JP2013112131A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving cut resistance of a sidewall part.SOLUTION: This pneumatic tire 1 has a relationship of 1.20≤Go/Gi≤2.00 between a distance Go of an outside area and a distance Gi of an inside area, has a relationship of 1.05≤SWo/SWi≤1.20 between a distance SWo of the outside area and a distance SWi of the inside area, and has a relationship of 1.05≤Ri1/Ro1≤1.50 and 1.05≤Ri2/Ro2≤1.50 between curvature radii Ro1 and Ro2 of a profile line of the outside area and curvature radii Ri1 and Ri2 of the profile line of the inside area.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can improve cut resistance of a sidewall portion.

  In recent pneumatic tires, there is a demand to reduce cut damage of a sidewall portion located outside in the vehicle width direction when the vehicle is mounted. As a conventional pneumatic tire related to such a problem, a technique described in Patent Document 1 is known.

JP 2007-168543 A

  An object of the present invention is to provide a pneumatic tire capable of improving the cut resistance of the sidewall portion.

  In order to achieve the above object, a pneumatic tire according to the present invention is a pneumatic tire including a carcass layer and a sidewall rubber, and is one region having a tire equatorial plane as a boundary in a sectional view in the tire meridian direction. Is called the outer region and the other region is called the inner region, the distance Go from the tire maximum width position of the outer region to the carcass layer and the distance from the tire maximum width position of the inner region to the carcass layer Gi has a relationship of 1.20 ≦ Go / Gi ≦ 2.00, the distance SWo from the tire maximum width position in the outer region to the tire equator plane, and the tire equator from the tire maximum width position in the inner region The distance SWi to the surface has a relationship of 1.05 ≦ SPo / SWi ≦ 1.20, and the tire has a tire cross-sectional height outside in the tire radial direction from the maximum tire width position in the outer region. The curvature radius Ro1 of the profile line in the range up to 25% of SH and the curvature of the profile line in the range from the tire maximum width position in the inner region to the outer side in the tire radial direction and 25% of the tire cross-section height SH The radius Ri1 has a relationship of 1.05 ≦ Ri1 / Ro1 ≦ 1.50, and from the maximum tire width position of the outer region to the inner side in the tire radial direction and 25 [%] of the tire cross-section height SH. The curvature radius Ro2 of the profile line in the range and the curvature radius Ri2 of the profile line in the range from the tire maximum width position in the inner region to the inner side in the tire radial direction and 25 [%] of the tire cross-section height SH are 1.05. ≦ Ri2 / Ro2 ≦ 1.50.

  In the pneumatic tire according to the present invention, since the sidewall rubber in the outer region is thick (1.20 ≦ Go / Gi), the rigidity of the sidewall portion in the outer region is reinforced. Accordingly, there is an advantage that the cut resistance of the sidewall portion is improved when the pneumatic tire is mounted on the vehicle with the outer region positioned outside in the vehicle width direction.

FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is a table showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Pneumatic tire]
FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire 1 according to an embodiment of the present invention. The figure shows a radial tire for a passenger car as an example of the pneumatic tire 1. Reference sign CL is a tire equator plane.

  The pneumatic tire 1 includes a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, a tread rubber 15, a pair of sidewall rubbers 16, 16, and a pair. The bead rubbers 17 and 17 are provided.

  The pair of bead cores 11 and 11 has an annular structure and constitutes the core of the left and right bead portions. The pair of bead fillers 12 and 12 are disposed on the outer periphery in the tire radial direction of the pair of bead cores 11 and 11 to reinforce the bead portion.

  The carcass layer 13 has a single-layer structure and is bridged in a toroidal shape between the left and right bead cores 11 and 11 to constitute a tire skeleton. Further, both end portions of the carcass layer 13 are wound and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12. The carcass layer 13 is formed by coating a plurality of carcass cords made of steel or an organic fiber material (for example, nylon, polyester, rayon, etc.) with a coating rubber and rolling them, and has an absolute value of 85 [deg] or more and 95. [Deg] The following carcass angle (inclination angle in the fiber direction of the carcass cord with respect to the tire circumferential direction).

