JP2020192835A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire that can reduce rolling resistance while suppressing deterioration in riding comfort.SOLUTION: A carcass layer 10 has a turn-up part 12 extending from an outer end part 32 of a bead core 31 toward a side wall part 8 while contacting a carcass main body part 11, where a tie rubber 40 is arranged between the carcass layer 10 and an inner liner 16. In the carcass layer 10, a height HR from a rim-diameter reference position BL to a turn-up edge part 12a is in a range of 10% or more and 50% or less of a tire cross section height SH. In the tie rubber 40, a tie rubber terminal part 41 is positioned closer to outside in a tire radial direction than the turn-up edge part 12a, and a height HQ of the tie rubber terminal part 41 from the rim-diameter reference position BL is in a range of 11% or more and 60% or less of the tire cross section height SH. A distance RQ between the turn-up edge part 12a and the tie rubber terminal part 41 is in a range of 1% or more and 30% or less of the tire cross section height SH.SELECTED DRAWING: Figure 3

Description

The present invention relates to a pneumatic tire.

In recent years, there has been an increasing demand for reducing the rolling resistance of pneumatic tires and reducing the weight of pneumatic tires for the purpose of improving fuel efficiency when the vehicle is running. For this reason, some conventional pneumatic tires are devised to reduce rolling resistance and weight. For example, in the pneumatic radial tire described in Patent Document 1, the tan δ of the tread rubber is set within a predetermined range, the rubber thickness of the tread portion and the sidewall portion is within a predetermined range, and the bead portion is set from the tread ground contact end. The rubber thickness in a predetermined range toward the side is defined to be thinner than the rubber thickness of the tread portion. Further, in the pneumatic tire described in Patent Document 2, a carcass ply reinforcing layer is arranged outside the carcass at the maximum width position of the tire in the tire width direction, and is embedded in the width of the carcass ply reinforcing layer and the carcass ply reinforcing layer. It specifies the angle of the reinforcing element. Further, in the pneumatic tire described in Patent Document 3, the height of the bead filler is specified. In Patent Documents 1 to 3, the rolling resistance is reduced by making these provisions.

Further, as one method for realizing weight reduction, weight reduction of the bead portion has been proposed. The techniques described in Patent Documents 4 to 6 are known as conventional pneumatic tires for reducing the weight of the bead portion. In Patent Documents 4 to 6, the weight of the pneumatic tire is reduced by omitting the bead filler.

Japanese Patent No. 3151035 Japanese Unexamined Patent Publication No. 2011-79469 Japanese Unexamined Patent Publication No. 2011-98597 Japanese Unexamined Patent Publication No. 9-109625 Japanese Unexamined Patent Publication No. 2008-149778 JP-A-2015-20741

Regarding rolling resistance, it is possible to reduce the rolling resistance by devising the structure of the pneumatic tire as in Patent Documents 1 to 3, and also by increasing the pressure of the air filled in the pneumatic tire. Rolling resistance can be reduced. However, when the air pressure is increased, the so-called vertical spring, which is the elasticity in the tire radial direction, increases, and there is a risk that the riding comfort during running of the vehicle deteriorates. Therefore, it has been very difficult to reduce the rolling resistance without deteriorating the riding comfort when the vehicle is running.

The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of reducing rolling resistance while suppressing deterioration of riding comfort.

In order to solve the above-mentioned problems and achieve the object, the pneumatic tire according to the present invention is formed in an annular shape extending in the tire circumferential direction, and has a tread portion having a tread rubber and both sides of the tread portion. A pair of sidewall portions arranged, a pair of bead portions arranged inside each of the pair of sidewall portions in the tire radial direction, a bead core disposed on the bead portion, and a pair of the beads. A carcass layer bridged between the portions and an inner liner arranged on the inner surface of the tire along the carcass layer are provided, and the carcass layer includes a carcass body portion bridged between the pair of bead portions. It is formed continuously from the carcass main body, is folded back from the inside in the tire width direction to the outside in the tire width direction along the peripheral edge of the bead core, and comes into contact with the carcass main body from the position of the outer end portion in the tire radial direction of the bead core. However, it has a turn-up portion extending toward the sidewall portion side, and a tie rubber is disposed between the carcass layer located on the sidewall portion and the inner liner, and the carcass layer is provided. The height in the tire radial direction from the reference position on the inner side of the tire cross-sectional height in the tire radial direction to the turn-up edge portion which is the outer end of the turn-up portion in the tire radial direction is the tire cross-sectional height. Within the range of 10% or more and 50% or less, the tie rubber terminal portion, which is the inner end portion in the tire radial direction, is located outside the turn-up edge portion in the tire radial direction, and is from the reference position. The height of the tie rubber terminal portion in the tire radial direction is within the range of 11% or more and 60% or less of the tire cross-sectional height, and the distance between the turn-up edge portion and the tie rubber terminal portion is the tire cross section. It is characterized in that it is within the range of 1% or more and 30% or less of the height.

Further, in the pneumatic tire, it is preferable that the tread radius of the tread portion in the tire meridional cross section is in the range of 600 mm or more and 1700 mm or less.

Further, in the pneumatic tire, the ground contact width is preferably in the range of 60% or more and 90% or less of the maximum tire width.

Further, in the pneumatic tire, the height in the tire radial direction from the reference position to the maximum width position of the tire is preferably in the range of 50% or more and 60% or less with respect to the cross-sectional height of the tire.

Further, in the pneumatic tire, it is preferable that the thickness of the side rubber located outside the carcass layer in the tire width direction at the tire maximum width position is within the range of 1 mm or more and 4 mm or less.

Further, in the pneumatic tire, the tread rubber has a thickness Gc at the center position and a thickness Gs at the shoulder position satisfying the relationship of Gc ≧ Gs, and the thickness Gc at the center position and the shoulder. It is preferable that the thickness Gs at the position is within the range of 2% or more and 10% or less of the cross-sectional height of the tire, respectively.

The pneumatic tire according to the present invention has an effect that rolling resistance can be reduced while suppressing deterioration of riding comfort.

FIG. 1 is a cross-sectional view of the meridian showing a main part of the pneumatic tire according to the embodiment. FIG. 2 is a detailed view of the sidewall portion and the bead portion shown in FIG. FIG. 3 is a detailed view of the bead portion shown in FIG. FIG. 4 is a detailed view of the bead core shown in FIG. FIG. 5 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view when the bead wires are laminated in six layers. FIG. 6 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view of a modified example in which bead wires are laminated in five layers. FIG. 7 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory view of a modified example in which bead wires are laminated in six layers. FIG. 8A is a chart showing the results of the performance evaluation test of the pneumatic tire. FIG. 8B is a chart showing the results of the performance evaluation test of the pneumatic tire.

Hereinafter, embodiments of the pneumatic tire according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, the components in the following embodiments include those that can be easily conceived by those skilled in the art, or those that are substantially the same.

[Embodiment]
In the following description, the tire radial direction refers to a direction orthogonal to the tire rotation axis (not shown) which is the rotation axis of the pneumatic tire 1, and the inside in the tire radial direction is the side facing the tire rotation axis in the tire radial direction. The outer side in the tire radial direction means the side away from the tire rotation axis in the tire radial direction. The tire circumferential direction refers to a circumferential direction centered on the tire rotation axis. The tire width direction means a direction parallel to the tire rotation axis, the inside in the tire width direction is the side toward the tire equatorial plane (tire equatorial line) CL in the tire width direction, and the outside in the tire width direction is the tire width direction. Refers to the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane that is orthogonal to the tire rotation axis and passes through the center of the tire width of the pneumatic tire 1, and the tire equatorial plane CL is a tire that is the center position in the tire width direction of the pneumatic tire 1. The position in the width direction coincides with the center line in the width direction. The tire width is the width of the outermost portions in the tire width direction in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equatorial line is a line on the tire equatorial plane CL along the tire circumferential direction of the pneumatic tire 1. Further, in the following description, the tire meridional cross section means a cross section when the tire is cut on a plane including the tire rotation axis.

