JP2019209904A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire which can improve steering performance while suppressing braking performance deterioration and rolling resistance deterioration.SOLUTION: A pneumatic tire comprises: a pair of bead parts 30; a carcass layer 10 which is bridged between the pair of bead parts 30; and an inner liner 16 which is provided on a tire inner surface 18 along the carcass layer 10. The carcass layer 10 has a carcass body part 11 and a turn-up part 12, and a tie rubber 40 is provided between the carcass layer 10 and the inner liner 16. The tie rubber 40 overlaps the turn-up part 12 in such a manner that a tie rubber terminal part 41 is positioned on a tire radial direction inner side with respect to a turn-up edge part 12a of the turn-up part 12. An overlap amount H1 of the tie rubber 40 with respect to the turn-up part 12 falls within a range of 20% or more and 60% or less of a turn-up width Ht which is an interval between an outer end part 32 of a bead core 31 and the turn-up edge part 12a.SELECTED DRAWING: Figure 1

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 the fuel efficiency when the vehicle is running. For this reason, some conventional pneumatic tires are designed to reduce rolling resistance or reduce 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 set within the predetermined range, and the bead portion is formed from the tread ground 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 reinforcement layer is disposed on the outer side in the tire width direction of the carcass at the tire maximum width position, and is embedded in the width of the carcass ply reinforcement layer and the carcass ply reinforcement layer. It defines the angle of the reinforcing element. Moreover, in the pneumatic tire described in Patent Document 3, the height of the bead filler is defined. In patent documents 1-3, reduction of rolling resistance is aimed at by performing these regulations.

  Moreover, weight reduction of the bead part is proposed as one method for realizing weight reduction. As a conventional pneumatic tire for reducing the weight of the bead portion, techniques described in Patent Documents 4 to 6 are known. In patent documents 4-6, weight saving of a pneumatic tire is aimed at by omitting a bead filler.

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

  Here, the pneumatic tire is required to have various performances in addition to reduction in rolling resistance and weight reduction. For example, braking performance during braking of the vehicle and steering performance during traveling of the vehicle are required. The braking performance can be improved by using a tread rubber having a high tan δ. However, if the tan δ of the tread rubber is increased, the rolling resistance is likely to deteriorate. One technique for achieving both braking performance and low rolling resistance is to lower the tan δ of the tread rubber, to make the profile of the tread portion relatively flat, and to reduce the thickness of the side rubber. Thus, by reducing the tan δ of the tread rubber, it is possible to suppress the deterioration of the rolling resistance, and by making the profile of the tread portion flat, the contact area can be increased, so that the braking performance is improved. be able to. Further, by reducing the thickness of the side rubber, the rigidity of the tire side portion is lowered, so that it is easy to bend when a load is applied, the contact area can be increased, and the braking performance can be improved.

  However, when the thickness of the side rubber is reduced, there is a possibility that the difference in rigidity between the position of the tire side portion where the turn-up portion of the carcass layer is disposed and the other position becomes too large. That is, when the bead filler is omitted, the rigidity in the vicinity of the bead portion is important for the carcass layer, but at the position where the turn-up portion is disposed, the carcass ply constituting the carcass layer is divided into two pieces. On the other hand, on the outer side in the tire radial direction at the position where the turn-up portion is disposed, there is one carcass ply constituting the carcass layer. For this reason, the rigidity in the vicinity of the turn-up portion is significantly lower than the rigidity at the position of the turn-up portion on the outer side in the tire radial direction compared to the rigidity at the position where the turn-up portion is disposed in the tire radial direction. There is a fear.

  In this case, when a load is applied to the tire side part, the position of the turn-up part of the relatively low rigidity of the turn-up part in the tire radial direction is first bent by the load, and then the turn-up part having a relatively high rigidity is provided. The disposed position is bent. At that time, since the rigidity is greatly different between the position where the turn-up portion is disposed and the position outside the tire radial direction of the turn-up portion, the load when the position where the turn-up portion is disposed is bent. The way of bending with respect to the load is significantly smaller than the way of bending of the turn-up portion at the outer side in the tire radial direction. For this reason, how to bend with respect to a load load largely changes before and after the position where the turn-up portion is disposed begins to bend, and there is a concern that the steering performance may deteriorate due to this. That is, there is a possibility that the steering performance including the ride comfort may be deteriorated due to a sudden change in the bending method with respect to the load. As described above, it has been very difficult to achieve both braking performance and low rolling resistance and to improve the handling performance.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can improve steering performance, suppressing the fall of braking performance and the deterioration of rolling resistance.

  In order to solve the above-described problems and achieve the object, a pneumatic tire according to the present invention is formed in an annular shape extending in the tire circumferential direction and having tread rubber, and on both sides of the tread portion. A pair of sidewall portions, a pair of bead portions disposed inside each of the pair of sidewall portions in the tire radial direction, a bead core disposed in the bead portion, and a pair of the beads A carcass layer spanned between the parts, and an inner liner disposed on the inner surface of the tire along the carcass layer, the carcass layer spanning between the pair of bead parts, It is formed continuously from the carcass main body and is folded back from the inner side in the tire width direction to the outer side in the tire width direction along the periphery of the bead core so as to be disposed in the tire radial direction of the bead core. A turn-up portion extending toward the sidewall portion while contacting the carcass main body portion from the position of the outer end portion, and the carcass layer located on the sidewall portion and the inner liner A tie rubber is disposed between the tie rubbers, and the tie rubber terminal portion, which is an end portion on the inner side in the tire radial direction, has a tire radial direction than the turn-up edge portion, which is an end portion on the outer side in the tire radial direction of the turn-up portion. By being located on the inner side, it overlaps with the turn-up part in the tire radial direction, and the overlap amount H1 of the tie rubber with respect to the turn-up part is equal to the outer end part of the bead core and the turn-up edge. The turn-up width Ht, which is the distance from the portion, is in the range of 20% to 60%.

  In the pneumatic tire, the turn-up width Ht is a turn-up portion inner reference line that is a normal line of the carcass layer that passes through the outer end portion of the bead core, and the turn-up portion passes through the turn-up edge portion. The distance between the turn-up portion inner reference line and the turn-up portion outer reference line when a line parallel to the inner reference line is used as the turn-up portion outer reference line, and the overlap amount H1 is the tie rubber terminal. It is preferable that the distance between the tie rubber terminal portion reference line and the turnup portion outer reference line when a line passing through the portion and parallel to the turnup portion inner reference line is used as the tie rubber terminal portion reference line.

  In the pneumatic tire, a thickness Gt of the tie rubber at the position of the tie rubber terminal portion and a thickness Gi of the inner liner at a position adjacent to the tie rubber terminal portion are in a relationship of Gt ≦ Gi. Preferably there is.

  In the pneumatic tire, the thickness Gi of the inner liner is preferably a thickness of the inner liner on a normal line of the carcass layer passing through the tie rubber terminal portion.

