JP2018108749A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of exhibiting excellent steering stability performance and riding comfort performance. An upper end 6E of a side reinforcing layer 6 extending in the tire radial direction from a bead portion 1 to a sidewall portion 2 is arranged outside the upper end 1bE of a bead filler 1b in the tire radial direction. The rim strip rubber 8 extends in the tire radial direction between the carcass layer 4 and the sidewall rubber 7, and the upper end 8E of the rim strip rubber 8 is arranged outside the upper end 6E of the side reinforcing layer 6 in the tire radial direction. Has been done. The winding end 4E of the carcass layer 4 is arranged outside the upper end 6E of the side reinforcing layer 6 in the tire radial direction, and is close to the upper end 8E of the rim strip rubber 8 via a distance of 5 mm or less in the tire radial direction. There is. [Selection diagram] Fig. 1

Description

  The present invention relates to a pneumatic tire capable of exhibiting excellent steering stability performance and riding comfort performance.

  Conventionally, a pneumatic tire provided with a side reinforcing layer extending in a tire radial direction from a bead portion to a sidewall portion in order to improve steering stability performance is known. The side reinforcing layer is generally formed by a ply (side ply) in which a plurality of steel cords arranged in parallel with each other are covered with rubber. For this reason, there is a large rigidity step at the upper end of the side reinforcing layer, and the ride comfort performance tends to deteriorate due to the accompanying increase in bottom sensation (shock feeling).

  Patent Documents 1 to 3 each describe a tire structure in which the upper end of the rim strip rubber is arranged on the outer side in the tire radial direction than usual. According to the knowledge of the present inventor, by arranging the upper end of the rim strip rubber on the outer side in the tire radial direction as described above, although the effect of absorbing the bottom butt feeling during running is somewhat exhibited, the side reinforcing layer Since the load acting on the upper end of the vehicle is still large, the effect of improving the riding comfort performance cannot be said to be sufficient, and there is room for further improvement.

JP 2014-54925 A JP 2013-241043 A JP 2003-31213 A

  This invention is made | formed in view of the said situation, The objective is to provide the pneumatic tire which can exhibit the outstanding steering stability performance and riding comfort performance.

  A pneumatic tire according to the present invention includes a carcass layer extending from a tread portion through a sidewall portion to a bead portion, a side reinforcing layer extending in a tire radial direction from the bead portion to the sidewall portion, and the side A sidewall rubber that forms the outer surface of the wall portion, and a rim strip rubber that forms the outer surface of the bead portion, and the bead portion is provided with an annular bead core and on the outer side in the tire radial direction of the bead core. The carcass layer is wound up so as to sandwich the bead filler, and the upper end of the side reinforcing layer is disposed on the outer side in the tire radial direction from the upper end of the bead filler. The rim strip rubber extends in the tire radial direction between the layer and the sidewall rubber, and the rim strip rubber The upper end of the rubber band is disposed on the outer side in the tire radial direction from the upper end of the side reinforcing layer, the winding end of the carcass layer is disposed on the outer side in the tire radial direction from the upper end of the side reinforcing layer, and the tire It is close to the upper end of the rim strip rubber through a distance of 5 mm or less in the radial direction.

  In this tire, the upper end of the side reinforcing layer is arranged outside the upper end of the bead filler in the tire radial direction, and the upper end of the rim strip rubber is arranged outside the upper end of the side reinforcing layer in the tire radial direction. The winding end of the carcass layer is disposed in the vicinity of the upper end of the carcass layer. For this reason, a rigid level | step difference becomes large also at the upper end of rim strip rubber similarly to the upper end of a side reinforcement layer and the upper end of a bead filler. As a result, three parts with large rigidity steps are provided away from each other in the tire radial direction, and the load is distributed among these three parts to reduce the feeling of bottoming during running, and excellent steering stability and ride comfort Performance can be demonstrated.

  From the viewpoint of further increasing the rigidity step at the upper end of the rim strip rubber so as to approach the rigidity step at the upper end of the side reinforcing layer, the winding end of the carcass layer is connected to the rim strip rubber through a distance of 3 mm or less in the tire radial direction. It is preferable to be close to the upper end, and it is more preferable that the rolled-up end of the carcass layer is coincident with the upper end of the rim strip rubber.