FIG. 1 is a cross-sectional view of the meridian showing a main part of the pneumatic tire 1 according to the embodiment. The pneumatic tire 1 according to the present embodiment is provided with a tread portion 2 extending in the tire circumferential direction and forming an annular shape at the outermost portion in the tire radial direction when viewed in the tire meridional cross section. The tread portion 2 has a tread rubber 4 made of a rubber composition. Further, the surface of the tread portion 2, that is, the portion that comes into contact with the road surface when the vehicle (not shown) equipped with the pneumatic tire 1 is running is formed as a ground contact surface 3, and the ground contact surface 3 is the pneumatic tire 1. It forms part of the contour. The tread portion 2 is formed with a plurality of circumferential grooves 25 extending in the tire circumferential direction and a plurality of lug grooves (not shown) extending in the tire width direction on the ground contact surface 3, and these circumferential grooves 25 and lug grooves are formed. As a result, a plurality of land portions 20 are defined on the surface of the tread portion 2.

The circumferential groove 25 may extend linearly in the tire circumferential direction, or may be provided in a wavy shape or a zigzag shape that extends in the tire circumferential direction and oscillates in the tire width direction. The lug groove may also extend linearly in the tire width direction, and may be inclined in the tire circumferential direction while extending in the tire width direction, or may be curved or bent in the tire circumferential direction while extending in the tire width direction. It may be formed.

Further, the tread rubber 4 included in the tread portion 2 has a cap rubber 4a forming the ground contact surface 3 and a base rubber 4b located inside the cap rubber 4a in the tire radial direction. That is, the tread portion 2 is formed by laminating the cap rubber 4a and the base rubber 4b in the tire radial direction. The cap rubber 4a and the base rubber 4b have a tan δ of 0.3 or less at 60 ° C.

The tan δ referred to here is based on JIS-K6394, using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho) under the conditions of frequency 20 Hz, initial strain 10%, dynamic strain ± 2%, and temperature 60 ° C. Is measured.

Shoulder portions 5 are located at both outer ends of the tread portion 2 in the tire width direction, and a pair of sidewall portions 8 are arranged inside the shoulder portion 5 in the tire radial direction. That is, the pair of sidewall portions 8 are arranged on both sides of the tread portion 2 in the tire width direction, in other words, the sidewall portions 8 are arranged at two locations on both sides of the pneumatic tire 1 in the tire width direction. ing. The sidewall portion 8 formed in this way is a portion of the pneumatic tire 1 exposed to the outermost side in the tire width direction, and has a side rubber 9 which is a rubber material.

A bead portion 30 is arranged inside each of the pair of sidewall portions 8 in the tire radial direction. Similar to the sidewall portion 8, the bead portions 30 are arranged at two locations on both sides of the tire equatorial plane CL, that is, a pair of bead portions 30 are arranged on both sides of the tire equatorial plane CL in the tire width direction. Has been done. Further, each bead portion 30 is provided with a bead core 31.

Further, a belt layer 14 is provided inside the tread portion 2 in the tire radial direction. In the belt layer 14, a pair of intersecting belts 141 and 142 and a belt cover 143 are laminated. The pair of crossing belts 141 and 142 are formed by coating a plurality of belt cords made of steel or an organic fiber material such as polyester, rayon or nylon with coated rubber and rolling them, and the inclination angle of the belt cord with respect to the tire circumferential direction. The belt angle defined as is within a predetermined range (for example, 20 ° or more and 55 ° or less). Further, the pair of crossing belts 141 and 142 have different belt angles. Therefore, the pair of crossing belts 141 and 142 are configured as a so-called cross-ply structure in which the belt cords are laminated so as to intersect each other in the inclination direction.

The belt cover 143 is formed by coating a belt cover cord made of steel or an organic fiber material such as polyester, rayon, or nylon with a coated rubber, and a belt angle defined as an inclination angle of the belt cord with respect to the tire circumferential direction is predetermined. It is within the range of (for example, 0 ° or more and 10 ° or less). In the present embodiment, the belt cover 143 is arranged so as to cover the entire pair of crossing belts 141 and 142. Further, the pair of belt covers 143 is, for example, a strip material formed by coating one or a plurality of belt cover cords with coated rubber, and the strip material is applied to the outer peripheral surfaces of the cross belts 141 and 142 in the tire circumferential direction. It is composed by winding it multiple times and spirally. Further, the belt cover 143 may have a configuration other than this. The belt cover 143 may be arranged only near the end portion of the pair of crossing belts 141 and 142 in the tire width direction, or the belt cover 143 covering the entire crossing belts 141 and 142 and the crossing belt 141, A belt cover 143 arranged only near the end portion of 142 in the tire width direction may be laminated.

A carcass layer 10 containing a radial ply cord is continuously provided on the inner side of the belt layer 14 in the tire radial direction and on the CL side of the tire equatorial plane of the sidewall portion 8. Therefore, the pneumatic tire 1 according to the present embodiment is configured as a so-called radial tire. The carcass layer 10 has a single-layer structure composed of one carcass ply or a multi-layer structure formed by laminating a plurality of carcass plies, and is toroidal between a pair of bead portions 30 arranged on both sides in the tire width direction. It is laid out in a shape to form the skeleton of the tire.

Specifically, the carcass layer 10 is arranged from one bead portion 30 to the other bead portion 30 of the pair of bead portions 30 located on both sides in the tire width direction, and the vicinity of both ends of the carcass layer 10 is arranged. , The bead portion 30 is rewound along the bead core 31 outward in the tire width direction so as to wrap the bead core 31. Therefore, the carcass layer 10 is folded back while being bent along the peripheral edge of the bead core 31 and the carcass main body 11 bridged between the pair of bead portions 30, and the outer end of the bead core 31 in the tire radial direction. It is composed of a turn-up portion 12 extending from the position of the portion 32 toward the sidewall portion 8 side while contacting the carcass main body portion 11. Of these, the turn-up portion 12 is formed continuously from the carcass main body portion 11 and is located at the position where the bead core 31 is arranged in the bead portion 30, from the inside in the tire width direction to the tire width direction along the peripheral edge of the bead core 31. It is folded back toward the outside.

Further, the belt layer 14 is arranged on the outer side in the tire radial direction of the portion located at the tread portion 2 in the carcass layer 10 thus bridged between the pair of bead portions 30. Further, the carcass ply of the carcass layer 10 is formed by coating a plurality of carcass cords made of steel or an organic fiber material such as aramid, nylon, polyester and rayon with a coated rubber and rolling them. The carcass cords constituting the carcass ply are arranged so that the carcass angle defined as the inclination angle of the carcass cord in the longitudinal direction with respect to the tire circumferential direction is within the range of 80 ° or more and 90 ° or less, and a plurality of carcass cords are arranged side by side. ing.

A rim cushion rubber 17 forming a contact surface of the bead portion 30 with respect to the rim flange is arranged on the inner side in the tire radial direction and the outer side in the tire width direction of the turn-up portion 12 of the bead core 31 and the carcass layer 10 in the bead portion 30. There is.

Further, an inner liner 16 is arranged along the carcass layer 10 on the inside of the carcass layer 10 or on the inner side of the carcass layer 10 in the pneumatic tire 1. The inner liner 16 is an air permeation prevention layer that is arranged on the inner surface 18 of the tire and covers the carcass layer 10, suppresses oxidation due to exposure of the carcass layer 10, and prevents leakage of air filled in the tire. Further, the inner liner 16 is composed of a rubber composition containing butyl rubber as a main component. As the rubber composition containing butyl rubber as a main component, for example, butyl rubber (IIR), butyl rubber and the like can be adopted. The butyl rubber is preferably a halogenated butyl rubber such as chlorinated butyl rubber (Cl-IIR) or brominated butyl rubber (Br-IIR).