  In the pneumatic tire, the tread radius of the tread portion in the tire meridional section is in a range of 600 mm to 1700 mm, and a contact width is in a range of 60% to 90% of the maximum tire width. Is preferred.

  In the pneumatic tire, the height in the tire radial direction from the reference position inside the tire radial direction to the tire maximum width position of the tire cross-sectional height is in a range of 50% to 60% with respect to the tire cross-sectional height. It is preferable to be within.

  In the pneumatic tire, the sidewall portion preferably has a thickness of a side rubber located on the outer side in the tire width direction of the carcass layer at the tire maximum width position in a range of 1 mm to 4 mm.

  In the pneumatic tire, the tread rubber has a thickness Gc at the center position and a thickness Gs at the shoulder position satisfying a relationship of Gc ≧ Gs, and the thickness Gc at the center position and the shoulder The thickness Gs at the position is preferably in the range of 2% to 10% of the tire cross-section height.

  In the pneumatic tire, the turn-up portion has a height in the tire radial direction from a reference position inside the tire radial direction of the tire cross-section height to the turn-up edge portion of 10% or more of the tire cross-section height. It is preferably within the range of 40% or less.

  The pneumatic tire according to the present invention has an effect that the steering performance can be improved while suppressing the deterioration of the braking performance and the deterioration of the rolling resistance.

FIG. 1 is a meridional cross-sectional view showing a main part of a pneumatic tire according to an embodiment. FIG. 2 is a detailed view of a sidewall portion and a 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 diagram when 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 diagram 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 diagram of a modified example in which bead wires are laminated in six layers. FIG. 8A is a chart showing the results of a performance evaluation test of a pneumatic tire. FIG. 8B is a chart showing the results of a performance evaluation test of a pneumatic tire. FIG. 8C is a chart showing the results of a performance evaluation test of a pneumatic tire.

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

[Embodiment]
In the following description, the tire radial direction refers to a direction orthogonal to a tire rotation axis (not shown) that is the rotation axis of the pneumatic tire 1, and the tire radial direction inner side refers to the side toward the tire rotation axis in the tire radial direction. The outer side in the tire radial direction refers to the side away from the tire rotation axis in the tire radial direction. Further, the tire circumferential direction refers to a circumferential direction with the tire rotation axis as the central axis. Further, the tire width direction means a direction parallel to the tire rotation axis, the inner side in the tire width direction means the side toward the tire equator plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction means the tire width direction. Is 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. The tire equatorial plane CL is a tire that is the center position of the pneumatic tire 1 in the tire width direction. The center line in the width direction matches the position in the tire width direction. The tire width is the width in the tire width direction between the outermost portions 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 equator line is a line along the tire circumferential direction of the pneumatic tire 1 on the tire equator plane CL. Further, in the following description, the tire meridian section refers to a section when the tire is cut along a plane including the tire rotation axis.

  FIG. 1 is a meridional cross-sectional view showing a main part of a pneumatic tire 1 according to an embodiment. The pneumatic tire 1 according to the present embodiment includes a tread portion 2 that extends in the tire circumferential direction and is formed in an annular shape at the outermost portion in the tire radial direction when viewed in the tire meridian 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, a portion that comes into contact with the road surface when the vehicle (not shown) on which the pneumatic tire 1 is mounted is formed as the ground surface 3, and the ground surface 3 is the surface of the pneumatic tire 1. Part of the contour. A plurality of circumferential grooves 25 extending in the tire circumferential direction and lug grooves (not shown) extending in the tire width direction are formed in the tread portion 2 in the tire circumferential direction, and these circumferential grooves 25 and lug grooves are formed. Thus, 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 wave shape or a zigzag shape that extends in the tire circumferential direction and swings in the tire width direction. The lug groove may also extend linearly in the tire width direction, tilt in the tire circumferential direction while extending in the tire width direction, or bend or bend 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 includes a cap rubber 4a that forms the ground contact surface 3, and a base rubber 4b that is located on the inner side in the tire radial direction of the cap rubber 4a. That is, the tread portion 2 is configured by laminating the cap rubber 4a and the base rubber 4b in the tire radial direction. These cap rubber 4a and base rubber 4b have a tan δ at 60 ° C. of 0.3 or less.

  Note that tan δ 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%, temperature 60 ° C. 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 disposed on the inner side of the shoulder portion 5 in the tire radial direction. That is, the pair of sidewall portions 8 are disposed on both sides of the tread portion 2 in the tire width direction. In other words, the sidewall portions 8 are disposed on two sides of the pneumatic tire 1 in the tire width direction. ing. The side wall portion 8 formed in this manner is a portion exposed to the outermost side in the tire width direction of the pneumatic tire 1 and has a side rubber 9 that is a rubber material.

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

  A belt layer 14 is provided on the inner side in the tire radial direction of the tread portion 2. The belt layer 14 is formed by laminating a pair of cross belts 141 and 142 and a belt cover 143. The pair of cross belts 141 and 142 are formed by rolling a plurality of belt cords made of steel or organic fiber materials such as polyester, rayon, nylon, etc. with a coating rubber, and an inclination angle of the belt cord with respect to the tire circumferential direction. Is within a predetermined range (for example, 20 ° or more and 55 ° or less). The pair of cross belts 141 and 142 have different belt angles. For this reason, the pair of cross belts 141 and 142 is configured as a so-called cross-ply structure in which the belt cords are stacked so that their inclination directions cross each other.

  The belt cover 143 is configured by coating a belt cover cord made of steel or an organic fiber material such as polyester, rayon, or nylon with a coat rubber, and a belt angle defined as an inclination angle of the belt cord with respect to the tire circumferential direction is a predetermined angle. (For example, 0 ° or more and 10 ° or less). In the present embodiment, the belt cover 143 is disposed so as to cover the entire pair of cross belts 141 and 142. The pair of belt covers 143 are, for example, strip materials formed by coating one or a plurality of belt cover cords with a coat rubber, and the strip materials are arranged in the tire circumferential direction with respect to the outer circumferential surfaces of the cross belts 141 and 142. It is configured to be wound in a spiral manner a plurality of times. Further, the belt cover 143 may have other configurations. The belt cover 143 may be disposed, for example, only near the ends in the tire width direction of the pair of cross belts 141, 142, or the belt cover 143 that covers the entire cross belts 141, 142, and the cross belts 141, 142 A belt cover 143 disposed only in the vicinity of the end portion in the tire width direction 142 may be laminated.

  A carcass layer 10 including a radial ply cord is continuously provided on the inner side in the tire radial direction of the belt layer 14 and on the tire equatorial plane CL side of the sidewall portion 8. For this reason, 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 multilayer structure formed by laminating a plurality of carcass plies, and a toroidal portion between a pair of bead portions 30 disposed on both sides in the tire width direction. A tire skeleton is constructed by laying in the shape of a tire.