  It is preferable that the upper end of the rim strip rubber is disposed 20 mm or more away from the upper end of the side reinforcing layer outward in the tire radial direction. In this way, by properly separating the upper end of the rim strip rubber from the upper end of the side reinforcing layer, it is possible to satisfactorily ensure the bottom-up absorption effect.

  From the viewpoint of preventing the rigidity step from becoming too large at the upper end of the side reinforcing layer, it is preferable that the upper end of the side reinforcing layer is disposed 5 mm or more away from the upper end of the bead filler outward in the tire radial direction.

  The height of the rim strip rubber based on the outer diameter position of the bead core is preferably 70% or more of the height of the tire outer diameter position. By increasing the height of the rim strip rubber in this way, the rigidity of the buttress area can be increased and the steering stability performance can be effectively improved, and the rim strip rubber can also enhance the bottom impact feeling and improve the riding comfort performance. It can be improved effectively.

  From the viewpoint of suppressing deterioration in riding comfort performance due to the arrangement of the side reinforcing layer, it is preferable that the upper end of the side reinforcing layer is arranged on the inner side in the tire radial direction from the tire maximum width position.

Tire meridian partial sectional view showing an example of a pneumatic tire according to the present invention

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

  A pneumatic tire T shown in FIG. 1 includes a pair of bead portions 1, sidewall portions 2 that extend outward in the tire radial direction from each of the bead portions 1, and tire radial direction outer ends of the sidewall portions 2. A tread portion 3 is provided. In the bead portion 1, an annular bead core 1a and a bead filler 1b provided on the outer side in the tire radial direction of the bead core 1a are embedded. The bead core 1a is formed by covering a converging body such as a steel wire with rubber. The bead filler 1b is formed of a hard rubber having a triangular cross section extending outward in the tire radial direction. The buttress region 2B is a region on the outer side in the tire radial direction of the sidewall portion 2, and is a region that does not come into contact with the ground during normal traveling on a flat paved road.

  The pneumatic tire T further includes a carcass layer 4 that extends from the tread portion 3 through the sidewall portion 2 to the bead portion 1, a tread rubber 5 that forms an outer surface of the tread portion 3, and a sidewall portion from the bead portion 1. 2, a side reinforcing layer 6 extending in the tire radial direction, a sidewall rubber 7 that forms the outer surface of the sidewall portion 2, and a rim strip rubber 8 that forms the outer surface of the bead portion 1. Inside the carcass layer 4 is provided an inner liner rubber 9 for maintaining air pressure. A belt layer 10 laminated on the carcass layer 4 and a belt reinforcing layer 11 laminated on the belt layer 10 are provided inside the tread rubber 5 in the tire radial direction.

  The carcass layer 4 is formed of a carcass ply in which a plurality of cords arranged in a direction substantially orthogonal to the tire circumferential direction are covered with rubber. As the material of the cord, organic fibers such as polyester, rayon, nylon, and aramid are preferably used. The carcass layer 4 is composed of one carcass ply, but a plurality of stacked carcass plies may be used instead.

  The carcass layer 4 is wound up (turned up) in the bead portion 1 so as to sandwich the bead core 1a and the bead filler 1b. In other words, the carcass layer 4 is a series of winding plies arranged on the outer side in the tire width direction of the bead core 1a and the bead filler 1b on the main body ply from the tread portion 3 through the sidewall portion 2 to the bead portion 1. It is provided. The winding end 4E is an end portion of the wound carcass layer 4 (winding ply).

  The belt layer 10 is formed of a belt ply in which a plurality of cords arranged in a direction inclined with respect to the tire circumferential direction are covered with rubber. The belt layer 10 is composed of a plurality of (two in this embodiment) belt plies, and the cords are laminated so that the cords cross in opposite directions between the plies. Steel is preferably used as the material of the cord. The belt reinforcing layer 11 is formed of a reinforcing ply in which a cord that extends substantially in the tire circumferential direction is covered with rubber. As the cord material, the organic fiber as described above is preferably used. By covering the end portion of the belt layer 10 with the belt reinforcing layer 11, the high-speed durability can be improved by suppressing the lifting of the belt ply during high-speed running.

