belt plies 51 and 52 each having a cord extending inclined with respect to the tire circumferential direction and laminated so that the cords are opposite to each other. The inclination angle of the cord with respect to the tire circumferential direction is set to 20 to 30 °, for example. The side end 5E indicates the end of the widest belt ply (belt ply 51 in the present embodiment) of the belt plies constituting the belt layer 5.

  A belt reinforcing layer 6 that is wider than the belt layer 5 is provided on the outer side of the belt layer 5 in the tire radial direction. The belt reinforcing layer 6 is constituted by a cap ply having a cord extending substantially parallel to the tire circumferential direction. The inclination angle of the cord with respect to the tire circumferential direction is preferably set to 10 ° or less, more preferably 3 ° or less. The belt reinforcing layer 6 is formed, for example, by spirally winding a long rubber member formed by rubber-coating one or a plurality of cords.

  This tire T is able to secure a ground contact area especially when high driving force or lateral force is applied so that it can exhibit excellent movement performance (mainly traction performance and cornering performance) as a pneumatic tire for competition. This is configured as a semi-radial tire in which a belt layer similar to that of a radial tire is used in combination with a bias structure.

  This pneumatic tire T has an inner liner-less structure in which an inner liner constituting the tire lumen surface is omitted in a normal tire structure. Since the inner liner is not provided, the carcass layer 4 faces the inner cavity 9 of the tire, and the carcass layer 4 constitutes the tire inner cavity surface. By omitting the inner liner, the weight of the tire can be reduced.

  In the present embodiment, the carcass ply 41 has an ultra-high turn-up end 41E disposed on the inner side in the tire width direction from the side end 5E of the belt layer 5. With such an ultra-high turn-up structure in which the carcass ply 41 overlaps the belt layer 5, it is possible to increase the rigidity of the tire, in particular, to improve the longitudinal rigidity and lateral rigidity. It may be at least one carcass ply having an ultra high turn-up end. Therefore, instead of or in addition to the carcass ply 41, the turn-up end (winding end) of the carcass ply 42 may be disposed on the inner side in the tire width direction from the side end 5E.

  In the present embodiment, a reinforcing layer 7 (nonwoven fabric reinforcing layer) formed by rubber-coating a nonwoven fabric of organic fibers is provided on the inner surface of the carcass ply 41. Monofilament fibers such as polyester, rayon, nylon, and aramid can be used as the organic fibers. Use of an organic fiber non-woven fabric as the reinforcing layer 7 is advantageous in reducing the weight of the tire T. The reinforcing layer 7 may be composed of a plurality of layers of nonwoven fabric, but is preferably composed of a single layer of nonwoven fabric from the viewpoint of weight reduction. The rubber covering the nonwoven fabric is preferably rubber excellent in air retention performance, and specifically butyl rubber.

  In the present specification, the upper end of a member such as the bead filler 1b indicates an end on the outer side in the tire radial direction of the member, and the lower end indicates an end on the inner side in the tire radial direction of the member. The upper end 7Eu of the reinforcing layer 7 is disposed on the inner side in the tire width direction than the super high turn-up end 41E. Further, the lower end 7Ed of the reinforcing layer 7 is disposed on the inner side in the tire radial direction from the upper end 1bE of the bead filler 1b. The reinforcing layer 7 continuously extends from the upper end 7Eu to the lower end 7Ed in the tire meridian cross section, and is provided in an annular shape along the tire circumferential direction. The reinforcing layer 7 is preferably provided on both sides in the tire width direction.

  In a tire in which the inner liner is omitted, there is a concern about a decrease in air retention performance, and air tends to easily permeate in a region extending from the side end 5E of the belt layer 5 to the upper end 1bE of the bead filler 1b. The reason is that the bead portion 1 is provided with a bead filler 1b, and the tread portion 3 is provided with a belt layer 5 and a belt reinforcing layer 6, whereas in the region between them, the number of members is small and rubber is provided. This is probably because the thickness is relatively small. Therefore, in the pneumatic tire T, the reinforcing layer 7 is provided so as to cover the region, thereby ensuring air retention performance.