  Specifically, the carcass layer 10 is disposed 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. The bead core 31 is wrapped around the bead core 31 along the bead core 31 so as to wrap the bead core 31. For this reason, the carcass layer 10 is folded back while being bent along the periphery of the bead core 31 at the bead portion 30 between the carcass main body portion 11 spanned between the pair of bead portions 30 and the outer end of the bead core 31 in the tire radial direction. The turnup portion 12 extends from the position of the portion 32 toward the side wall portion 8 while contacting the carcass main body portion 11. Among 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 disposed in the bead portion 30, along the periphery of the bead core 31 from the inner side in the tire width direction to the tire width direction. It is folded to the outside.

  Further, the belt layer 14 is arranged on the outer side in the tire radial direction of the portion located in the tread portion 2 in the carcass layer 10 spanned between the pair of bead portions 30 in this way. In addition, the carcass ply of the carcass layer 10 is formed by coating and rolling a plurality of carcass cords made of steel or organic fiber materials such as aramid, nylon, polyester, rayon, etc. with a coat rubber. The carcass cords constituting the carcass ply are arranged such 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 in the range of 80 ° or more and 90 ° or less, and a plurality of them are arranged in parallel. ing.

  A rim cushion rubber 17 constituting a contact surface of the bead portion 30 with respect to the rim flange is disposed on the inner side in the tire radial direction and the outer side in the tire width direction of the bead core 31 and the turnup portion 12 of the carcass layer 10 in the bead portion 30. Yes.

  An inner liner 16 is disposed along the carcass layer 10 on the inner side 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 disposed on the tire inner surface 18 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. Moreover, the inner liner 16 is comprised with the rubber composition which has butyl rubber as a main component. Examples of the rubber composition containing butyl rubber as a main component include butyl rubber (IIR) and butyl rubber. 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 disposed 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 prevents the carcass cord from biting into the inner liner 16 when the unvulcanized pneumatic tire 1 is inflated during tire manufacture. In the pneumatic tire 1 after manufacture, it contributes to air permeation prevention and steering stability on a dry road surface. The tie rubber 40 is disposed between at least the carcass layer 10 and the inner liner 16 located in the sidewall portion 8, 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 arrange | positions over between the parts 8. FIG.

  Further, in the pneumatic tire 1 according to the present embodiment, the tread radius TR of the tread portion 2 in the tire meridional section is in 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 The tire outer diameter is in the range of 100% to 140%. That is, the tread portion 2 is formed with a relatively flat profile as a reference for the ground plane 3. In this case, the tread radius TR is a radius ruler that determines the radius of the contact surface 3 of the tread portion 2 in the direction along the meridian cross section of the pneumatic tire 1 in a state in which the pneumatic tire 1 is assembled on a regular rim and filled with a regular internal pressure. It is the value measured by.

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

  Further, the tread portion 2 has a ground contact width TW in a range of 60% to 90% of the maximum tire width SW. The contact width TW here is an interval in the tire width direction between the contact ends T of the contact surface 3. The ground contact edge T is the contact when the pneumatic tire 1 is assembled to a regular rim and filled with a regular internal pressure, and is placed perpendicular to the flat plate in a stationary state and a load corresponding to a regular load is applied. The outermost ends in the tire width direction of the area in contact with the flat plate in the ground 3 are referred to and are continuous in the tire circumferential direction. The normal load here is “maximum load capacity” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO.

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

  Further, in the pneumatic tire 1 according to this embodiment, the height HW in the tire radial direction from the reference position inside the tire radial direction of the tire cross-sectional height SH to the tire maximum width position W is higher than the tire cross-sectional height SH. Therefore, it is within the range of 50% or more and 60% or less. The tire cross-section height SH referred to here is a distance in the tire radial direction between a portion of the tread portion 2 that is located on the outermost side in the tire radial direction and the rim diameter reference position BL. That is, the tire cross-section height SH corresponds to the tire outer diameter and the rim when the pneumatic tire 1 is assembled on a regular rim, filled with a regular internal pressure, and no load is applied to the pneumatic tire 1. One half of the difference from the diameter. Therefore, the reference position inside the tire radial direction of the tire cross-section height SH is the rim diameter reference position BL, and the tire from the reference position inside the tire radial direction of the tire cross-section height SH 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. The tire maximum width position W is a position in the tire radial direction at a position that becomes the tire maximum width SW.

  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% to 56% with respect to the tire cross-section height SH.

  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. Here, the thickness Gc at the center position and the thickness Gs at the shoulder position are the combined thicknesses 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 equator plane CL. That is, in the present embodiment, the thickness Gc of the tread rubber 4 at the center position is the normal direction of the ground contact surface 3 passing through the intersection of the ground contact surface 3 and the tire equator surface CL, and is on the ground contact surface 3 side of the belt cover 143. This is the distance between the surface and the grounding surface 3. The thickness Gs at the shoulder position is the thickness of the tread rubber 4 measured in the normal direction of the ground plane 3 passing through the intersection of the ground plane 3 and the ground end T. That is, in this embodiment, the thickness GS of the tread rubber 4 at the shoulder position is the surface on the grounding surface 3 side of the belt cover 143 in the normal direction of the grounding surface 3 passing through the intersection of the grounding surface 3 and the grounding end T. And the ground plane 3.

  When the circumferential groove 25 is disposed on the tire equatorial plane CL, the thickness Gc of the tread rubber 4 at the center position is the same as that of the ground plane 3 at the position closest to the tire equatorial plane CL on the ground plane 3. The thickness of the tread rubber 4 is measured in the line direction.

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

  FIG. 2 is a detailed view of the sidewall portion 8 and the bead portion 30 shown in FIG. In the sidewall portion 8, the side rubber 9 has a relatively small thickness. Specifically, the thickness Gw of the side rubber 9 located on the outer side in the tire width direction of the carcass layer 10 at the tire maximum width position W is 1 mm. It is in the range of 4 mm or less. Note that the thickness Gw of the side rubber 9 at the tire maximum 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 tire radial height TUH from the rim diameter reference position BL to the turn-up edge portion 12a that is an end portion of the turn-up portion 12 on the outer side in the tire radial direction. The cross-sectional height SH is in the range of 10% to 40%. That is, in the turn-up portion 12, the turn-up edge portion 12a is located on the inner side in the tire radial direction from the tire maximum width position W. Note that the height TUH of the turn-up portion 12 from the rim diameter reference position BL to the turn-up edge portion 12a in the tire radial direction is preferably in the range of 20% to 30%.