  The side reinforcing layer 6 is formed of a side ply in which a plurality of steel cords arranged in parallel with each other are covered with rubber. In the present embodiment, steel cords are arranged in a direction inclined with respect to the tire circumferential direction. The lower end (inner end in the tire radial direction) of the side reinforcing layer 6 is disposed on the side of the bead core 1a. The side reinforcing layer 6 is provided so as to be interposed between the bead filler 1b and the winding ply of the carcass layer 4, but may be provided so as to be bonded to the outer side in the tire width direction of the carcass layer 4. .

  The bead portion 1 of the tire T of the present embodiment is formed with a rim protector 12 whose outer surface is raised outward in the tire width direction. The rim protector 12 has a function of preventing deformation and damage of the rim flange caused by contact with a curb on the road shoulder. A rim strip rubber 8 is connected to the inner side in the tire radial direction of the sidewall rubber 7, and an exposed position of the interface is set to the rim protector 12. In addition, the pneumatic tire of this invention is not restricted to the thing in which such a rim protector was formed.

  The tire maximum width position 14 is a position where the profile line of the outer surface of the tire T in the sidewall portion 2 is farthest from the tire equator in the tire width direction. This profile line is an outline of the outer surface of the sidewall main body excluding protrusions such as the rim protector 12, and usually has a tire meridian cross-sectional shape defined by smoothly connecting a plurality of arcs.

  The rim strip rubber 8 is provided at a portion that contacts a rim (not shown) on which the tire T is mounted. The rim strip rubber 8 is formed of rubber having excellent wear resistance, and the modulus of the rim strip rubber 8 is higher than that of the sidewall rubber 7. However, since the rim strip rubber 8 of the present embodiment extends in the tire radial direction and is disposed on the sidewall portion 2, the modulus of the rim strip rubber 8 is a bead filler from the viewpoint of not excessively increasing the longitudinal rigidity of the tire T. Preferably it is lower than the modulus of 1b. The modulus refers to a 100% elongation modulus (M100) measured according to JISK6251.

  In this pneumatic tire T, the upper end 6E of the side reinforcing layer 6 is disposed on the outer side in the tire radial direction than the upper end 1bE of the bead filler 1b. Further, the rim strip rubber 8 extends in the tire radial direction between the carcass layer 4 and the sidewall rubber 7, and the upper end 8E of the rim strip rubber 8 is outside of the upper end 6E of the side reinforcing layer 6 in the tire radial direction. Is arranged. Further, the rolled-up end 4E of the carcass layer 4 is disposed on the outer side in the tire radial direction with respect to the upper end 6E of the side reinforcing layer 6 and close to the upper end 8E of the rim strip rubber 8 via a distance of 5 mm or less in the tire radial direction. doing. The upper end indicates the outer end of the member in the tire radial direction.

  The rigidity step is large at the upper end 6E of the side reinforcing layer 6 including the steel cord, and the rigidity step is also large at the upper end 1bE of the bead filler 1b formed of hard rubber. The upper end 8E of the rim strip rubber 8 and the winding end 4E of the carcass layer 4 have a smaller rigidity step than the upper end 6E and the upper end 1bE. However, in this tire T, the winding end 4E is close to the upper end 8E. As with the upper end 1bE, the rigidity step is also increased at the upper end 8E of the rim strip rubber 8. As a result, three parts with large rigidity steps are provided away from each other in the tire radial direction, and the load is distributed among these three parts to reduce the feeling of bottoming during running, and excellent steering stability and ride comfort Performance can be demonstrated.

  From the viewpoint of further increasing the rigidity step at the upper end 8E of the rim strip rubber 8 and approaching the rigidity step at the upper end 6E of the side reinforcing layer 6, the winding end 4E of the carcass layer 4 passes through a distance of 3 mm or less in the tire radial direction. The upper end 8E of the rim strip rubber 8 is preferably close to the upper end 8E, and the winding end 4E of the carcass layer 4 is more preferably aligned with the upper end 8E of the rim strip rubber 8. In this embodiment, the winding-up end 4E is made to coincide with the upper end 8E. In such a case, it is effective to taper the upper end 8E in order to prevent air entry during tire molding.

