JP6537184B2 - Pneumatic tire - Google Patents

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 the circuit, it is effective to reduce the weight and increase the rigidity of the tire. In this regard, the present inventor considered omitting the inner liner that constitutes the inner surface of the tire in a normal tire structure, thereby achieving weight reduction. However, the omission of the inner liner needs to be improved since it causes deterioration of the air holding performance.

  Patent Document 1 describes a pneumatic tire which is not for competition but does not have an inner liner. In this tire, in order to secure the air holding performance, regarding the carcass ply constituting the inner surface of the tire, the topping rubber on the inner surface side is formed of rubber excellent in the air holding performance, and the topping rubber on the outer surface side is the inner surface side Is made of different rubber. In this technology, the carcass ply needs to have a special structure, which greatly limits the practical application range.

JP, 2006-159944, A

  The present invention has been made in view of the above situation, and an object thereof is to provide a pneumatic tire capable of achieving excellent exercise performance while securing air holding performance while realizing weight reduction by omitting an inner liner. It 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 a bead portion, a bead filler provided on the tire radial direction outer side of the bead core, and two carcass plies laminated to each other. A carcass layer, each of which is turned up through the bead core, and a belt layer provided on the radially outer side of the carcass layer, wherein the carcass layer constitutes a tire inner cavity surface, and at least The carcass ply has a super high turn-up end disposed on the inner side in the tire width direction with respect to the side end of the belt layer, and the reinforcing layer formed by rubber-coating a non-woven fabric of organic fibers is one carcass ply The upper end of the reinforcing layer is disposed inward in the tire width direction than the super 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 constitutes the tire inner cavity surface, and weight saving can be realized by omitting the inner liner. In addition, since the carcass layer has a super high turn-up structure, it contributes to high rigidity of the tire. According to the knowledge of the present inventor, in the tire having such an inner linerless structure, air is likely to permeate in the region extending from the side edge of the belt layer to the upper end of the bead filler, but the reinforcing layer is covered to cover the region. Since it is provided, air holding performance is secured. The reinforcing layer contributes to weight reduction of the tire because it is formed by rubber-coating a non-woven fabric of organic fibers.

  It is preferable that the reinforcing layer is provided on the inner surface of the carcass layer. According to this configuration, by providing the reinforcing layer on the inner surface of the carcass layer having relatively large bending deformation, it is possible to enhance rigidity and favorably improve exercise performance while securing air holding performance.

  The distance in the tire width direction between the super high turn-up end and the upper end of the reinforcing layer is equal to or larger than the distance in the tire width direction between the super high turn up end and the lateral end of the belt layer Is preferred. As a result, the upper end of the reinforcing layer is disposed at an appropriate distance from the ultra-high turn-up end, so that it is possible to prevent the deterioration of the durability due to the failure starting from the member end.

  It is preferable that the distance in the tire radial direction between the upper end of the bead filler and the lower end of the reinforcing layer is 20% or more of the height of the bead filler. Thereby, since the lower end of a reinforcement layer is arrange | positioned appropriately separated from the upper end of a bead filler, the deterioration of durability resulting from the failure which starts from the member end can be prevented.

  It is preferable that the rubber which covers the nonwoven fabric of the said reinforcement layer is butyl rubber, in order to ensure air holding performance favorably.

A tire meridian half sectional view showing an example of a pneumatic tire according to the present invention An enlarged view showing the main part of FIG. 1

  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 outward from the bead portions 1 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 on the outer side in the tire radial direction of the bead core 1a. The bead core 1a is formed by rubber-covering a convergent body such as a steel wire, and the bead filler 1b is formed of a rubber having a triangular cross-sectional shape which is tapered toward the outer side in the tire radial direction.

  The pneumatic tire T further includes a carcass layer 4 disposed between the pair of bead portions 1 to form a toroidal shape as a whole. The carcass layer 4 includes two carcass plies 41, 42 laminated to each other, each of which is turned up via the bead core 1a. The carcass plies 41 and 42 respectively extend from the tread portion 3 through the sidewall portion 2 to the bead portion 1 and are wound up from the inside in the tire width direction to the outside so as to sandwich the bead core 1a.