  FIG. 3 is a detailed view of the bead unit 30 shown in FIG. In the tie rubber 40 disposed between the carcass layer 10 and the inner liner 16, the position in the tire radial direction of the tie rubber terminal portion 41, which is the end portion on the inner side in the tire radial direction, is the turn-up edge portion 12a of the turn-up portion 12. And the outer end 32 of the bead core 31 in the tire radial direction. That is, the tie rubber terminal portion 41 is located on the inner side in the tire radial direction than the turn-up edge portion 12 a of the turn-up portion 12, and located on the outer side in the tire radial direction than the outer end portion 32 of the bead core 31. For this reason, the tie rubber 40 is disposed so as to overlap the turnup portion 12 in the tire radial direction.

  Specifically, the overlap amount H1 of the tie rubber 40 with respect to the turnup portion 12 is within a range of 20% or more and 60% or less of the turnup width Ht that is the distance between the outer end portion 32 of the bead core 31 and the turnup edge portion 12a. It has become. Among these, the turn-up width Ht is defined as a turn-up portion inner reference line Lui that is a normal line of the carcass layer 10 passing through the outer end portion 32 of the bead core 31, and is parallel to the turn-up portion inner reference line Lui through the turn-up edge portion 12a. This is the distance between the turn-up portion inner reference line Lui and the turn-up portion outer reference line Luo when the straight line is the turn-up portion outer reference line Luo. The turn-up portion inner reference line Lui is specifically a normal line of the carcass main body portion 11 that passes through the outer end portion 32 of the bead core 31. Further, the overlap amount H1 is the tie rubber terminal reference line Lt and the turnup part outer reference line when a line passing through the tie rubber terminal part 41 and parallel to the turnup part inner reference line Lui is the tie rubber terminal reference line Lt. It is the distance from Luo.

  The overlap amount H1 with respect to the turn-up width Ht is preferably in the range of 30% to 50%.

  Further, the tie rubber 40 and the inner liner 16 are such that the thickness Gt of the tie rubber 40 at the position of the tie rubber terminal portion 41 and the thickness Gi of the inner liner 16 at a position adjacent to the tie rubber terminal portion 41 are Gt ≦ Gi. It has become a relationship. The thickness Gt of the tie rubber 40 at the position of the tie rubber terminal portion 41 is the thickness of the tie rubber 40 on the normal Lc of the carcass layer 10 passing through the tie rubber terminal portion 41, and the thickness Gi of the inner liner 16 is The thickness of the inner liner 16 on the normal line Lc of the carcass layer 10 passing through the tie rubber terminal portion 41 is set. That is, in the tie rubber 40, the thickness Gt at the position of the tie rubber terminal portion 41 on the normal line Lc of the carcass layer 10 passing through the tie rubber terminal portion 41 is equal to or less than the thickness Gi of the inner liner 16. Yes. In addition, the normal line Lc of the carcass layer 10 passing through the tie rubber terminal portion 41 is specifically the normal line of the carcass main body portion 11 passing through the tie rubber terminal portion 41. In addition, the thickness Gt of the tie rubber 40 at the position of the tie rubber terminal portion 41 is in a range of 50% or less and 90% or less of the thickness Gi of the inner liner 16 on the normal line Lc of the carcass layer 10 passing through the tie rubber terminal portion 41. Is preferably within.

  In the present embodiment, the inclination angle of the carcass main body portion 11 with respect to the tire radial direction at a position adjacent to the tie rubber terminal portion 41 and the tire diameter of the carcass main body portion 11 at a position adjacent to the outer end portion 32 of the bead core 31. Since the inclination angle with respect to the direction is substantially the same angle, the normal line Lc of the carcass layer 10 passing through the tie rubber terminal part 41 and the tie rubber terminal part reference line Lt parallel to the turnup part inner reference line Lui are: Almost matches.

  The bead core 31 disposed in the bead portion 30 includes at least one bead wire 33 wound in the tire circumferential direction, and at least one row in which a plurality of circumferential portions of the bead wire 33 are arranged in the tire width direction in the tire meridional section. And a plurality of layers overlapping in the tire radial direction. 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 circumferential portions of the bead wire 33 form rows and layers in the tire meridional section. A so-called layer winding structure in which a plurality of bead wires 33 are wound together may be used. In the present embodiment, a layer including three circumferential portions in order from the innermost side in the tire radial direction, a layer including four circumferential portions, a layer including three circumferential portions, a layer including two circumferential portions, and one row A total of five layers including the surrounding portion are stacked. In the following description, such a laminated structure of the bead wires 33 is referred to as “3 + 4 + 3 + 2 + 1 structure”. Similarly, in the following description, the laminated structure of the bead wires 33 is expressed in a similar format in which the number of rows included in each layer is connected by “+” in order from the innermost layer in the tire radial direction. Furthermore, in this embodiment, in the bead core 31, the bead wires 33 are stacked in a stacked manner. In this case, “stacking” is a stacking method in which the centers of the three surrounding portions that are in contact with each other form a substantially equilateral triangle, and may be referred to as a hexagonal packing arrangement. It is.

  FIG. 4 is a detailed view of the bead core 31 shown in FIG. In the bead core 31, when a polygon formed by a common tangent of a plurality of circumferential portions of the bead wire 33 in the tire meridional section is an outer shape 34 of the bead core 31, the outer shape 34 has a single vertex 35 on the outer side in the tire radial direction. And a base 36 so as to face the apex 35 on the inner side in the tire radial direction. That is, in this embodiment, the bead core 31 has a pentagonal outer shape 34 because the bead wire 33 has a 3 + 4 + 3 + 2 + 1 structure. In addition, the bead core 31 has an acute inner 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 decreases from the maximum width portion toward the outer side 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 “outer diameter side wedge shape”. Further, since the apex 35 of the outer shape 34 is located on the outermost side of the bead core 31 in the tire radial direction, the apex 35 of the outer 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 periphery of the bead core 31. That is, since the bead core 31 has a substantially pentagonal shape in the tire meridional section, the carcass layer 10 extending along the periphery of the bead core 31 is also bent into a substantially pentagonal shape. Furthermore, a portion of the turn-up portion 12 of the carcass layer 10 that is outside the tire radial direction outer end of the bead core 31 is in contact with the carcass main body portion 11 of the carcass layer 10 while contacting the carcass main body portion 11 of the carcass layer 10. 11 extends toward the side wall 8 side. Therefore, a closed region surrounding the bead core 31 is formed in the bead portion 30 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 body portion 11 and the turn-up portion 12 of the carcass layer 10, substantially only the bead core 31 exists. For this reason, in the pneumatic tire 1 according to the present embodiment, a bead filler or a similar tire constituent member used in a conventional pneumatic tire (a carcass of the carcass layer 10 disposed outside 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 and increases the rigidity from the bead portion 30 to the sidewall portion 8 is not disposed. That is, in the pneumatic tire 1, the insulation rubber covering the bead wire 33 and the rubber filling the slight gap formed between the bead core 31 and the carcass layer 10 exist in the closed region. No bead filler having a large volume such as a pneumatic tire is used. 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 section is the rubber occupation rate of the closed region. Then, the rubber occupation rate is in the range of 0.1% to 15%.