  The belt layer 14 is formed by laminating a pair of cross belts 141 and 142 and a belt cover 143, and is arranged around the outer periphery of the carcass layer 13. The pair of cross belts 141 and 142 is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and having a belt angle of 10 [deg] or more and 30 [deg] or less in absolute value. Have. Further, the pair of cross belts 141 and 142 have belt angles with different signs from each other (inclination angle of the fiber direction of the belt cord with respect to the tire circumferential direction), and are laminated so that the fiber directions of the belt cords cross each other. (Cross ply structure). The belt cover 143 is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coat rubber, and has a belt angle of 10 [deg] or more and 45 [deg] or less in absolute value. Further, the belt cover 143 is disposed so as to be laminated on the outer side in the tire radial direction of the cross belts 141 and 142.

  The tread rubber 15 is disposed on the outer circumference in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute a tread portion of the tire. The pair of side wall rubbers 16 and 16 are respectively arranged on the outer side in the tire width direction of the carcass layer 13 to constitute left and right side wall portions. The pair of bead rubbers 17, 17 are arranged on the outer sides in the tire width direction of the left and right bead cores 11, 11 and the bead fillers 12, 12 to constitute left and right bead portions.

[Sidewall]
Here, in recent pneumatic tires, there is a demand to reduce the cut damage of the sidewall portion located on the outer side in the vehicle width direction when the vehicle is mounted. Such cut damage occurs, for example, due to contact between the sidewall portion and the curbstone. As a configuration for suppressing such cut damage, there is a configuration in which the sidewall rubber on the outer side in the vehicle width direction is thick.

  However, if only the sidewall rubber on the outer side in the vehicle width direction is thick, the difference in rigidity between the left and right sidewall portions increases. Specifically, the rigidity of the sidewall portion on the outer side in the vehicle width direction increases, and it becomes difficult to deform. For this reason, the road surface followability of a tread part deteriorates, and there exists a subject that the steering stability performance of a tire falls.

  In view of this, the pneumatic tire 1 employs the following configuration in order to improve the anti-cut performance while securing the steering stability performance of the tire (see FIG. 1).

  First, in sectional view in the tire meridian direction, one region having the tire equatorial plane CL as a boundary is referred to as an outer region, and the other region is referred to as an inner region. In this embodiment, the pneumatic tire 1 is mounted on a vehicle with the outer region positioned outside in the vehicle width direction.

  At this time, the distance Go from the tire maximum width position Ao in the outer region to the carcass layer 13 and the distance Gi from the tire maximum width position Ai in the inner region to the carcass layer 13 are 1.20 ≦ Go / Gi ≦ 2. 00 relationship. These distances Go and Gi indicate gauges of the sidewall rubber 16 at the tire maximum width positions Ao and Ai. Further, since the sidewall rubber in the outer region is thick (1.20 ≦ Go / Gi), the rigidity of the sidewall portion in the outer region is reinforced. Further, in the configuration of FIG. 1, both end portions of the carcass layer 13 are rewound outward in the tire radial direction and are positioned on the outer side in the tire radial direction than the tire maximum width positions Ao and Ai. For this reason, the distances Go and Gi are the distances between the rewind end portion of the carcass layer 13 and the tire maximum width positions Ao and Ai.

  The tire maximum width positions Ao and Ai refer to the maximum width position of the tire cross-sectional width.

  The distance SWo from the tire maximum width position Ao in the outer region to the tire equatorial plane CL and the distance SWi from the tire maximum width position Ai in the inner region to the tire equatorial plane CL are 1.05 ≦ SPo / SWi ≦ 1. .20 relationship. In addition, the ratio SWo / SWi is preferably in the range of 1.10 ≦ SPo / SWi ≦ 1.15.

  Further, the curvature radius Ro1 of the profile line in the range from the tire maximum width position Ao in the outer region to the tire radial direction outer side and 25 [%] of the tire cross-section height SH, and the tire radial direction from the tire maximum width position Ai in the inner region The curvature radius Ri1 of the profile line in the range of up to 25% of the tire cross-section height SH has a relationship of 1.05 ≦ Ri1 / Ro1 ≦ 1.50. Further, the ratio Ri1 / Ro1 is preferably in the range of 1.20 ≦ Ri1 / Ro1 ≦ 1.30.

  Further, the curvature radius Ro2 of the profile line in the range from the tire maximum width position Ao in the outer region to the inner side in the tire radial direction and 25 [%] of the tire cross-section height SH, and the tire radial direction from the tire maximum width position Ai in the inner region. The curvature radius Ri2 of the profile line in the range up to 25% of the tire cross-section height SH has a relationship of 1.05 ≦ Ri2 / Ro2 ≦ 1.50. The ratio Ri2 / Ro2 is preferably in the range of 1.20 ≦ Ri2 / Ro2 ≦ 1.30.