  The carcass plies 41 and 42 each have a cord extending obliquely with respect to the tire circumferential direction, and the carcass layer 4 has a bias structure stacked so that the cords are in the opposite direction to each other. The inclination angle of the cord with respect to the tire circumferential direction is set to, for example, 60 to 80 °. 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 on the radially outer side of the carcass layer 4. The belt layer 5 includes two belt plies 51 and 52 which have cords extending obliquely with respect to the circumferential direction of the tire and which are laminated such that the cords are opposite to each other. The inclination angle of the cord with respect to the tire circumferential direction is set to, for example, 20 to 30 °. The side end 5E points to the end of the widest belt ply (in the present embodiment, the belt ply 51) of the belt plies constituting the belt layer 5.

  A belt reinforcing layer 6 provided wider than the belt layer 5 is provided on the outer side in the tire radial direction of the belt layer 5. The belt reinforcing layer 6 is composed of 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 obtained by rubber-coating one or a plurality of cords.

  The tire T can ensure a ground contact area when a high driving force or lateral force is applied, in order to exhibit excellent exercise performance (mainly traction performance and cornering performance) as a pneumatic tire for competition. The belt is constructed as a semi-radial tire using a belt layer similar to the radial tire in combination with a bias structure.

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

  In the present embodiment, the carcass ply 41 has the super high turn-up end 41E disposed on the inner side in the tire width direction with respect to the side end 5E of the belt layer 5. Such an ultra-high turn-up structure in which the carcass ply 41 overlaps the belt layer 5 can achieve an increase in the rigidity of the tire, in particular, an effect of improving the longitudinal rigidity and the lateral rigidity. It may be at least one carcass ply having a super high turn-up end. Therefore, instead of or in addition to the carcass ply 41, the turn-up end (roll-up end) of the carcass ply 42 may be disposed on the inner side in the tire width direction than the side end 5E.

  Further, in the present embodiment, the reinforcing layer 7 (non-woven fabric reinforcing layer) formed by rubber-coating non-woven fabric of organic fibers is provided on the inner surface of the carcass ply 41. As the organic fibers, monofilament fibers such as polyester, rayon, nylon, aramid and the like can be used. Using a non-woven fabric of organic fibers 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 non-woven fabrics, but is preferably composed of one non-woven fabric from the viewpoint of weight reduction. The rubber covering the non-woven fabric is preferably rubber excellent in air retention performance, and specifically butyl rubber is preferable.

  In the present specification, the upper end of a member such as the bead filler 1b refers to the tire radial outer end of the member, and the lower end refers to the tire radial inner end 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. The lower end 7Ed of the reinforcing layer 7 is disposed on the inner side in the tire radial direction with respect to the upper end 1bE of the bead filler 1b. The reinforcing layer 7 extends continuously from the upper end 7Eu to the lower end 7Ed in the tire meridional section, and is provided annularly along the tire circumferential direction. The reinforcing layers 7 are preferably provided on both sides in the tire width direction.

  In the tire in which the inner liner is omitted, there is a concern that the air holding performance is lowered, and in particular, air tends to easily permeate in the 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 while the bead portion 1 is provided with the bead filler 1b and the tread portion 3 is provided with the belt layer 5 and the belt reinforcing layer 6, the number of members is small in the above-mentioned area between them and rubber It is considered that the thickness is relatively small. So, in this pneumatic tire T, the reinforcement layer 7 is provided so that the said area | region may be covered, and it is securing the air retention performance by it.

  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 laminated sheets, that is, the inner surface of the carcass layer 4, and the reinforcing layer 7 Is configured. According to this configuration, since the reinforcing layer 7 is provided on the inner surface of the carcass layer 4 having relatively large bending deformation, the rigidity can be enhanced and the exercise performance can be favorably improved while securing the air holding performance. The reinforcing layer 7 is provided on the inner surface or the outer surface of the carcass plies 41 and 42. Therefore, it is also possible to provide the reinforcing layer 7 on the outer surface of the carcass ply 41 (that is, the inner surface of the carcass ply 42) and the outer surface of the carcass ply 42.