  When the pneumatic tire 1 according to this embodiment is mounted on a vehicle, the rim wheel is fitted to the rim wheel by fitting the rim wheel to the bead portion 30, and the inside is filled with air. Attach to the vehicle in a fret state. When the vehicle equipped with the pneumatic tire 1 travels, the pneumatic tire 1 rotates while the ground contact surface 3 located below the ground contact surface 3 is in contact with the road surface. The vehicle travels by transmitting a driving force or a braking force to the road surface or generating a turning force by the frictional force between the ground contact surface 3 and the road surface.

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

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

  In addition, since the profile of the tread portion 2 has a relatively flat shape, the ground contact area when the ground contact surface 3 is grounded can be increased. Moreover, since the thickness of the side rubber 9 of the sidewall portion 8 is reduced, the spring constant of the pneumatic tire 1 in the tire radial direction can be reduced. Thereby, the side wall part 8 can be made to bend easily at the time of load load, and, thereby, can also increase a ground contact area. Since the pneumatic tire 1 according to the present embodiment can increase the ground contact area as described above, the braking performance at the time of braking of the vehicle can be ensured. Further, by making the sidewall portion 8 easy to bend when a load is applied, making the sidewall portion 8 easy to bend can increase the contribution ratio of the sidewall portion 8 when the pneumatic tire 1 is deformed, and the tread portion Since the energy loss at 2 can be relatively reduced, the rolling resistance can be reduced.

  Further, since the tie rubber 40 disposed between the carcass layer 10 and the inner liner 16 is disposed so as to overlap the turn-up portion 12 of the carcass layer 10, the side wall portion 8 is loaded by a load. When the bead portion 30 is bent, it is possible to suppress the bending method from changing significantly between the position where the turn-up portion 12 is disposed and the position where the turn-up portion 12 is not disposed. That is, since the sidewall portion 8 has a low rigidity due to the reduced thickness of the side rubber 9, the side wall portion 8 is flexibly bent with respect to a load. For this reason, when the sidewall portion 8 or the bead portion 30 bends due to a load, the turn-up portion 12 is disposed after the turn-up portion 12 is not disposed and the portion having low rigidity is bent, and the carcass main body is disposed. The portion where the rigidity is high due to the overlap of the portion 11 and the turn-up portion 12 bends. However, since the rigidity is greatly different in both portions, the bending method with respect to the load is easily changed.

  The tie rubber 40 is disposed between the sidewall portion 8 and the bead portion 30 in which the way of bending with respect to the load is greatly changed as described above, and the bead core in which the turnup portion 12 and the carcass main body portion 11 are in contact with each other. It is not disposed up to the position of the outer end portion 32 of 31 but overlaps the turnup portion 12. For this reason, the turn-up portion 12 is disposed so that the two pieces of the turn-up portion 12 and the carcass body portion 11 overlap, and the turn-up portion 12 is not disposed and only one of the carcass body portion 11 is disposed. It is possible to suppress a sudden change in rigidity at the boundary with the portion where the is disposed, and it is possible to suppress a difference in rigidity between both portions from becoming too large. Thereby, the fall of the steering performance resulting from the way of bending abruptly changing at the time of load load can be suppressed.

  Further, the tie rubber 40 disposed between the carcass layer 10 and the inner liner 16 has an overlap amount H1 with respect to the turn-up portion 12 in the range of 20% to 60% of the turn-up width Ht. It can suppress more reliably that the bending method of the side wall part 8 or the bead part 30 changes rapidly at the time of load loading. That is, when the overlap amount H1 of the tie rubber 40 with respect to the turn-up portion 12 is less than 20% of the turn-up width Ht, the overlap amount H1 is too small, and therefore the position where the turn-up portion 12 is disposed. It is difficult for the tie rubber 40 to suppress a sudden change in rigidity at the boundary with the position where the turnup portion 12 is not disposed. In this case, it is difficult to suppress a sudden change in the bending method of the sidewall portion 8 and the bead portion 30 when a load is applied. Further, when the overlap amount H1 of the tie rubber 40 with respect to the turn-up portion 12 is larger than 60% of the turn-up width Ht, the overlap amount H1 is too large, and therefore the position where the turn-up portion 12 is disposed. It is difficult to suppress an excessively large difference in rigidity from the position where the turn-up portion 12 is not disposed. In this case, since the rigidity difference is too large, it is difficult to suppress a sudden change in the way of bending the sidewall portion 8 and the bead portion 30 when a load is applied. In addition, when the overlap amount H1 of the tie rubber 40 with respect to the turnup portion 12 is larger than 60% of the turnup width Ht, the range in which the tie rubber 40 is disposed becomes large. There is a risk that it will be difficult to achieve the above.

  On the other hand, when the overlap amount H1 of the tie rubber 40 with respect to the turn-up portion 12 is in the range of 20% to 60% of the turn-up width Ht, the rigidity change applied from the sidewall portion 8 to the bead portion 30 is changed. It can be relaxed. That is, the change in rigidity applied from the position outside the turn-up portion 12 in the tire radial direction to the position where the turn-up portion 12 is disposed can be moderated. As a result, it is possible to more reliably suppress a sudden change in the bending method of the sidewall portion 8 and the bead portion 30 when a load is applied, and to improve the riding comfort performance resulting from the rapid change in the bending method. It is possible to more reliably suppress the deterioration of the steering performance. As a result, the steering performance can be improved while suppressing the deterioration of the braking performance and the deterioration of the rolling resistance.

  Further, since the thickness Gt of the tie rubber 40 at the position of the tie rubber terminal portion 41 and the thickness Gi of the inner liner 16 at the position adjacent to the tie rubber terminal portion 41 are in a relationship of Gt ≦ Gi, It can be more reliably suppressed that the difference in rigidity between the position where the tire rubber 40 is disposed and the position inside the tire diameter where the tie rubber 40 is disposed is too large. As a result, the steering performance can be improved more reliably.

  In addition, by making the thickness Gt of the tie rubber 40 at the position of the tie rubber terminal portion 41 smaller than the thickness Gi of the inner liner 16 at a position adjacent to the tie rubber terminal portion 41, the pneumatic tire 1 Intrusion of air during production can be suppressed. That is, when the thickness Gt of the tie rubber 40 is too thick, there is a possibility that the gap between the inner liner 16 and the carcass layer 10 becomes too large inside the tire radial direction at the position where the tie rubber 40 is disposed. In this case, when the inner liner 16, the tie rubber 40, and the carcass layer 10 are bonded to each other at the time of manufacturing the pneumatic tire 1, air may enter a position where the tie rubber 40 is not disposed, and the adhesion between the members may be reduced. . On the other hand, by making the thickness Gt of the tie rubber 40 thinner than the thickness Gi of the inner liner 16, the entry of air at the time of manufacture due to the thickness Gt of the tie rubber 40 becoming too thick. Can be suppressed. As a result, the adhesion between members can be improved.