Further, a tie rubber 40 is arranged between the carcass layer 10 and the inner liner 16. The tie rubber 40 disposed between the carcass layer 10 and the inner liner 16 is for suppressing the carcass cord from biting into the inner liner 16 when inflating the unvulcanized pneumatic tire 1 during tire manufacturing. This layer contributes to air permeation prevention and steering stability on a dry road surface in the manufactured pneumatic tire 1. The tie rubber 40 is arranged between the carcass layer 10 located at least in the sidewall portion 8 and the inner liner 16, and in the present embodiment, the tie rubber 40 passes through the tread portion 2 and the sidewalls on both sides in the tire width direction. It is arranged between the portions 8.

Further, in the pneumatic tire 1 according to the present embodiment, the tread radius TR of the tread portion 2 in the tire meridional cross section is within the range of 600 mm or more and 1700 mm or less, and when compared with the tire outer diameter, the tread radius TR is , It is within the range of 100% or more and 140% or less of the tire outer diameter. That is, the tread portion 2 has a profile that serves as a reference for the ground plane 3 and is formed in a relatively flat shape. In this case, the tread radius TR sets the radius of the ground contact surface 3 of the tread portion 2 in the direction along the cross section of the tire meridian as a radius ruler with the pneumatic tire 1 assembled on the regular rim and filled with the regular internal pressure. It is the value measured by.

The regular rim referred to here is a "standard rim" specified by JATTA, a "Design Rim" specified by TRA, or a "Measuring Rim" specified by ETRTO. The normal internal pressure is the "maximum air pressure" specified by JATTA, the maximum value described in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or "INFLATION PRESSURES" specified by ETRTO. Further, the tread radius TR is preferably in the range of 800 mm or more and 1500 mm or less, and when compared with the tire outer diameter, it is preferably in the range of 110% or more and 130% or less of the tire outer diameter.

Further, the tread portion 2 has a ground contact width TW within a range of 60% or more and 90% or less of the maximum tire width SW. The ground contact width TW referred to here is the distance between the ground contact ends T of the ground contact surface 3 in the tire width direction. The ground contact end T is in contact with the pneumatic tire 1 when it is rim-assembled on a regular rim to fill the regular internal pressure, placed perpendicular to the flat plate in a stationary state, and applied with a load corresponding to the regular load. Both outermost ends in the tire width direction of the region in contact with the flat plate on the ground 3 are continuous in the tire circumferential direction. The normal load here is the "maximum load capacity" specified by JATTA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or the "LOAD CAPACITY" specified by ETRTO.

Further, the maximum tire width SW referred to here is a sidewall portion when the pneumatic tire 1 is rim-assembled on a regular rim, the regular internal pressure is applied, and no load is applied to the pneumatic tire 1. The width in the tire width direction is the position where the dimension in the tire width direction is maximized excluding the structure protruding from the outer surface of No. 8. Further, the ground contact width TW is preferably in the range of 70% or more and 80% or less of the maximum tire width SW.

Further, in the pneumatic tire 1 according to the present embodiment, the height HW in the tire radial direction from the reference position inside the tire cross-sectional height SH in the tire radial direction to the tire maximum width position W is different from the tire cross-sectional height SH. It is within the range of 50% or more and 60% or less. The tire cross-sectional height SH referred to here is the distance in the tire radial direction between the portion of the tread portion 2 located on the outermost side in the tire radial direction and the rim diameter reference position BL. That is, the tire cross-sectional height SH is the tire outer diameter and the rim when the pneumatic tire 1 is rim-assembled on the regular rim, the regular internal pressure is applied, and no load is applied to the pneumatic tire 1. It means 1/2 of the difference from the diameter. Therefore, the reference position on the inner side of the tire cross-sectional height SH in the tire radial direction is the rim diameter reference position BL, and the tire from the reference position on the inner side of the tire cross-sectional height SH in the tire radial direction to the tire maximum width position W. The height HW in the radial direction is the distance in the tire radial direction from the rim diameter reference position BL to the tire maximum width position W. Further, the tire maximum width position W is a position in the tire radial direction at a position where the tire maximum width SW is obtained.

The height HW in the tire radial direction from the rim diameter reference position BL to the tire maximum width position W is preferably in the range of 52% or more and 56% or less with respect to the tire cross-sectional height SH.

Further, in the tread rubber 4 included in the tread portion 2, the thickness Gc at the center position and the thickness Gs at the shoulder position satisfy the relationship of Gc ≧ Gs. The thickness Gc at the center position and the thickness Gs at the shoulder position referred to here are the combined thickness of the laminated cap rubber 4a and the base rubber 4b.

Of these thicknesses of the tread rubber 4, the thickness Gc at the center position is the thickness of the tread rubber 4 measured in the normal direction of the ground contact surface 3 on the tire equatorial plane CL. That is, in the present embodiment, the thickness Gc of the tread rubber 4 at the center position is the contact patch 3 side of the belt cover 143 in the normal direction of the contact patch 3 passing through the intersection of the contact patch 3 and the tire equatorial plane CL. It is the distance between the surface and the ground plane 3. The thickness Gs at the shoulder position is the thickness of the tread rubber 4 measured in the normal direction of the ground contact surface 3 passing through the intersection of the ground contact surface 3 and the ground contact end T. That is, in the present embodiment, the thickness GS of the tread rubber 4 at the shoulder position is the surface of the belt cover 143 on the ground surface 3 side in the normal direction of the ground surface 3 passing through the intersection of the ground surface 3 and the ground end T. Is the distance between the tread and the ground plane 3.

When the circumferential groove 25 is arranged on the tire equatorial plane CL, the thickness Gc of the tread rubber 4 at the center position is the method of the ground contact surface 3 at the position closest to the tire equatorial plane CL on the ground contact surface 3. It is the thickness of the tread rubber 4 measured in the linear direction.

Further, the thickness Gc at the center position and the thickness Gs at the shoulder position of the tread rubber 4 are within the range of 2% or more and 10% or less of the tire cross-sectional height SH, respectively. Further, the thickness Gc at the center position and the thickness Gs at the shoulder position of the tread rubber 4 are each within the range of 3 mm or more and 13 mm or less. The thickness Gc at the center position and the thickness Gs at the shoulder position of the tread rubber 4 are preferably in the range of 3% or more and 7% or less of the tire cross-sectional height SH, respectively, and are 5 mm or more and 10 mm or less, respectively. It is preferably within the range.

FIG. 2 is a detailed view of the sidewall portion 8 and the bead portion 30 shown in FIG. The thickness of the side rubber 9 of the sidewall portion 8 is relatively thin. Specifically, the thickness Gw of the side rubber 9 located outside the carcass layer 10 in the tire width direction at the maximum tire width position W is 1 mm. It is within the range of 4 mm or less. The thickness Gw of the side rubber 9 at the maximum tire width position W is preferably in the range of 2 mm or more and 3 mm or less.

Further, the turn-up portion 12 of the carcass layer 10 has a height HR in the tire radial direction from the rim diameter reference position BL to the turn-up edge portion 12a, which is the outer end portion of the turn-up portion 12 in the tire radial direction. The cross-sectional height SH is within the range of 10% or more and 50% or less. That is, in the turn-up portion 12, the relationship between the height HR in the tire radial direction from the rim diameter reference position BL to the turn-up edge portion 12a and the tire cross-sectional height SH is 0.10 ≦ (HR / SH) ≦. It is within the range of 0.50. The height HR of the turn-up portion 12 in the tire radial direction from the rim diameter reference position BL to the turn-up edge portion 12a is within the range of 20% or more and 30% or less with respect to the tire cross-sectional height SH. Is preferable.