  These curvature radii Ri1, Ro1, Ri2, and Ro2 define the outer shape of the sidewall portion. Further, by defining these curvature radii Ri1, Ro1, Ri2, and Ro2, profile lines in a range of ± 25 [%] of the tire cross-section height SH from the left and right tire maximum width positions Ao and Ai are optimized. The In addition, the left and right asymmetrical profile lines are formed by the difference between the left and right curvature radii. Further, since the curvature radii Ri1 and Ri2 of the inner region are large (1.05 ≦ Ri1 / Ro1 and 1.05 ≦ Ri2 / Ro2), the rigidity of the sidewall portion of the inner region is reinforced.

  Note that the tire cross-section height SH refers to ½ of the difference between the tire outer diameter and the rim diameter. The rim diameter is measured at the point of contact with the tire bead heel.

  The distances Go, Gi, SWo, SWi, the curvature radii Ri1, Ro1, Ri2, Ro2 and the tire cross-section height SH are applied to the rim specified by JATMA and applied with an internal pressure of 50 [kPa]. And measured as a no-load condition. Further, the numerical values of the distances Go, Gi, SWo, SWi and the radii of curvature Ri1, Ro1, Ri2, Ro2 can be appropriately set according to the tire size.

  Further, the rubber hardnesses Ho and Hi of the left and right sidewall rubbers 16 and 16 are in a range of 40 ≦ Ho ≦ 70 and 41 ≦ Hi ≦ 75. As a result, the rubber hardnesses Ho and Hi of the left and right sidewall rubbers 16 and 16 are optimized. Further, the rubber hardness Ho of the sidewall rubber 16 in the outer region and the rubber hardness Hi of the sidewall rubber 16 in the inner region have a relationship of 1 ≦ Hi−Ho ≦ 5. Thereby, the rigidity of the sidewall portion in the inner region is reinforced.

  In addition, rubber hardness means the JIS-A hardness based on JIS-K6263.

  Further, the loss tangents tanδ_o and tanδ_i of the left and right sidewall rubbers are in the range of 0.05 ≦ tanδ_o ≦ 0.20 and 0.06 ≦ tanδ_i ≦ 0.30. As a result, the loss tangents tanδ_o and tanδ_i of the left and right sidewall rubbers 16 and 16 are optimized. Further, the loss tangent tanδ_o of the sidewall rubber 16 in the outer region and the loss tangent tanδ_i of the sidewall rubber 16 in the inner region have a relationship of 0.01 ≦ tanδ_i−tanδ_o ≦ 0.10. The upper limit of the difference tanδ_i−tanδ_o is preferably tanδ_i−tanδ_o ≦ 0.15.

  The loss tangents tanδ_o and tanδ_i are measured using a viscoelastic spectrometer under the conditions of a temperature of 60 [° C.], a shear strain of 10 [%], and a frequency of 20 [Hz].

[effect]
As described above, the pneumatic tire 1 has the distance Go from the tire maximum width position Ao in the outer region to the carcass layer 13 and the distance Gi from the tire maximum width position Ai in the inner region to the carcass layer 13. 1.20 ≦ Go / Gi ≦ 2.00 (see FIG. 1). The distance SWo from the tire maximum width position Ao in the outer region to the tire equatorial plane CL and the distance SWi from the tire maximum width position Ai in the inner region to the tire equatorial plane CL are 1.05 ≦ SPo / SWi ≦ 1. .20 relationship. Further, the curvature radius Ro1 of the profile line in the range from the tire maximum width position Ao in the outer region to the tire radial direction outer side and 25 [%] of the tire cross-section height SH, and the tire radial direction from the tire maximum width position Ai in the inner region The curvature radius Ri1 of the profile line in the range of up to 25% of the tire cross-section height SH has a relationship of 1.05 ≦ Ri1 / Ro1 ≦ 1.50. Further, the curvature radius Ro2 of the profile line in the range from the tire maximum width position Ao in the outer region to the inner side in the tire radial direction and 25 [%] of the tire cross-section height SH, and the tire radial direction from the tire maximum width position in the inner region The curvature radius Ri2 of the profile line in the range up to 25% of the tire cross-section height SH has a relationship of 1.05 ≦ Ri2 / Ro2 ≦ 1.50.