  The upper end 8E of the rim strip rubber 8 is preferably disposed 20 mm or more away from the upper end 6E of the side reinforcing layer 6 outward in the tire radial direction. In this way, by properly separating the upper end 8E of the rim strip rubber 8 from the upper end 6E of the side reinforcing layer 6, it is possible to satisfactorily secure the absorption effect of the bottom butt feeling by the rim strip rubber 8.

  The height Hr of the rim strip rubber 8 based on the outer diameter position of the bead core 1a is preferably 70% or more of the height Ht of the tire outer diameter position. By increasing the height of the rim strip rubber 8, the rigidity of the buttress area 2 </ b> B can be increased to improve the steering stability performance, and the rim strip rubber 8 can effectively improve the riding comfort performance by enhancing the bottom-up feeling absorption effect. It can be improved. The reference line SL is an imaginary straight line that extends in the tire width direction through the outer diameter position of the bead core 1a. The distance in the tire radial direction from the reference line SL to the upper end 8E of the rim strip rubber 8 is the height Hr, and the distance in the tire radial direction to the tire outer diameter position is also the height Ht.

  From the viewpoint of increasing the rigidity of the buttress region 2B, the height Hr ′ of the rim strip rubber 8 based on the bead base line BL is preferably 75% or more of the tire cross-sectional height Ht ′. In the present embodiment, the upper end 8E of the rim strip rubber 8 does not reach the tread rubber 5, but is not limited thereto. The height of the rim strip rubber 8 is substantially constant along the tire circumferential direction.

  In the present embodiment, the thickness of the rim strip rubber 8 gradually decreases from the exposed position of the interface between the sidewall rubber 7 and the rim strip rubber 8 toward the outer side in the tire radial direction. Therefore, the change in rigidity due to the rim strip rubber 8 becomes gradual, which is convenient for improving riding comfort performance. The thickness of the rim strip rubber 8 is maximized in the vicinity of the above-described exposed position of the interface, and gradually decreases from there to the outer side in the tire radial direction, and becomes substantially constant at the tire maximum width position 14 and the outer side in the tire radial direction. It has become. The thickness of the rim strip rubber 8 is measured along a direction perpendicular to the carcass layer 4.

  In the present embodiment, a step portion 15 is formed on the outer surface of the buttress region 2B. The step portion 15 is provided at a position corresponding to a fitting portion between the sector of the vulcanization mold and the side plate. When the upper end 8E is located on the outer side in the tire radial direction from the intersection of the normal extending perpendicularly to the carcass layer 4 through the apex of the step portion 15 and the outer surface of the carcass layer 4 (the main body ply), the upper end from the intersection The distance to 8E is preferably 5 mm or less.

  From the viewpoint of preventing the rigidity step from becoming excessively large at the upper end 6E of the side reinforcing layer 6, it is preferable that the upper end 6E is disposed 5 mm or more away from the upper end 1bE of the bead filler 1b outward in the tire radial direction. Further, from the viewpoint of suppressing deterioration in riding comfort performance, it is preferable that the upper end 6E of the side reinforcing layer 6 is disposed on the inner side in the tire radial direction than the tire maximum width position 14. With reference to the outer diameter position of the bead core 1a, the height Hs of the side reinforcing layer 6 is larger than the height Hb of the bead filler 1b and smaller than the height Hc of the carcass layer 4 (winding ply). The height Hs is set to 25 to 50% of the height Ht, for example.

  The dimensions of the tire T described above, such as the height Hr of the rim strip rubber 8, are measured in a no-load state in which the tire is mounted on a standard rim and filled with normal internal pressure. The rubber interface as shown in the figure can be specified in the tire cross section after vulcanization molding, and for example, by cutting the tire with a sharp blade, it can be discriminated by the property of the rubber interface observed thinly in the cross section. it can.

  The standard rim is a rim determined by each tire in the standard system including the standard on which the tire is based. For example, it is a standard rim for JATMA, "Design Rim" for TRA, or ETRTO. "Measuring Rim". The normal internal pressure is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based, the maximum air pressure for JATMA, and the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION for TRA" The maximum value described in "PRESSURES". If ETRTO, "INFLATION PRESSURE".

  The pneumatic tire of the present invention can be configured in the same manner as a normal pneumatic tire except that the rim strip rubber or the like is configured as described above, and any conventionally known material, shape, manufacturing method, etc. can be adopted in the present invention. . The structure such as the rim strip rubber described above may be applied to at least one side of the tire, but is preferably applied to both sides of the tire in order to enhance the improvement effect.