FIG. 3 is a detailed view of the bead portion 30 shown in FIG. In the carcass layer 10, the turn-up width Ht, which is the distance between the outer end portion 32 of the bead core 31 and the turn-up edge portion 12a, is within the range of 10% or more and 60% or less of the tire cross-sectional height SH. In this case, the turn-up width Ht is parallel to the turn-up portion inner reference line Lui through the turn-up edge portion 12a, with the normal line of the carcass layer 10 passing through the outer end portion 32 of the bead core 31 as the turn-up portion inner reference line Li. This is the distance between the turn-up portion inner reference line Lui and the turn-up portion outer reference line Luo when the line is the turn-up portion outer reference line Luo. The turn-up portion inner reference line Lii is specifically the normal line of the carcass main body portion 11 passing through the outer end portion 32 of the bead core 31.

The tie rubber 40 disposed between the carcass layer 10 and the inner liner 16 has a tie rubber terminal 41, which is an inner end in the tire radial direction, at a position in the tire radial direction of the turn-up edge portion 12a of the turn-up portion 12. It is located outside the tire radial direction. Therefore, the tie rubber 40 is arranged on the tire inner surface 18 side of the carcass main body 11 without overlapping with the turn-up portion 12.

In the tie rubber 40 in which the tie rubber terminal portion 41 is located outside the turn-up edge portion 12a in the tire radial direction, the height HQ of the tie rubber terminal portion 41 in the tire radial direction from the rim diameter reference position BL is the tire cross-sectional height SH. It is in the range of 11% or more and 60% or less. That is, in the tie rubber 40, the relationship between the height HQ in the tire radial direction from the rim diameter reference position BL to the tie rubber terminal portion 41 and the tire cross-sectional height SH is 0.11 ≦ (HQ / SH) ≦ 0.60. It is within the range of. The height HQ of the tie rubber 40 from the rim diameter reference position BL to the tie rubber terminal portion 41 in the tire radial direction is preferably in the range of 30% or more and 50% or less with respect to the tire cross-sectional height SH.

Further, since the tie rubber 40 does not overlap with the turn-up portion 12, the distance RQ between the turn-up edge portion 12a separated from each other and the tie rubber terminal portion 41 is 1% or more and 30% or less of the tire cross-sectional height SH. It is within the range. That is, the relationship between the distance RQ between the turn-up edge portion 12a and the tie rubber terminal portion 41 and the tire cross-sectional height SH is within the range of 0.01 ≦ (RQ / SH) ≦ 0.30. The distance RQ between the turn-up edge portion 12a and the tie rubber terminal portion 41 is within the range of 0.1 mm or more and 30 mm or less in this embodiment. Further, the distance RQ between the turn-up edge portion 12a and the tie rubber terminal portion 41 with respect to the tire cross-sectional height SH is preferably in the range of 10% or more and 20% or less.

The bead core 31 arranged in the bead portion 30 is composed of at least one bead wire 33 wound in the tire circumferential direction, and at least one row in which a plurality of peripheral portions of the bead wire 33 are arranged in the tire width direction in the tire meridional cross section. And a plurality of layers overlapping in the tire radial direction are formed. The bead core 31 may have a so-called single-winding structure in which a single bead wire 33 is continuously wound as long as a plurality of peripheral portions of the bead wire 33 form a row and a layer in the tire meridional cross section. Often, it may have a so-called layer winding structure in which a plurality of bead wires 33 are wound in a aligned state. In the present embodiment, a layer including three rows of orbital portions, a layer including four rows of orbital portions, a layer including three rows of orbital portions, a layer including two rows of orbital portions, and one row in order from the innermost side in the tire radial direction. It has a structure in which a total of 5 layers including the peripheral portion of the above are laminated. In the following description, such a laminated structure of bead wires 33 will be referred to as a "3 + 4 + 3 + 2 + 1 structure". Similarly, in the following description, the laminated structure of the bead wires 33 is expressed in the same form in which the number of rows included in each layer is connected by “+” in order from the innermost layer in the tire radial direction. Further, in the present embodiment, in the bead core 31, the bead wires 33 are stacked in a bale shape. In this case, "bale stacking" is a stacking method in which the centers of three orbital portions in contact with each other form a substantially equilateral triangle, and is a laminated structure having a high filling rate, which is sometimes called a hexagonal packing arrangement. Is.

FIG. 4 is a detailed view of the bead core 31 shown in FIG. Assuming that the bead core 31 has a polygon formed by common tangents of a plurality of circumferential portions of the bead wire 33 in the tire meridional cross section as the outer shape 34 of the bead core 31, this outer shape 34 has a single apex 35 on the outer side in the tire radial direction. And has a base 36 on the inner side in the tire radial direction so as to face the apex 35. That is, in the present embodiment, the bead core 31 has a pentagonal outer shape 34 because the bead wire 33 has a 3 + 4 + 3 + 2 + 1 structure. Further, the bead core 31 has an acute angle θ1 formed by two sides sandwiching the apex 35 of the outer shape 34, and the bead core 31 as a whole is tapered so that the width gradually narrows from the portion having the maximum width toward the outside in the tire radial direction. It is formed in a shape. In the following description, such a shape of the bead core 31 is referred to as an "outer diameter side wedge shape". Further, since the apex 35 of the outer shell shape 34 is located on the outermost side of the bead core 31 in the tire radial direction, the apex 35 of the outer shell shape 34 is the outer end portion 32 of the bead core 31 in the tire radial direction.

Since the bead core 31 is formed in a wedge shape on the outer diameter side, the carcass layer 10 folded around the bead core 31 bends along the peripheral edge of the bead core 31. That is, since the bead core 31 has a substantially pentagonal shape in the tire meridional cross section, the carcass layer 10 extending along the peripheral edge of the bead core 31 is also bent into a substantially pentagonal shape. Further, in the turn-up portion 12 of the carcass layer 10, the portion outside the tire radial direction of the bead core 31 is in contact with the carcass body portion 11 of the carcass layer 10 and is in contact with the carcass body portion of the carcass layer 10. It extends along the 11 toward the sidewall portion 8 side. Therefore, in the bead portion 30, a closed region surrounding the bead core 31 is formed by the carcass main body portion 11 and the turn-up portion 12 of the carcass layer 10.

In the closed region formed by the carcass main body portion 11 and the turn-up portion 12 of the carcass layer 10, only the bead core 31 is substantially present. Therefore, the pneumatic tire 1 according to the present embodiment includes a bead filler as used in a conventional pneumatic tire or a similar tire component (carcass of the carcass layer 10 arranged on the outer side of the bead core 31 in the tire radial direction). A member that is wrapped by the main body portion 11 and the turn-up portion 12 to increase the rigidity from the bead portion 30 to the sidewall portion 8) is not arranged. That is, in the pneumatic tire 1, there is an insulation rubber that covers the bead wire 33 and a rubber that fills a slight gap formed between the bead core 31 and the carcass layer 10 in the closed region. No bead filler with a large volume like the pneumatic tires of. In the pneumatic tire 1 according to the present embodiment, the ratio (a / A × 100%) of the total area a of the rubber existing in the closed region to the area A of the closed region in the tire meridional cross section is the rubber occupancy ratio of the closed region. Then, the rubber occupancy rate is in the range of 0.1% or more and 15% or less.

When the pneumatic tire 1 according to the present embodiment is mounted on the vehicle, the pneumatic tire 1 is assembled to the rim wheel by fitting the rim wheel to the bead portion 30, and the inside is filled with air. Install it on the vehicle in a frayed state. When a vehicle equipped with the pneumatic tire 1 travels, the pneumatic tire 1 rotates while the contact patch 3 of the lower portion of the contact patch 3 comes into contact with the road surface. The vehicle travels by transmitting a driving force and a braking force to the road surface and generating a turning force by the frictional force between the ground contact surface 3 and the road surface.

For example, when traveling on a dry road surface with a vehicle equipped with pneumatic tires 1, the driving force and braking force are transmitted to the road surface or turning force mainly by the frictional force between the ground contact surface 3 and the road surface. It runs by generating. Further, when traveling on a wet road surface, water between the ground contact surface 3 and the road surface enters a groove such as a circumferential groove 25, and the water between the ground contact surface 3 and the road surface is drained through these grooves. While driving. As a result, the ground contact surface 3 can easily touch the road surface, and the frictional force between the ground contact surface 3 and the road surface enables the vehicle to travel as desired.