  Moreover, since the tread radius TR of the tread portion 2 in the tire meridian section is in the range of 600 mm or more and 1700 mm or less, the contact area can be ensured more reliably. That is, when the tread radius TR of the tread portion 2 is less than 600 mm, it may be difficult to secure a ground contact area when the ground contact surface 3 is grounded, and it may be difficult to secure braking performance. In addition, when the tread radius TR of the tread portion 2 is larger than 1700 mm, there is a possibility that the grounding property near the tire equator surface CL may be lowered when the grounding surface 3 is grounded, and it may be difficult to ensure the braking performance. is there.

  On the other hand, when the tread radius TR of the tread portion 2 is in the range of 600 mm or more and 1700 mm or less, the ground contact area when the ground contact surface 3 is grounded can be ensured more reliably. As a result, the braking performance can be ensured more reliably.

  Moreover, since the contact width TW of the tread portion 2 is in the range of 60% or more and 90% or less of the tire maximum width SW, the contact area can be ensured more reliably. That is, when the contact width TW of the tread portion 2 is less than 60% of the maximum tire width SW, it may be difficult to secure a contact area when the contact surface 3 is grounded, and it is difficult to ensure braking performance. There is a fear. In addition, when the contact width TW of the tread portion 2 is larger than 90% of the maximum tire width SW, the contact performance near the shoulder portion 5 is increased, but the contact performance near the tire equatorial plane CL may be reduced. There is a risk that it may be difficult to ensure the braking performance.

  On the other hand, when the contact width TW of the tread portion 2 is in the range of 60% or more and 90% or less of the tire maximum width SW, it is possible to more surely secure the contact area when the contact surface 3 contacts the ground. it can. As a result, the braking performance can be ensured more reliably.

  Moreover, since the height HW in the tire radial direction from the rim diameter reference position BL to the tire maximum width position W is in the range of 50% to 60% with respect to the tire cross-section height SH, the durability is reduced. While suppressing, it is possible to ensure the braking performance and the low rolling resistance more reliably. That is, the tire maximum width position W is the most flexible portion in the sidewall portion 8, but the height HW in the tire radial direction from the rim diameter reference position BL to the tire maximum width position W is the tire cross-section height SH. If it is less than 50%, the tire maximum width position W may be too close to the bead portion 30. In the vicinity of the bead portion 30, the carcass main body portion 11 and the turnup portion 12 are overlapped so that the rigidity is high and the portion is difficult to bend. Therefore, if the tire maximum width position W is too close to the bead portion 30, the tire It may be difficult to effectively reduce the spring constant in the radial direction. In this case, it becomes difficult to bend the sidewall portion 8 when the load is applied to increase the ground contact area, or to increase the contribution ratio of the sidewall portion 8 when the pneumatic tire 1 is deformed by the load. There is a fear. Further, 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-section 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 become unreasonable and durability may be reduced.

  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% to 60% with respect to the tire cross-section height SH, It can suppress that the large position W approaches the bead part 30 and the tread part 2 too much. Thereby, the spring constant in the tire radial direction of the pneumatic tire 1 can be more reliably reduced while suppressing a decrease in durability. As a result, it is possible to more reliably suppress a reduction in braking performance and a deterioration in rolling resistance while suppressing a decrease in durability.

  Further, since the thickness Gw of the side rubber 9 at the tire maximum width position W is in the range of 1 mm or more and 4 mm or less, the sidewall portion 8 is more reliably braking performance and low rolling while suppressing a reduction in cut resistance. Resistance can be secured. In other words, when the thickness Gw of the side rubber 9 at the tire maximum width position W is less than 1 mm, the thickness Gw of the side rubber 9 is too thin, so that an obstacle such as a stone is damaged when the obstacle contacts the side wall portion 8. There is a possibility that the cut resistance, which is difficult, may be reduced. Further, when the thickness Gw of the side rubber 9 at the tire maximum width position W exceeds 4 mm, the thickness Gw of the side rubber 9 is too thick, so that it may be difficult to effectively reduce the spring constant in the tire radial direction. is there. In this case, it becomes difficult to bend the sidewall portion 8 when the load is applied to increase the ground contact area, or to increase the contribution ratio of the sidewall portion 8 when the pneumatic tire 1 is deformed by the load. There is a fear.

  On the other hand, when the thickness Gw of the side rubber 9 at the tire maximum width position W is in the range of 1 mm or more and 4 mm or less, the spring constant in the tire radial direction of the pneumatic tire 1 is set while ensuring cut resistance. It can be reduced more reliably. As a result, it is possible to more reliably suppress a reduction in braking performance and a deterioration in rolling resistance while suppressing a decrease in cut resistance.

  Further, the tread rubber 4 has a thickness Gc at the center position and a thickness Gs at the shoulder position within the range of 2% to 10% of the tire cross-section height SH. While ensuring, the grounding area at the time of grounding of the grounding surface 3 can be ensured more reliably. That is, if the thickness Gc at the center position of the tread rubber 4 or the thickness Gs at the shoulder position is less than 2% of the tire cross-section height SH, the thickness of the tread rubber 4 is too thin, resulting in poor wear life. There is a risk that it becomes sufficient and it becomes difficult to ensure durability. Further, when 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-section height SH, the thickness of the tread rubber 4 is too thick. There is a possibility that the outer curvature rigidity becomes high and it is difficult to effectively increase the ground contact area when the ground surface 3 is grounded. In this case, it may be difficult to ensure the braking performance when the vehicle is braked.

  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% to 10% of the tire cross-section height SH, the wear life of the tread portion 2 is reduced. By suppressing the increase in the out-of-plane bending rigidity of the tread portion 2 while ensuring, the ground contact area at the time of ground contact of the ground contact surface 3 can be ensured more reliably. As a result, it is possible to more reliably suppress a decrease in braking performance while suppressing a decrease in durability.

  Furthermore, since the thickness Gc at the center position and the thickness Gs at the shoulder position satisfy the relationship Gc ≧ Gs, the tread rubber 4 can easily bend the vicinity of the ground contact end T in the tread portion 2. The portion near the shoulder portion 5 on the ground surface 3 can be easily grounded. As a result, the ground contact area can be increased more reliably, and a decrease in braking performance can be suppressed.

  Moreover, since the braking performance can be ensured by configuring the thickness of the tread rubber 4 as described above, the cap rubber 4a having a low tan δ can be used. As a result, hysteresis loss can be reduced, and rolling resistance can be more reliably reduced.