  In such a configuration, (1) since the sidewall rubber 16 in the outer region is thick (1.20 ≦ Go / Gi), the rigidity of the sidewall portion in the outer region is reinforced. Accordingly, there is an advantage that the cut resistance of the sidewall portion is improved when the pneumatic tire 1 is mounted on the vehicle with the outer region positioned outside in the vehicle width direction. Further, (2) Since SPo> SWi, the curvature of the sidewall portion in the outer region is large, and an excessive increase in rigidity due to an increase in the side gauge is prevented. (3) Since the curvature radii Ri1 and Ri2 of the inner region are large (1.05 ≦ Ri1 / Ro1 and 1.05 ≦ Ri2 / Ro2), the rigidity of the sidewall portion of the inner region is reinforced. Thereby, there is an advantage that the rigidity difference between the outer region and the inner region is reduced, and the steering stability performance and durability performance of the tire are improved.

  In the pneumatic tire 1, the rubber hardness Ho of the sidewall rubber 16 in the outer region and the rubber hardness Hi of the sidewall rubber 16 in the inner region are within the range of 40 ≦ Ho ≦ 70 and 41 ≦ Hi ≦ 75. It is in. Thereby, the rubber hardness Ho and Hi of the sidewall rubbers 16 and 16 are optimized, and there is an advantage that the tire characteristics are appropriately secured.

  In the pneumatic tire 1, the rubber hardness Ho of the sidewall rubber 16 in the outer region and the rubber hardness Hi of the sidewall rubber 16 in the inner region have a relationship of 1 ≦ Hi−Ho ≦ 5. As a result, the rigidity of the sidewall portion in the inner region is reinforced, so that the rigidity between the outer region and the inner region due to the sidewall rubber 16 in the outer region being thick (1.20 ≦ Go / Gi). There is an advantage that the difference is eased. In particular, by adjusting both the above-described curvature radii Ri1, Ro1, Ri2, Ro2 and rubber hardness Ho, Hi, and reducing the rigidity difference between the outer region and the inner region, the left and right curvature radius ratio Ri1 / Ro1, The difference between Ri2 / Ro2 and the difference between the left and right rubber hardness Hi-Ho can be reduced, which is preferable.

  Further, in the pneumatic tire 1, the loss tangents tanδ_o and tanδ_i of the left and right sidewall rubbers are in the ranges of 0.05 ≦ tanδ_o ≦ 0.20 and 0.06 ≦ tanδ_i ≦ 0.30. As a result, the loss tangents tanδ_o and tanδ_i of the left and right sidewall rubbers 16 and 16 are optimized, and there is an advantage that the tire characteristics are appropriately ensured.

  In the pneumatic tire 1, the loss tangent tanδ_o of the sidewall rubber 16 in the outer region and the loss tangent tanδ_i of the sidewall rubber 16 in the inner region have a relationship of 0.01 ≦ tanδ_i−tanδ_o ≦ 0.10. Have. As described above, since the sidewall rubber 16 in the outer region is thick (1.20 ≦ Go / Gi), the amount of heat generated in the outer region increases, and the rolling resistance increases. Therefore, by setting the loss tangent tanδ_o of the sidewall rubber 16 in the outer region to be small, heat generation in the outer region is suppressed. Thereby, the rolling resistance on the left and right sides of the tire is made uniform, and there is an advantage that the high-speed durability performance of the tire is improved.

  In addition, the pneumatic tire 1 has a designation of the mounting direction to be mounted on the vehicle with the outer region being the outer side in the vehicle width direction (see FIG. 1). In such a configuration, the pneumatic tire 1 is attached to the vehicle with the outer region having the thick wall rubber (1.20 ≦ Go / Gi) 16 facing outward in the vehicle width direction. There is an advantage of improving the performance. In addition, designation | designated of a mounting direction can be displayed by the mark or unevenness | corrugation attached | subjected to the sidewall part of the tire, for example.

  FIG. 2 is a table showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  In this performance test, evaluations on (1) anti-cut performance, (2) steering stability performance, and (3) durability performance were performed on a plurality of different pneumatic tires (see FIG. 2). In this performance test, a pneumatic tire having a tire size of 195 / 65R15 91H is assembled to a rim having a rim size of 15 × 6J, and an air pressure of 210 [kPa] and a maximum load specified by JATMA are applied to the pneumatic tire. A 1800 [cc] class sedan is used as the test vehicle. In addition, the pneumatic tire 1 is mounted on the test vehicle with the outer region positioned outside in the vehicle width direction.