Further, in the pneumatic tire 1 according to the present embodiment, since the tan δ of the cap rubber 4a constituting the ground contact surface 3 of the tread portion 2 at 60 ° C. is 0.3 or less, the tread portion 2 of the tread portion 2 is running. Heat generation can be suppressed and rolling resistance can be reduced.

Further, since the thickness of the side rubber 9 of the sidewall portion 8 is thin, the spring constant of the pneumatic tire 1 in the tire radial direction can be reduced, and the so-called vertical spring can be reduced. As a result, the sidewall portion 8 can be easily bent, and the riding comfort during traveling of the vehicle can be ensured. In particular, even when the pressure of the air filled in the pneumatic tire 1 is increased for the purpose of reducing rolling resistance, it is possible to suppress an increase in the vertical spring and prevent deterioration of riding comfort when the vehicle is running. be able to.

Further, by reducing the thickness of the side rubber 9 to make the sidewall portion 8 easier to bend, the sidewall portion 8 can be made easier to bend when a load is applied, and the pneumatic tire 1 can be easily bent by the load load when the vehicle is running. The contribution rate of the sidewall portion 8 at the time of deformation can be increased. As a result, the energy loss in the tread portion 2 when the pneumatic tire 1 is deformed by the load can be relatively reduced, so that the rolling resistance can be reduced.

Further, in the tie rubber 40, since the tie rubber terminal portion 41 is located outside the turn-up edge portion 12a in the tire radial direction, the tie rubber terminal portion 41 is located inside the turn-up edge portion 12a in the tire radial direction with the tie rubber 40. Compared with the case where the turn-up portion 12 overlaps, the rigidity in the vicinity of the bead portion 30 can be reduced. As a result, the vertical spring in the vicinity of the bead portion 30 can be reduced, and it is possible to more reliably suppress the deterioration of the riding comfort when the vehicle is running.

Further, the carcass layer 10 has a bead portion because the height HR in the tire radial direction from the rim diameter reference position BL to the turn-up edge portion 12a is within the range of 10% or more and 50% or less of the tire cross-sectional height SH. The vertical spring can be effectively reduced while ensuring the rigidity in the vicinity of 30. That is, when the height HR from the rim diameter reference position BL to the turn-up edge portion 12a is less than 10% of the tire cross-sectional height SH, the height HR from the rim diameter reference position BL to the turn-up edge portion 12a Is too low, there is a risk that the rigidity in the vicinity of the bead portion 30 will be insufficient. In this case, the range applied from the sidewall portion 8 to the bead portion 30 may be excessively bent when a load is applied, and the range applied from the sidewall portion 8 to the bead portion 30 is excessively bent when the vehicle is running, thereby causing rolling resistance. It may be difficult to reduce. If the height HR from the rim diameter reference position BL to the turn-up edge portion 12a exceeds 50% of the tire cross-sectional height SH, the height HR from the rim diameter reference position BL to the turn-up edge portion 12a is Since it is too high, it may be difficult to effectively reduce the vertical spring. In this case, since the sidewall portion 8 is less likely to bend, it may be difficult to secure a comfortable ride when the vehicle is traveling.

On the other hand, when the height HR from the rim diameter reference position BL to the turn-up edge portion 12a is within the range of 10% or more and 50% or less of the tire cross-sectional height SH, the rigidity in the vicinity of the bead portion 30 is secured. At the same time, the vertical spring can be effectively reduced. As a result, the rolling resistance can be reduced and the riding comfort when the vehicle is running can be ensured.

Further, since the height HQ of the tie rubber 40 from the rim diameter reference position BL to the tie rubber terminal portion 41 in the tire radial direction is within the range of 11% or more and 60% or less of the tire cross-sectional height SH, the vicinity of the bead portion 30 The vertical spring can be effectively reduced while ensuring the rigidity of the tire. That is, when the height HQ from the rim diameter reference position BL to the tie rubber terminal portion 41 is less than 11% of the tire cross-sectional height SH, the height HQ from the rim diameter reference position BL to the tie rubber terminal portion 41 is low. Therefore, even if the tie rubber terminal portion 41 is positioned outside the turn-up edge portion 12a in the tire radial direction, it may be difficult to effectively reduce the vertical spring. In this case, since the sidewall portion 8 is less likely to bend, it may be difficult to secure a comfortable ride when the vehicle is traveling. If the height HQ from the rim diameter reference position BL to the tie rubber terminal 41 exceeds 60% of the tire cross-sectional height SH, the height HQ from the rim diameter reference position BL to the tie rubber terminal 41 is too high. Therefore, the rigidity in the vicinity of the bead portion 30 may be insufficient. In this case, the range applied from the sidewall portion 8 to the bead portion 30 may be excessively bent when a load is applied, and the range applied from the sidewall portion 8 to the bead portion 30 is excessively bent when the vehicle is running, thereby causing rolling resistance. It may be difficult to reduce. Further, when the height HQ from the rim diameter reference position BL to the tie rubber terminal portion 41 is too high and the tie rubber terminal portion 41 is too close to the belt layer 14, stress concentration is likely to occur in the vicinity of the tie rubber terminal portion 41. There is a risk of becoming. In this case, there is a possibility that a failure is likely to occur in the vicinity of the tie rubber terminal portion 41 due to stress concentration.

On the other hand, when the height HQ from the rim diameter reference position BL to the tie rubber terminal portion 41 is within the range of 11% or more and 60% or less of the tire cross-sectional height SH, the rigidity in the vicinity of the bead portion 30 is secured. At the same time, the vertical spring can be effectively reduced, and the occurrence of failure in the vicinity of the tie rubber terminal portion 41 can be suppressed. As a result, the rolling resistance can be reduced and the riding comfort when the vehicle is running can be ensured.

Further, since the distance RQ between the turn-up edge portion 12a and the tie rubber terminal portion 41 is within the range of 1% or more and 30% or less of the tire cross-sectional height SH, the vertical spring is maintained while ensuring the rigidity in the vicinity of the bead portion 30. Can be effectively reduced. That is, when the distance RQ between the turn-up edge portion 12a and the tie rubber terminal portion 41 is less than 1% of the tire cross-sectional height SH, the distance RQ between the turn-up edge portion 12a and the tie rubber terminal portion 41 is too small. Even if the tie rubber terminal portion 41 is located outside the turn-up edge portion 12a in the tire radial direction, it is difficult to reduce the rigidity in the vicinity of the bead portion 30 as compared with the case where the tie rubber 40 and the turn-up portion 12 overlap. There is a risk of becoming. In this case, since it is difficult to reduce the vertical spring near the bead portion 30, it may be difficult to suppress the deterioration of riding comfort when the vehicle is running. Further, when the distance RQ between the turn-up edge portion 12a and the tie rubber terminal portion 41 exceeds 30% of the tire cross-sectional height SH, the distance RQ between the turn-up edge portion 12a and the tie rubber terminal portion 41 is too large. There is a risk that the rigidity near the bead portion 30 will be insufficient. In this case, the range applied from the sidewall portion 8 to the bead portion 30 may be excessively bent when a load is applied, and the range applied from the sidewall portion 8 to the bead portion 30 is excessively bent when the vehicle is running, thereby causing rolling resistance. It may be difficult to reduce.

On the other hand, when the distance RQ between the turn-up edge portion 12a and the tie rubber terminal portion 41 is within the range of 1% or more and 30% or less of the tire cross-sectional height SH, while ensuring the rigidity in the vicinity of the bead portion 30. , The vertical spring can be effectively reduced. As a result, the rolling resistance can be reduced and the riding comfort when the vehicle is running can be ensured. As a result, rolling resistance can be reduced while suppressing deterioration of riding comfort.