  The reinforcing layer 7 of the present embodiment is provided on the inner surface of the carcass ply 41 disposed on the inner surface side of the two stacked layers, that is, on the inner surface of the carcass layer 4, and the reinforcing layer 7 provides a part of the tire lumen surface. Is configured. According to such a configuration, since the reinforcing layer 7 is provided on the inner surface of the carcass layer 4 that is relatively large in deformation, the rigidity can be increased and the exercise performance can be improved satisfactorily while ensuring the air retention performance. The reinforcing layer 7 is provided on the inner surface or the outer surface of the carcass plies 41, 42. Accordingly, the reinforcing layer 7 can be provided on the outer surface of the carcass ply 41 (that is, the inner surface of the carcass ply 42) or on the outer surface of the carcass ply 42.

  The distance D1 in the tire width direction between the ultra-high turn-up end 41E and the upper end 7Eu of the reinforcing layer 7 is the same as or equal to the distance D2 in the tire width direction between the ultra-high turn-up end 41E and the lateral end 5E of the belt layer 5 Is preferably larger. As a result, the upper end 7Eu is disposed at an appropriate distance from the ultra high turn-up end 41E, so that it is possible to prevent deterioration in durability due to a failure starting from the member end. The distance D1 is preferably equal to or less than twice the distance D2. If the distance D1 is exceeded, the reinforcing layer 7 becomes unnecessarily large, and waste is generated in reducing the weight of the tire. The distance D2 is set to 10 to 20 mm, for example.

  The distance D3 in the tire radial direction between the upper end 1bE of the bead filler 1b and the lower end 7Ed of the reinforcing layer 7 is preferably 20% or more of the height H1b of the bead filler 1b. Thereby, since the lower end 7Ed of the reinforcement layer 7 is arrange | positioned moderately away from the upper end 1bE of the bead filler 1b, the deterioration of durability resulting from the failure which makes a member end the starting point can be prevented. The distance D3 is preferably 80% or less of the height H1b. If the distance D3 is exceeded, the reinforcing layer 7 becomes unnecessarily large, and waste is generated in reducing the weight of the tire. The height H1b is set to 30 to 60% of the tire cross-section height TH, for example.

  In the present embodiment, only one of the two carcass plies 41 and 42 stacked on each other has an ultra-high turn-up end, and the other carcass ply 42 is outside the bead filler 1b in the tire width direction. Has a turn-up end 42E disposed on the surface. The distance L4 in the tire radial direction between the upper end 1bE of the bead filler 1b and the turn-up end 42E is, for example, 30 to 70% of the height H1b of the bead filler 1b.

  A steel side ply 8 having a steel cord is provided between a turn-up portion (rolled portion) of the carcass layer 4 and the bead filler 1b in order to obtain a structure preferable as a pneumatic tire for competition. The inclination angle of the steel cord with respect to the tire circumferential direction is set to 20 to 40 °, for example. The lower end 7Ed of the reinforcing layer 7, the turn-up end 42E of the carcass ply 42, and the upper end 1bE of the bead filler 1b are arranged at positions separated from each other in the tire radial direction.

  The upper end 8Eu of the steel side ply 8 is disposed on the outer side in the tire radial direction from the upper end 1bE of the bead filler 1b. For example, the upper end 8Eu is disposed in a range of 30 to 50% of the tire cross-section height TH from the bead base line BL. The lower end 8Ed of the steel side ply 8 is disposed between the bead core 1a and the lower end 7Ed of the reinforcing layer 7. Specifically, the lower end 8Ed is disposed on the outer side in the tire radial direction from the upper end of the bead core 1a and on the inner side in the tire radial direction from the lower end 7Ed of the reinforcing layer 7.

  The JISA hardness (value measured at 25 ° C. according to JISK6253 durometer hardness test (type A)) of the sidewall rubber 11 constituting the outer surface of the sidewall portion 2 is preferably 60 ° or more, 70 More preferably, it is not less than °. Thereby, the rigidity of the side wall part 2 can be improved and it can be set as a useful structure as a pneumatic tire for competitions. The tire T employs a side-on-tread structure in which the end portion of the sidewall rubber 11 is placed on the end portion of the tread rubber 10 constituting the outer surface of the tread portion 3, but is not limited thereto.