  Further, the turn-up portion 12 of the carcass layer 10 has a height TUH in the tire radial direction from the rim diameter reference position BL to the turn-up edge portion 12a within a range of 10% to 40% of the tire cross-section height SH. Therefore, the braking performance and the low rolling resistance can be more reliably ensured while ensuring the rigidity of the bead portion 30. In other words, when the height TUH from the rim diameter reference position BL to the turn-up edge portion 12a is less than 10% of the tire cross-section height SH, the rigidity of the bead portion 30 becomes insufficient, and the sidewall is loaded when a load is applied. There is a possibility that the range from the portion 8 to the bead portion 30 is excessively bent. In this case, since the deflection is too large, it may be difficult to secure the steering performance. When the height TUH from the rim diameter reference position BL to the turn-up edge portion 12a exceeds 40% of the tire cross-section height SH, the height TUH 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 spring constant in the tire radial direction. In this case, it becomes difficult to bend the sidewall portion 8 when the load is applied to increase the ground contact area, or to increase the contribution ratio of the sidewall portion 8 when the pneumatic tire 1 is deformed by the load. There is a fear.

  On the other hand, when the height TUH from the rim diameter reference position BL to the turn-up edge portion 12a is within the range of 10% to 40% of the tire cross-section height SH, the rigidity of the bead portion 30 is ensured. On the other hand, the spring constant of the pneumatic tire 1 in the tire radial direction can be more reliably reduced. As a result, the steering performance can be improved while more reliably suppressing the deterioration of the braking performance and the deterioration of the rolling resistance.

[Modification]
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. However, 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. For example, as shown in FIG. 5, the bead wires 33 of the bead core 31 are arranged in layers from the inner side to the outer side in the tire radial direction from the inner side to the outer side in four rows. A structure in which a total of six layers including a layer including a portion, a layer including a peripheral portion of three rows, a layer including a peripheral portion of two rows, and a layer including a peripheral portion of one row may be stacked. That is, the laminated structure of the bead wires 33 may be a 4 + 5 + 4 + 3 + 2 + 1 structure. Thus, even when the bead wires 33 are laminated in six layers, the outer shape 34 of the bead core 31 in the tire meridional 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. Preferably, it is formed in the outer diameter side wedge shape.

  FIG. 6 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram of a modified example in which the bead wires 33 are laminated in five layers. Further, even when the bead wires 33 of the bead core 31 are laminated in five layers, as shown in FIG. 6A, the bead wires 33 may have a stacked 5 + 4 + 3 + 2 + 1 structure. As shown in FIG. A stacked 4 + 4 + 3 + 2 + 1 structure may be used. 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. It may be a 4 + 4 + 3 + 2 + 1 structure that is not stacked but stacked in series. 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. Are stacked.

  Each of the structures shown in FIG. 6 is at least partially stacked in a stack, so that the bead wires 33 are arranged more densely than the bead wires 33 having a structure in which the whole is stacked in series. The filling rate can be increased. Thereby, the mass of the pneumatic tire 1 can be reduced and the performance can be exerted in a well-balanced manner while ensuring the rigidity and pressure resistance performance of the bead portion 30 and maintaining the running performance.

  When attention is paid to the filling rate of the bead wires 33, it is preferable that all the bead wires 33 are stacked in a stacked manner as shown in FIGS. 6 (a) and 6 (b). Further, with respect to the shape of the bead core 31, in order to increase the stability of the shape of the entire bead core 31, it is preferable that the shape of the entire bead core 31 is axisymmetric with respect to the center of the bead core 31 in the tire width direction. From this viewpoint, the shapes as shown in FIGS. 6A and 6C are preferable.

  FIG. 7 is a modified example of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram of a modified example in which the bead wires 33 are laminated in six layers. In addition, when the bead cores 33 of the bead core 31 are laminated in six layers, as shown in FIG. 7A, two layers each having a 3 + 4 + 4 + 3 + 2 + 1 structure and stacked in four rows are laminated. In this case, the structure may be shifted in the tire width direction. 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 piled up. Instead, it may be a 3 + 4 + 4 + 3 + 2 + 1 structure stacked in series. Since the laminated structure of the bead wires 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 overall structure of the pneumatic tire 1 and important characteristics. It is preferable to do this.

  In the above-described embodiment, the method of the carcass layer 10 passing through the tie rubber terminal portion 41 that defines the thickness Gt of the tie rubber 40 and the direction of the thickness Gi of the inner liner 16 at a position adjacent to the tie rubber terminal portion 41. The line Lc substantially coincides with the tie rubber terminal reference line Lt, but the normal Lc of the carcass layer 10 that defines the direction of the thickness Gt of the tie rubber 40 and the thickness Gi of the inner liner 16 is the tie rubber terminal reference line Lt. And the angle may be different. That is, the tie rubber terminal portion reference line Lt is an imaginary line parallel to the turnup portion inner reference line Lui, which is the normal line of the carcass main body portion 11 passing through the outer end portion 32 of the bead core 31, but the outer side of the bead core 31. When the inclination angle with respect to the tire radial direction of the carcass main body portion 11 at a position adjacent to the end portion 32 and the inclination angle with respect to the tire radial direction of the carcass main body portion 11 at a position adjacent to the tie rubber terminal portion 41 are different, tie rubber The normal line Lc of the carcass layer 10 that defines the direction of the thickness Gt of 40 or the thickness Gi of the inner liner 16 and the tie rubber terminal portion reference line Lt may have different angles.

  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 or a thermoplastic elastomer composition obtained by blending an elastomer component in a thermoplastic resin.

  Examples of the thermoplastic resin include polyamide-based 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 Polymer, 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 / P I copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystalline polyester, aromatic polyester such as polyoxyalkylene diimide diacid / polybutylene terephthalate copolymer], polynitrile resin (for example, polyacrylonitrile ( PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / styrene copolymer, methacrylonitrile / styrene / butadiene copolymer], poly (meth) acrylate resin [eg polymethacryl Acid methyl (PMMA), polyethyl methacrylate, ethylene ethyl acrylate copolymer (EEA), ethylene acrylic acid copolymer (EAA), ethylene methyl acrylate resin (EMA)], polyvinyl resin [eg, 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 Coalesced], cellulose resins [eg cellulose acetate, cellulose acetate butyrate], fluorine resins [eg polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer Combined (ETFE)], imide-based resin [for example, aromatic polyimide (PI)] and the like can be employed.

  Examples of elastomers include diene rubbers and hydrogenated products thereof (eg, NR, IR, epoxidized natural rubber, SBR, BR (high cis BR and low cis BR), NBR, hydrogenated NBR, hydrogenated SBR), olefins Rubber (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 copolymer, acrylic rubber (ACM), Ionomer, halogen-containing rubber [for example, brominated product of Br-IIR, Cl-IIR, 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 [eg methyl vinyl silicone rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber], sulfur-containing rubber [eg polysulfide rubber], fluoro rubber [eg vinylidene fluoride rubber] , Fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicon rubber, fluorine-containing phosphazene rubber), thermoplastic elastomers (for example, styrene elastomer, olefin elastomer, polyester elastomer, urethane elastomer, polyamide) Based elastomers] and the like may be employed.