Further, since the tread radius TR of the tread portion 2 in the tire meridional cross section is within the range of 600 mm or more and 1700 mm or less, the ground contact area when the ground contact surface 3 touches the ground can be secured with an appropriate size. That is, when the tread radius TR of the tread portion 2 is less than 600 mm, the tread radius TR is too small, so that the deformation of the tread portion 2 when the ground contact surface 3 touches the ground may become too large. In this case, the rolling resistance tends to increase as the tread portion 2 is significantly deformed, so that it may be difficult to reduce the rolling resistance. Further, when the tread radius TR of the tread portion 2 is larger than 1700 mm, the tread radius TR is too large, so that the ground contact area when the ground contact surface 3 touches the ground becomes too large, and it becomes difficult to effectively reduce the rolling resistance. There is a risk.

On the other hand, when the tread radius TR of the tread portion 2 is within the range of 600 mm or more and 1700 mm or less, the ground contact area when the ground contact surface 3 touches the ground can be secured with an appropriate size. As a result, the rolling resistance can be reduced more reliably.

Further, since the ground contact width TW of the tread portion 2 is within the range of 60% or more and 90% or less of the maximum tire width SW, the size of the ground contact width TW with respect to the maximum tire width SW should be secured at an appropriate size. Can be done. That is, when the ground contact width TW of the tread portion 2 is less than 60% of the tire maximum width SW, the ground contact width TW is too small with respect to the tire maximum width SW, so that the contact width TW changes when the load changes. There is a risk that it will grow easily. In this case, it may be difficult to reduce the rolling resistance due to a large change in the ground contact width TW. Further, when the ground contact width TW of the tread portion 2 is larger than 90% of the tire maximum width SW, the ground contact width TW is too large with respect to the tire maximum width SW, so that it may be difficult to effectively reduce the rolling resistance. is there.

On the other hand, when the ground contact width TW of the tread portion 2 is within the range of 60% or more and 90% or less of the maximum tire width SW, the size of the ground contact width TW with respect to the maximum tire width SW is set to an appropriate size. Can be secured. As a result, the rolling resistance can be reduced more reliably.

Further, since the height HW in the tire radial direction from the rim diameter reference position BL to the tire maximum width position W is within the range of 50% or more and 60% or less with respect to the tire cross-sectional height SH, the durability is lowered. While suppressing it, it is possible to more reliably secure riding comfort and low rolling resistance. That is, the maximum tire width position W is the portion most easily bent in the sidewall portion 8, but the height HW in the tire radial direction from the rim diameter reference position BL to the maximum tire width position W is the tire cross-sectional height SH. If it is less than 50%, the tire maximum width position W may be too close to the bead portion 30. The vicinity of the bead portion 30 has high rigidity due to the carcass main body portion 11 and the turn-up portion 12 being overlapped with each other, and is a portion that is difficult to bend. Therefore, if the tire maximum width position W is too close to the bead portion 30, it will be vertical. It may be difficult to effectively reduce the spring. In this case, since it is difficult to increase the contribution ratio of the sidewall portion 8 when the pneumatic tire 1 is deformed by the load, it is difficult to reduce the rolling resistance and the sidewall portion 8 is difficult to bend. There is a risk that it will be difficult to secure a comfortable ride when the vehicle is running. If the height HW in the tire radial direction from the rim diameter reference position BL to the tire maximum width position W exceeds 60% of the tire cross-sectional height SH, the tire maximum width position W may be too close to the tread portion 2. There is. In this case, the tire structure may be strained and the durability may be lowered.

On the other hand, when the height HW in the tire radial direction from the rim diameter reference position BL to the tire maximum width position W is within the range of 50% or more and 60% or less with respect to the tire cross-sectional height SH, the tire maximum. It is possible to prevent the large position W from getting too close to the bead portion 30 and the tread portion 2. As a result, the vertical spring of the pneumatic tire 1 can be more reliably reduced while suppressing the decrease in durability. As a result, it is possible to suppress the decrease in durability and more reliably reduce the rolling resistance while suppressing the deterioration of riding comfort.

Further, in the sidewall portion 8, since the thickness Gw of the side rubber 9 at the tire maximum width position W is within the range of 1 mm or more and 4 mm or less, the vertical spring can be made an appropriate size. That is, when the thickness Gw of the side rubber 9 at the maximum tire width position W is less than 1 mm, the thickness Gw of the side rubber 9 is too thin, so that the rigidity of the sidewall portion 8 becomes too low and the vertical spring may become too low. There is. In this case, the sidewall portion 8 may bend too much when a load is applied, and the sidewall portion 8 may bend excessively when the vehicle is running, which may make it difficult to reduce the rolling resistance. Further, when the thickness Gw of the side rubber 9 at the maximum tire width position W exceeds 4 mm, the thickness Gw of the side rubber 9 is too thick, so that the rigidity of the sidewall portion 8 becomes too high and the vertical spring is effectively reduced. May be difficult. In this case, since the sidewall portion 8 is less likely to bend, it may be difficult to secure a comfortable ride when the vehicle is traveling.

On the other hand, when the thickness Gw of the side rubber 9 at the maximum tire width position W is within the range of 1 mm or more and 4 mm or less, the rigidity of the sidewall portion 8 can be appropriately increased, and the vertical spring can be formed. It can be made into an appropriate size. As a result, rolling resistance can be reduced while more reliably suppressing deterioration of riding comfort.

Further, in the tread rubber 4, since the thickness Gc at the center position and the thickness Gs at the shoulder position are within the range of 2% or more and 10% or less of the tire cross-sectional height SH, respectively, the rigidity of the tread portion 2 is appropriately adjusted. The size can be adjusted to an appropriate size, and the deformation of the tread portion 2 and the reaction force from the tread portion 2 when the ground contact surface 3 touches the ground can be made an appropriate size. That is, when the thickness Gc at the center position of the tread rubber 4 and the thickness Gs at the shoulder position are less than 2% of the tire cross-sectional height SH, the thickness of the tread rubber 4 is too thin, so that the tread portion 2 There is a risk that the rigidity will be too low. In this case, the deformation of the tread portion 2 becomes too large when the ground contact surface 3 touches the ground, and the rolling resistance tends to increase as the tread portion 2 deforms significantly, so that it may be difficult to reduce the rolling resistance. is there. If the thickness Gc at the center position of the tread rubber 4 or the thickness Gs at the shoulder position exceeds 10% of the tire cross-sectional height SH, the thickness of the tread rubber 4 is too thick and the rigidity of the tread portion 2 is increased. May be too high. In this case, the reaction force from the tread portion 2 when the ground contact surface 3 touches the ground becomes large, and it becomes difficult to effectively reduce the vertical spring, so that it may be difficult to secure the riding comfort when the vehicle is running. is there.

On the other hand, when the thickness Gc at the center position of the tread rubber 4 and the thickness Gs at the shoulder position are within the range of 2% or more and 10% or less of the tire cross-sectional height SH, the thickness of the tread rubber 4 is adjusted. The thickness can be adjusted to an appropriate level, and the rigidity of the tread portion 2 can be set to an appropriate size. As a result, the deformation of the tread portion 2 and the reaction force from the tread portion 2 when the ground contact surface 3 touches the ground can be made an appropriate magnitude. As a result, rolling resistance can be reduced while more reliably suppressing deterioration of riding comfort.

Further, in the tread rubber 4, since the thickness Gc at the center position and the thickness Gs at the shoulder position satisfy the relationship of Gc ≧ Gs, the ground contact length near the shoulder portion 5 becomes the tire equator when the ground contact surface 3 touches the ground. It is possible to prevent the tire from becoming longer than the ground contact length near the surface CL. As a result, it is possible to make the ground pressure uniform when the ground surface 3 is grounded, and it is possible to suppress an increase in rolling resistance due to the non-uniform ground pressure. As a result, the rolling resistance can be reduced more reliably.