  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 illustrate the structure and effects of the present invention will be described. In the performance evaluations (1) and (2) below, tires of size 295 / 40R20 106Y were mounted on a rim of 20 × 10.5J, and the air pressure was 250 kPa.

(1) Ride comfort performance A tire was mounted on a vehicle (3000 cc class SUV) and traveled on a dry evaluation road surface, and a sensory evaluation was performed by a driver. The result of Comparative Example 1 is evaluated as an index with the value of 100, and the larger the value, the better the riding comfort performance.

(2) Steering stability performance A tire was mounted on a vehicle (3000 cc class SUV), traveled on an evaluation road surface, and a sensory evaluation by a driver was performed by performing turning, braking, and acceleration tests. The result of Comparative Example 1 is evaluated as an index with the value of 100, and the larger the value, the better the steering stability performance.

Comparative Examples 1-3 and Example 1
In the above-described embodiment, the height of the rim strip rubber and the like were changed to be Comparative Examples 1 to 3 and Example 1, respectively. In Comparative Example 1, the upper end of the rim strip rubber was positioned 20 mm away from the upper end of the side reinforcing layer inward in the tire radial direction. In Comparative Example 2, the upper end of the rim strip rubber was positioned 5 mm away from the upper end of the side reinforcing layer outward in the tire radial direction. In Comparative Example 3, the side reinforcing layer was not provided. In Example 1, the upper end of the rim strip rubber is located 20 mm away from the upper end of the side reinforcing layer in the tire radial direction, and the rolled-up end of the carcass layer matches the upper end of the rim strip rubber. Other tire configurations are common to the examples.

  As shown in Table 1, compared to Comparative Examples 1 to 3, Example 1 is superior in both steering stability performance and riding comfort performance.

DESCRIPTION OF SYMBOLS 1 Bead part 1a Bead core 1b Bead filler 1bE Upper end 2 of bead filler 2 Side wall part 2B Buttress area 3 Tread part 4 Carcass layer 4E Winding end of carcass layer 5 Tread rubber 6 Side reinforcing layer 6E Upper end 7 of side reinforcing layer Side wall rubber 8 Rim strip rubber 8E Upper end of rim strip rubber 14 Tire maximum width position 15 Step

Claims (6)

A carcass layer extending from the tread portion through the sidewall portion to the bead portion, a side reinforcing layer extending in the tire radial direction from the bead portion to the sidewall portion, and a side forming an outer surface of the sidewall portion Wall rubber and rim strip rubber forming the outer surface of the bead portion,
An annular bead core and a bead filler provided on the outer side in the tire radial direction of the bead core are embedded in the bead portion, and the carcass layer is wound up so as to sandwich them.
The upper end of the side reinforcing layer is disposed on the outer side in the tire radial direction than the upper end of the bead filler,
The rim strip rubber extends in the tire radial direction between the carcass layer and the sidewall rubber, and the upper end of the rim strip rubber is disposed on the outer side in the tire radial direction than the upper end of the side reinforcing layer. And
The pneumatic end of the carcass layer is disposed at the outer side in the tire radial direction from the upper end of the side reinforcing layer, and is close to the upper end of the rim strip rubber through a distance of 5 mm or less in the tire radial direction. tire.   The pneumatic tire according to claim 1, wherein a winding end of the carcass layer is close to an upper end of the rim strip rubber through a distance of 3 mm or less in a tire radial direction.   The pneumatic tire according to claim 1 or 2, wherein an upper end of the rim strip rubber is disposed 20 mm or more away from an upper end of the side reinforcing layer outward in a tire radial direction.   The pneumatic tire according to any one of claims 1 to 3, wherein an upper end of the side reinforcing layer is disposed 5 mm or more away from the upper end of the bead filler outward in the tire radial direction.   The pneumatic tire according to any one of claims 1 to 4, wherein a height of the rim strip rubber based on an outer diameter position of the bead core is 70% or more of a height of the tire outer diameter position.   The pneumatic tire according to any one of claims 1 to 5, wherein an upper end of the side reinforcing layer is disposed on the inner side in the tire radial direction from the tire maximum width position.

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