  The distance D1 in the tire width direction between the super high turn-up end 41E and the upper end 7Eu of the reinforcing layer 7 is the same as the distance D2 in the tire width direction between the super high turn up end 41E and the lateral end 5E of the belt layer 5 Larger than is preferable. As a result, the upper end 7Eu is disposed so as to be appropriately separated from the super high turn-up end 41E, so that it is possible to prevent the deterioration of the durability due to the 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 larger than this, the reinforcing layer 7 becomes larger than necessary, and waste is caused in achieving weight reduction of the tire. The distance D2 is set to, for example, 10 to 20 mm.

  It is preferable that 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 be 20% or more of the height H1b of the bead filler 1b. As a result, the lower end 7Ed of the reinforcing layer 7 is disposed appropriately separated from the upper end 1bE of the bead filler 1b, so that it is possible to prevent the deterioration of the durability due to the failure starting from the member end. The distance D3 is preferably 80% or less of the height H1b. If the distance D3 is larger than the height H1b, the reinforcing layer 7 becomes larger than necessary, and waste is caused to reduce the weight of the tire. The height H1 b is set to, for example, 30 to 60% of the tire cross-sectional height TH.

  In the present embodiment, of the two carcass plies 41 and 42 laminated to each other, only one carcass ply 41 has a super high turn-up end, and the other carcass ply 42 is the tire width direction outer side of the bead filler 1 b. Have a turn up end 42E. 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 the turn-up portion (rolled up portion) of the carcass layer 4 and the bead filler 1 b in order to make the structure preferable as a racing pneumatic tire. The inclination angle of the steel cord with respect to the tire circumferential direction is set to, for example, 20 to 40 °. The lower end 7Ed of the reinforcing layer 7, the turnup end 42E of the carcass ply 42, and the upper end 1bE of the bead filler 1b are disposed at positions mutually separated in the tire radial direction.

  The upper end 8Eu of the steel side ply 8 is disposed radially outward of the upper end 1bE of the bead filler 1b, and is disposed, for example, in the range of 30 to 50% of the tire cross-sectional height TH from the bead baseline 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 outside the upper end of the bead core 1a in the tire radial direction and further inward than the lower end 7Ed of the reinforcing layer 7 in the tire radial direction.

  The JISA hardness (value measured at 25 ° C. according to JIS K6253 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 at least °°. As a result, the rigidity of the sidewall portion 2 can be enhanced, and a useful construction can be made as a racing pneumatic tire. In this tire T, a side-on-tread structure in which the end of the sidewall rubber 11 is placed on the end of the tread rubber 10 forming the outer surface of the tread portion 3 is adopted, but the present invention is not limited thereto.

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

  The pneumatic tire according to the present invention can ensure the air holding performance while realizing the weight reduction and can exhibit the excellent exercise performance while realizing the weight reduction by the action and effect as described above. It is useful as a pneumatic tire.

  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.

  Hereinafter, the example which shows concretely the composition and effect of the present invention is described. Each performance evaluation of the tire was performed as follows.

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

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

  The tires used for evaluation are dry road race tires of size 285 / 650R18, and except for the specifications shown in Table 1, the tire structure and rubber composition in each example are common. In "position of reinforcing layer" in Table 1, "inner surface" refers to a structure (see Figs. 1 and 2) in which a reinforcing layer is provided on the inner surface of the carcass layer, and "outer surface" is an 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 the weight reduction due to the omission of the inner liner. However, the air retention performance can be secured by providing the non-woven 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 6 of belt layer 6 belt reinforcement layer 7 reinforcement layer 7Ed reinforcement layer lower end 7Eu reinforcement layer top end 8 steel side ply 9 Lumen 11 sidewall rubber 41 carcass ply 41 E 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 tire radial direction outer side of the bead core;
A carcass layer comprising two carcass plies laminated to each other, each of which is turned up via said bead core,
A belt layer provided on the tire radial direction outer side of the carcass layer;
The carcass layer constitutes a tire bore surface,
At least one of the carcass plies has a super high turn-up end disposed inward in the tire width direction than a lateral end of the belt layer;
A reinforcing layer formed by rubber-coating a non-woven 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 inward in the tire width direction than the super high turn-up end. The pneumatic tire whose lower end of a layer is arranged inside the tire radial direction rather 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 super high turn-up end and the upper end of the reinforcing layer is equal to or larger than the distance in the tire width direction between the super high turn up end and the lateral end of the belt layer 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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