[Modification example]
In the pneumatic tire 1 according to the above-described embodiment, the bead wire 33 of the bead core 31 has a laminated structure of 3 + 4 + 3 + 2 + 1, but the bead wire 33 may be laminated with a structure other than this. FIG. 5 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory view when the bead wires 33 are laminated in six layers. As shown in FIG. 5, for example, the bead wire 33 of the bead core 31 has a layer including four rows of orbital portions and a layer including five rows of orbital portions and four rows of orbits in order from the inside to the outside in the tire radial direction. The structure may be such that a total of 6 layers, a layer including a portion, a layer including a three-row orbital portion, a layer including a two-row orbital portion, and a layer including a one-row orbital portion, are laminated. That is, the laminated structure of the bead wire 33 may be a 4 + 5 + 4 + 3 + 2 + 1 structure. In this way, even when the bead wires 33 are laminated in six layers, the outer shape 34 of the bead core 31 in the tire meridional cross section is a pentagon in which the apex 35 is located on the outer side in the tire radial direction and the base 36 is located on the inner side in the tire radial direction. It is preferably formed in the shape of a wedge on the outer diameter side.

FIG. 6 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory view of a modified example in which the bead wires 33 are laminated in five layers. Further, the bead wire 33 of the bead core 31 may have a 5 + 4 + 3 + 2 + 1 structure of bale stacking as shown in FIG. 6A even when laminated in 5 layers, and as shown in FIG. 6B, the bale may be formed. It may have a stacking 4 + 4 + 3 + 2 + 1 structure, and as shown in FIG. 6C, the innermost layer in the tire radial direction and the layer adjacent to the innermost layer in the tire radial direction on the outer side in the tire radial direction are formed. It may have a 4 + 4 + 3 + 2 + 1 structure in which the tires are stacked in series instead of being stacked in bales. That is, in the laminated structure shown in FIG. 6C, the innermost layer in the tire radial direction and the layer adjacent to the innermost layer in the tire radial direction on the outer side in the tire radial direction are perpendicular to the tire width direction. It is laminated.

Since at least a part of each of the structures shown in FIG. 6 is laminated in a bale-like manner, the bead wires 33 are arranged more densely than the bead wires 33 having a structure in which the whole is laminated in series. The filling rate can be increased. As a result, the mass of the pneumatic tire 1 can be reduced and these performances can be exhibited in a well-balanced manner while maintaining the running performance while satisfactorily ensuring the rigidity and pressure resistance performance of the bead portion 30.

Focusing on the filling rate of the bead wires 33, it is preferable that all the bead wires 33 are stacked in a bale shape as shown in FIGS. 6 (a) and 6 (b). Further, regarding the shape of the bead core 31, in order to improve the stability of the shape of the entire bead core 31, it is preferable that the shape of the entire bead core 31 is line-symmetrical with respect to the center of the bead core 31 in the tire width direction. From this point of view, the shapes shown in FIGS. 6 (a) and 6 (c) are preferable.

FIG. 7 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory view of a modified example in which the bead wires 33 are laminated in six layers. Further, when the bead wire 33 of the bead core 31 is laminated in 6 layers, as shown in FIG. 7A, the bead wire 33 has a 3 + 4 + 4 + 3 + 2 + 1 structure of bale stacking, and two layers including four rows of peripheral portions are laminated. The structure may be shifted in the tire width direction, and as shown in FIG. 7B, the second layer from the inner side in the tire radial direction and the layer adjacent to the inner side in the tire radial direction are stacked in a bale. Instead, the structure may be 3 + 4 + 4 + 3 + 2 + 1 stacked in series. Since the laminated structure of the bead wire 33 included in the bead core 31 can be laminated in various structures as described above, the laminated structure is appropriately selected in consideration of the structure of the entire pneumatic tire 1 and the characteristics to be emphasized. It is preferable to do so.

Further, in the above-described embodiment, the inner liner 16 is made of a rubber composition containing butyl rubber as a main component, but the inner liner 16 may be made of a material other than this. The inner liner 16 may be composed of, for example, a thermoplastic resin, a thermoplastic elastomer composition in which an elastomer component is blended in the thermoplastic resin, or the like.

Examples of the thermoplastic resin include copolymer resins [for example, nylon 6 (N6), nylon 66 (N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12), nylon 610 (N610), nylon. 612 (N612), nylon 6/66 copolymer (N6 / 66), nylon 6/66/610 copolymer (N6 / 66/610), nylon MXD6, nylon 6T, nylon 9T, nylon 6 / 6T copolymer Combined, nylon 66 / PP copolymer, nylon 66 / PPS copolymer], polyester resin [for example, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), polybutylene terephthalate / tetramethylene Glycol copolymer, PET / PEI copolymer, polyallylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, polyoxyalkylenediimide diic acid / aromatic polyester such as polybutylene terephthalate copolymer], polynitrile System resins [for example, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / styrene copolymer, methacrylonitrile / styrene / butadiene copolymer], poly (meth) Acrylic resin [for example, polymethyl methacrylate (PMMA), ethyl polymethacrylate, ethylene ethyl acrylate copolymer (EEA), ethylene acrylate copolymer (EAA), ethylene methyl acrylate resin (EMA)], polyvinyl resin [For example, vinyl acetate (EVA), polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride. / Methyl acrylate copolymer], cellulose-based resin [for example, cellulose acetate, cellulose acetate butyrate], fluorine-based resin [for example, polyvinylidene fluoride (PVDF), vinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluororo Ethylene / ethylene copolymer (ETFE)], imide resin [for example, aromatic polyimide (PI)] and the like can be adopted.

Elastomers include, for example, diene rubbers and their hydrogenated products [eg, NR, IR, epoxidized natural rubber, SBR, BR (high cis BR and low cis BR), NBR, hydride NBR, hydride SBR], olefins. System rubbers [for example, ethylene propylene rubber (EPDM, EPM), maleic acid-modified ethylene propylene rubber (M-EPM)], butyl rubber (IIR), isobutylene and aromatic vinyl or diene monomer copolymers, acrylic rubber (ACM), Ionomer, halogen-containing rubber [for example, Br-IIR, Cl-IIR, bromide of isobutylene paramethylstyrene copolymer (Br-IPMS), chloroprene rubber (CR), hydrin rubber (CHC, CHR), chlorosulfonated polyethylene (CSM) ), Chlorinated polyethylene (CM), maleic acid-modified chlorinated polyethylene (M-CM)], silicone rubber [for example, methyl vinyl silicone rubber, dimethyl silicone rubber, methylphenyl vinyl silicone rubber], sulfur-containing rubber [for example, polysulfide rubber], Fluorine rubber [for example, vinylidene fluoride-based rubber, fluorovinyl ether-based rubber, tetrafluoroethylene-propylene-based rubber, fluorine-containing silicon-based rubber, fluorine-containing phosphazene-based rubber], thermoplastic elastomers [for example, styrene-based elastomer, olefin-based elastomer, Polyester-based elastomer, urethane-based elastomer, polyamide-based elastomer] and the like can be adopted.

When the inner liner 16 is made of a thermoplastic resin or a thermoplastic elastomer composition, the inner liner 16 is thinner than the case where the inner liner 16 is made of a rubber composition containing butyl rubber as a main component. Can be transformed into. As a result, the tire weight can be significantly reduced.

Further, in the above-described embodiment, the tie rubber 40 is disposed between the sidewall portions 8 on both sides in the tire width direction via the tread portion 2, but the tie rubber 40 is arranged on both sides in the tire width direction. It does not have to be continuously arranged between the portions 8. The tie rubber 40 may be divided into a tie rubber 40 disposed on one sidewall portion 8 side in the tire width direction and a tie rubber 40 disposed on the other sidewall portion 8 side, for example, a belt. The tie rubber 40 may be divided at a position inside the layer 14 in the tire radial direction. The tie rubber 40 may be disposed at least between the carcass layer 10 located at the sidewall portion 8 and the inner liner 16, regardless of whether the tie rubber 40 is continuous or divided between the sidewall portions 8. Instead, the tie rubber terminal portion 41 may be located outside the turn-up edge portion 12a of the turn-up portion 12 in the tire radial direction.