  The above-described positional relationship between the member ends, the tire cross-section height TH, and the like are determined in a no-load state in which a tire is mounted on an application rim and a predetermined internal pressure is applied. Applicable rims are industrial standards effective in the region where tires are produced and used, and are rims specified in JATMAYEAR BOOK in Japan, ETRTOSTANDARD MANUAL in Europe, and TRAYEAR BOOK in the United States. The predetermined internal pressure refers to an air pressure (maximum air pressure) corresponding to a tire maximum load capacity of a standard such as JATMA in a tire of an applicable size.

  The pneumatic tire according to the present invention has the above-mentioned effects and can achieve weight retention while ensuring air retention performance and exhibit excellent exercise performance. It is useful as a pneumatic tire for automobiles.

  The present invention is not limited to the embodiment described above, and various improvements and modifications can be made without departing from the spirit of the present invention.

  Examples that specifically show the structure and effects of the present invention will be described below. Each performance evaluation of the tire was performed as follows.

Lap time (exercise performance)
Tires were mounted on a real vehicle (race vehicle) and the lap time of the closed circuit measured by a professional driver was measured. The result of Comparative Example 1 is evaluated as an index with the value of 100, and the larger the value, the faster the lap time and the better the exercise performance.

Air retention performance A tire subjected to standard internal pressure was left in a temperature-controlled room for 3 months, and the internal pressure thereafter was measured to obtain a ratio (air retention ratio) to the initial internal pressure. The result of Comparative Example 1 is evaluated as an index with the value of 100, and the larger the numerical value, the higher the air retention rate and the better the air retention performance.

  The tire used for the evaluation is a race tire for dry road surface of size 285 / 650R18, and the tire structure and rubber composition in each example are common except for the specifications shown in Table 1. In “Position of reinforcing layer” in Table 1, “inner surface” refers to a structure (see FIGS. 1 and 2) in which the reinforcing layer is provided on the inner surface of the carcass layer, and “outer surface” refers to the outer surface of the carcass layer. Refers to the structure provided in The evaluation results are shown in Table 1.

  As shown in Table 1, in each of Examples 1 to 6, the lap time is better than that of Comparative Example 1, and excellent exercise performance can be exhibited based on weight reduction by omitting the inner liner. Nevertheless, air retention performance can be secured by providing the nonwoven fabric reinforcing layer as described above.

DESCRIPTION OF SYMBOLS 1 Bead part 1a Bead core 1b Bead filler 2 Side wall part 3 Tread part 4 Carcass layer 5 Belt layer 5E Side edge of belt layer 6 Belt reinforcement layer 7 Reinforcement layer 7Ed Lower end of reinforcement layer 7Eu Upper end of reinforcement layer 8 Steel side ply 9 Lumen 11 Side wall rubber 41 Carcass ply 41E Super high turn-up end 42 Carcass ply

Claims (5)

An annular bead core provided in the bead portion;
A bead filler provided on the outer side in the tire radial direction of the bead core;
A carcass layer including two carcass plies laminated together, each of which is turned up via the bead core;
A belt layer provided on the outer side in the tire radial direction of the carcass layer,
The carcass layer constitutes a tire cavity surface;
At least one of the carcass plies has a super high turn-up end disposed on the inner side in the tire width direction from the side end of the belt layer,
A reinforcing layer formed by rubber-coating a nonwoven fabric of organic fibers is provided on the inner surface or the outer surface of the carcass ply, and the upper end of the reinforcing layer is disposed on the inner side in the tire width direction than the ultra high turn-up end, and the reinforcing A pneumatic tire in which the lower end of the layer is disposed on the inner side in the tire radial direction than the upper end of the bead filler.   The pneumatic tire according to claim 1, wherein the reinforcing layer is provided on an inner surface of the carcass layer.   The distance in the tire width direction between the ultra-high turn-up end and the upper end of the reinforcing layer is equal to or greater than the distance in the tire width direction between the ultra-high turn-up end and the lateral end of the belt layer. Item 3. The pneumatic tire according to Item 1 or 2.   The pneumatic tire according to any one of claims 1 to 3, wherein a distance in a tire radial direction between an upper end of the bead filler and a lower end of the reinforcing layer is 20% or more of a height of the bead filler. The pneumatic tire according to any one of claims 1 to 4, wherein the rubber covering the nonwoven fabric of the reinforcing layer is butyl rubber.

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