  (1) In the evaluation regarding the anti-cut performance, a test vehicle equipped with a pneumatic tire rides on a curb with a height of 110 [mm] at a traveling speed of 10 [km / h] and an approach angle of 30 [degrees]. Also, cracks (crack length and depth) generated in the sidewall portions are observed for the tire sample 100 [pieces]. Based on this observation result, index evaluation is performed with the conventional example as a reference (100). This evaluation is more preferable as the numerical value is larger, and if it is 105 or more, it is recognized that there is an advantage.

  (2) In the evaluation regarding the steering stability performance, a test vehicle equipped with a pneumatic tire travels on a test course having a flat circuit around 60 [km / h] to 100 [km / h]. Then, the test driver performs sensory evaluation on the steering performance at the time of race change and cornering and the stability at the time of straight traveling. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the better. Moreover, if evaluation is 100 or more, it can be said that performance is ensured appropriately.

  (3) The durability performance is evaluated by a low-pressure durability test using an indoor drum tester. Then, the number of cracks generated in the bead portion after traveling at a distance of 20000 [km] is measured, and based on the measurement result, index evaluation is performed using the conventional example as a reference (100). Moreover, if evaluation is 100 or more, it can be said that performance is ensured appropriately.

  The pneumatic tire 1 of Examples 1-11 has the structure described in FIG. In the first embodiment, Go = 4.8 [mm], Gi = 3.0 [mm], SWo = 113 [mm], SWi = 100 [mm], Ri1 = 62 [mm], Ro1 = 50 [ mm], Ri2 = 87 [mm], and Ro2 = 70 [mm].

  The conventional pneumatic tire has a symmetrical structure.

  As shown in the test results, it can be seen that the pneumatic tires 1 of Examples 1 to 11 can improve the cut resistance performance while maintaining the steering stability performance and the durability performance.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire, 11 Bead core, 12 Bead filler, 13 Carcass layer, 14 Belt layer, 141, 142 Cross belt, 143 Belt cover, 15 Tread rubber, 16 Side wall rubber, 17 Bead rubber

Claims (6)

A pneumatic tire comprising a carcass layer and sidewall rubber,
In the tire meridian cross-sectional view, when one region with the tire equator plane as a boundary is called an outer region and the other region is called an inner region,
The distance Go from the tire maximum width position in the outer region to the carcass layer and the distance Gi from the tire maximum width position in the inner region to the carcass layer satisfy the relationship of 1.20 ≦ Go / Gi ≦ 2.00. Have
A relationship SWo from the tire maximum width position of the outer region to the tire equator plane and a distance SWi from the tire maximum width position of the inner region to the tire equator plane is 1.05 ≦ SPo / SWi ≦ 1.20. Have
The curvature radius Ro1 of the profile line in the range from the tire maximum width position of the outer region to the tire radial direction outer side and 25 [%] of the tire cross-section height SH, and the tire radial width outer side from the tire maximum width position of the inner region and The curvature radius Ri1 of the profile line in the range up to 25% of the tire cross-section height SH has a relationship of 1.05 ≦ Ri1 / Ro1 ≦ 1.50, and
The curvature radius Ro2 of the profile line in the range from the tire maximum width position in the outer region to the tire radial inner side and 25 [%] of the tire cross-section height SH, and the tire radial inner side from the tire maximum width position in the inner region and A pneumatic tire characterized in that a curvature radius Ri2 of a profile line in a range up to 25 [%] of a tire cross-section height SH has a relationship of 1.05 ≦ Ri2 / Ro2 ≦ 1.50.   2. The rubber hardness Ho of the sidewall rubber in the outer region and the rubber hardness Hi of the sidewall rubber in the inner region are in a range of 40 ≦ Ho ≦ 70 and 41 ≦ Hi ≦ 75. Pneumatic tires.   The pneumatic tire according to claim 2, wherein a rubber hardness Ho of the sidewall rubber in the outer region and a rubber hardness Hi of the sidewall rubber in the inner region have a relationship of 1≤Hi-Ho≤5.   The loss tangent tanδ_o of the sidewall rubber in the outer region and the loss tangent tanδ_i of the sidewall rubber in the inner region are in a range of 0.05 ≦ tanδ_o ≦ 0.20 and 0.06 ≦ tanδ_i ≦ 0.30. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is inside.   The loss tangent tanδ_o of the sidewall rubber in the outer region and the loss tangent tanδ_i of the sidewall rubber in the inner region have a relationship of 0.01 ≦ tanδ_i−tanδ_o ≦ 0.10. Pneumatic tire.   The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire has a designation of a mounting direction to be mounted on the vehicle with the outer region being on the outer side in the vehicle width direction.

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