[Example]
8A and 8B are charts showing the results of the performance evaluation test of the pneumatic tire. Hereinafter, with respect to the above-mentioned pneumatic tire 1, the performance of the conventional pneumatic tire, the pneumatic tire 1 according to the present invention, and the pneumatic tire of the comparative example compared with the pneumatic tire 1 according to the present invention. The evaluation test will be described. Performance evaluation tests were conducted on rolling resistance and riding comfort.

The performance evaluation test was carried out by assembling a pneumatic tire 1 having a tire nominal size of 205 / 60R16 92V specified by JATTA on a JATTA standard rim wheel having a rim size of 16 × 6.0J.

The evaluation method for each test item is to adjust the air pressure to 180 kPa and use an indoor drum tester (drum diameter: 1707 mm) for rolling resistance, and to comply with ISO28580, load 4.8 kN, speed 80 km / h. The rolling resistance coefficient in was calculated. The result was evaluated by expressing it as an exponent in which the reciprocal of the rolling resistance coefficient of the conventional example described later is 100. The larger this index, the lower the rolling resistance, indicating that the performance of rolling resistance is excellent.

Regarding riding comfort, when a test tire with an air pressure adjusted to 250 kPa was mounted on a front-wheel drive test vehicle with a displacement of 1500 cc, a load equivalent to two passengers was applied and the test vehicle ran on the test course. Riding comfort was compared by sensory evaluation of test drivers. The ride comfort was evaluated by an index of 100 in the conventional example described later in the sensory evaluation of the test driver. The larger this index is, the better the riding comfort is, indicating that the performance regarding the riding comfort is excellent.

The performance evaluation test compares the conventional pneumatic tire, which is an example of the conventional pneumatic tire, the pneumatic tires 1 according to the present invention, Examples 1 to 11, and the pneumatic tire 1 according to the present invention. 16 types of pneumatic tires with Comparative Examples 1 to 4 which are pneumatic tires were used. Of these, the pneumatic tire of the conventional example has a bead filler, and the tie rubber terminal portion 41 is located inside the turn-up edge portion 12a in the tire radial direction. Further, in Comparative Example 1, although the bead filler is not provided, the tie rubber terminal portion 41 is located inside the turn-up edge portion 12a in the tire radial direction. Further, although Comparative Examples 2 to 4 do not have a bead filler and the tie rubber terminal portion 41 is located outside the turn-up edge portion 12a in the tire radial direction, Comparative Example 2 is based on the rim diameter. The height HQ from the position BL to the tie rubber terminal portion 41 is out of the range of 11% or more and 60% or less of the tire cross-sectional height SH. Further, in Comparative Example 3, the height HR from the rim diameter reference position BL to the turn-up edge portion 12a is out of the range of 10% or more and 50% or less of the tire cross-sectional height SH. Further, in Comparative Example 4, the distance RQ between the turn-up edge portion 12a and the tie rubber terminal portion 41 is out of the range of 1% or more and 30% or less of the tire cross-sectional height SH.

On the other hand, Examples 1 to 11, which are examples of the pneumatic tire 1 according to the present invention, do not have any bead filler, and the tie rubber terminal portion 41 is outside the tire radial direction with respect to the turn-up edge portion 12a. The height HR from the rim diameter reference position BL to the turn-up edge portion 12a is within the range of 10% or more and 50% or less of the tire cross-sectional height SH, and from the rim diameter reference position BL to the tie rubber terminal portion 41. The height HQ is within the range of 11% or more and 60% or less of the tire cross-sectional height SH, and the distance RQ between the turn-up edge portion 12a and the tie rubber terminal portion 41 is within the range of 1% or more and 30% or less of the tire cross-sectional height SH. It has become. Further, the pneumatic tire 1 according to Examples 1 to 11 has the size of the tread radius TR, the contact width TW / the maximum tire width SW, the maximum tire width position W height HW / the tire cross-sectional height SH, and the maximum tire width. Side rubber 9 thickness Gw at position W, tread rubber 4 thickness Gc at center position / tire cross-sectional height SH, tread rubber 4 thickness Gs at shoulder position / tire cross-sectional height SH, tread rubber 4 The relationship between the thickness Gc at the center position and the thickness Gs at the shoulder position is different.

As a result of performing a performance evaluation test using these pneumatic tires 1, as shown in FIGS. 8A and 8B, the pneumatic tires 1 according to Examples 1 to 11 are based on the conventional examples and Comparative Examples 1 to 4. Therefore, it was found that both the rolling resistance and the riding comfort can be improved. That is, the pneumatic tire 1 according to the first to eleventh embodiments can reduce the rolling resistance while suppressing the deterioration of the riding comfort.

1 Pneumatic tire 2 Tread part 3 Ground surface 4 Tread rubber 4a Cap rubber 4b Base rubber 5 Shoulder part 8 Side wall part 9 Side rubber 10 Carcus layer 11 Carcus body part 12 Turn-up part 12a Turn-up edge part 14 Belt layer 16 Inner liner 18 Tire inner surface 20 Land part 25 Circumferential groove 30 Bead part 31 Bead core 32 Outer end 33 Bead wire 34 Outer shape 35 Top 36 Bottom 40 Tread rubber 41 Tread rubber end

Claims (6)

A tread portion that extends in the tire circumferential direction and is formed in an annular shape and has tread rubber,
A pair of sidewall portions arranged on both sides of the tread portion,
A pair of bead portions arranged inside each of the pair of sidewall portions in the tire radial direction,
The bead core arranged in the bead portion and
A carcass layer spanning between the pair of bead portions,
An inner liner arranged on the inner surface of the tire along the carcass layer,
With
The carcass layer is formed continuously from the carcass main body portion that is bridged between the pair of bead portions and the carcass main body portion, and is folded back from the inside in the tire width direction to the outside in the tire width direction along the peripheral edge of the bead core. It has a turn-up portion extending from the position of the outer end portion of the bead core in the tire radial direction toward the sidewall portion side while contacting the carcass main body portion.
A tie rubber is disposed between the carcass layer located on the sidewall portion and the inner liner.
The height of the carcass layer in the tire radial direction from the reference position on the inner side of the tire cross-sectional height in the tire radial direction to the turn-up edge portion which is the outer end of the turn-up portion in the tire radial direction is the tire cross section. Within the range of 10% or more and 50% or less of the height,
The tie rubber terminal portion, which is the inner end portion in the tire radial direction, is located outside the turn-up edge portion in the tire radial direction, and the height of the tie rubber terminal portion in the tire radial direction from the reference position. However, it is within the range of 11% or more and 60% or less of the tire cross-sectional height.
A pneumatic tire characterized in that the distance between the turn-up edge portion and the tie rubber terminal portion is within a range of 1% or more and 30% or less of the cross-sectional height of the tire. The pneumatic tire according to claim 1, wherein the tread radius of the tread portion in the tire meridional cross section is within the range of 600 mm or more and 1700 mm or less. The pneumatic tire according to claim 1 or 2, wherein the ground contact width is within the range of 60% or more and 90% or less of the maximum tire width. The one according to any one of claims 1 to 3, wherein the height in the tire radial direction from the reference position to the maximum tire width position is within the range of 50% or more and 60% or less with respect to the tire cross-sectional height. Pneumatic tires. The aspect according to any one of claims 1 to 4, wherein the thickness of the side rubber of the carcass layer located outside in the tire width direction at the tire maximum width position is in the range of 1 mm or more and 4 mm or less. Pneumatic tires. In the tread rubber, the thickness Gc at the center position and the thickness Gs at the shoulder position satisfy the relationship of Gc ≧ Gs, and the thickness Gc at the center position and the thickness Gs at the shoulder position are The pneumatic tire according to any one of claims 1 to 5, each of which is within the range of 2% or more and 10% or less of the cross-sectional height of the tire.

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