  When the inner liner 16 is composed of a thermoplastic resin or a thermoplastic elastomer composition, the inner liner 16 is thinner than when the inner liner 16 is composed of a rubber composition mainly composed of butyl rubber. Can be Thereby, a tire weight can be reduced significantly.

  In the embodiment described above, 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 formed on the sidewalls on both sides in the tire width direction. It does not need 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. The tie rubber 40 may be divided at a position on the inner side in the tire radial direction of the layer 14. The tie rubber 40 only needs to be disposed at least between the carcass layer 10 and the inner liner 16 located in the sidewall portion 8, regardless of whether the tie rubber 40 is continuous or divided between the sidewall portions 8. First, the position of the tie rubber terminal portion 41 in the tire radial direction is located between the turn-up edge portion 12a of the turn-up portion 12 and the outer end portion 32 of the bead core 31, and the tie rubber 40 is the tire with respect to the turn-up portion 12. What is necessary is just to be arrange | positioned by overlapping in radial direction.

[Example]
8A to 8C are tables showing the results of performance evaluation tests for pneumatic tires. Hereinafter, with respect to the pneumatic tire 1 described above, 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. The performance evaluation test was conducted on braking performance, rolling resistance, and steering stability.

  In the performance evaluation test, a pneumatic tire 1 having a tire size specified by JATMA of 205 / 60R16 92V size is assembled on a rim wheel of JATMA standard with a rim size of 16 × 6.0J, and the air pressure is adjusted to 180 kPa. went.

  As for the evaluation method of each test item, the braking performance is 100 km / h on a dry road surface test course with a test tire attached to a front-wheel drive test vehicle with a displacement of 1500 cc and a load equivalent to two passengers. The braking distance from the speed to the start of braking until it completely stopped was measured. For the braking performance, the reciprocal of the measured braking distance is indicated by an index with the prior art example 1 described later as 100. The larger the value, the shorter the braking distance and the better the braking performance.

  Regarding the rolling resistance, an indoor drum tester (drum diameter: 1707 mm) was used, and the rolling resistance coefficient was calculated under the conditions of a load of 4.8 kN and a speed of 80 km / h in accordance with ISO28580. The result was shown by the index | exponent which makes the reciprocal number of the rolling resistance coefficient of the prior art example mentioned later 100. The larger this index, the lower the rolling resistance.

  Further, the handling stability was evaluated by performing a feeling evaluation by a test driver when traveling on the test course with the above-described test vehicle equipped with a test tire, and expressing it by an index with a conventional example described later as 100. The larger this value, the better the steering stability including ride comfort performance.

  A performance evaluation test compares with the pneumatic tire of the conventional example which is an example of the conventional pneumatic tire, Examples 1-13 which are the pneumatic tire 1 which concerns on this invention, and the pneumatic tire 1 which concerns on this invention. It carried out about 15 types of pneumatic tires with the comparative example 1 which is a pneumatic tire. Among these, in the conventional pneumatic tire, the tie rubber terminal portion 41 is located on the inner side in the tire radial direction with respect to the outer end portion 32 of the bead core 31, and the overlap amount H1 with respect to the turn-up width Ht is larger than 60%. It has become. Moreover, although the tie rubber terminal part 41 is located in the tire radial direction outer side rather than the outer side edge part 32 of the bead core 31, the overlap amount H1 with respect to the turnup width Ht is less than 20%.

  On the other hand, in Examples 1 to 13, which are examples of the pneumatic tire 1 according to the present invention, the positions of the tie rubber terminal portions 41 in the tire radial direction are the turn-up edge portion 12a and the outer end portion 32 of the bead core 31. The overlap amount H1 with respect to the turn-up width Ht is in the range of 20% or more and 60% or less. Further, in the pneumatic tire 1 according to Examples 1 to 13, the relationship between the tie rubber 40 thickness Gt at the position of the tie rubber terminal portion 41 and the thickness Gi of the inner liner 16, the size of the tread radius TR, and the contact width TW / tire maximum width SW, tire maximum width position W height HW / tire section height SH, tire maximum width position W side rubber 9 thickness Gw, center tread rubber thickness Gc / tire Cross section height SH, thickness Gs of tread rubber 4 at shoulder position / tire cross section height SH, thickness Gc at center position of tread rubber 4 and thickness Gs at shoulder position, turnup portion 12 The height TUH / the tire cross-section height SH is different.

  As a result of performing performance evaluation tests using these pneumatic tires 1, as shown in FIGS. 8A to 8C, the pneumatic tires 1 according to Examples 1 to 13 have lower braking performance than the conventional example. The steering stability can be improved while suppressing the deterioration of rolling resistance and rolling resistance. That is, the pneumatic tire 1 according to Examples 1 to 13 can improve the steering performance while suppressing the deterioration of the braking performance and the deterioration of the rolling resistance.

DESCRIPTION OF SYMBOLS 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 Carcass layer 11 Carcass main body part 12 Turn-up part 12a Turn-up edge part 14 Belt layer 16 Inner liner 18 tire inner surface 20 land portion 25 circumferential groove 30 bead portion 31 bead core 32 outer end portion 33 bead wire 34 outer shape 35 apex 36 bottom side 40 tie rubber 41 tie rubber terminal portion

Claims (9)

A tread portion extending in the tire circumferential direction and formed in an annular shape and having tread rubber;
A pair of sidewall portions disposed on both sides of the tread portion;
A pair of bead portions disposed inside each tire radial direction of the pair of sidewall portions;
A bead core disposed in the bead portion;
A carcass layer spanned between the pair of bead portions;
An inner liner disposed on the tire inner surface along the carcass layer;
With
The carcass layer is formed continuously from the carcass main body portion spanned between the pair of bead portions, and folded back from the tire width direction inner side to the tire width direction outer side along the periphery of the bead core. A turn-up portion extending toward the sidewall portion side while contacting the carcass main body portion from the position of the outer end portion in the tire radial direction of the bead core,
A tie rubber is disposed between the carcass layer located in the sidewall portion and the inner liner,
The tie rubber has a tie rubber terminal portion, which is an end portion on the inner side in the tire radial direction, and is positioned on the inner side in the tire radial direction than a turn-up edge portion, which is an end portion on the outer side in the tire radial direction of the turn-up portion. It overlaps in the tire radial direction with respect to the part,
The overlap amount H1 of the tie rubber with respect to the turn-up portion is
A pneumatic tire characterized by being within a range of 20% or more and 60% or less of a turn-up width Ht that is a distance between the outer end portion of the bead core and the turn-up edge portion. The turn-up width Ht is
The normal line of the carcass layer passing through the outer end of the bead core is a turn-up portion inner reference line,
The distance between the turn-up portion inner reference line and the turn-up portion outer reference line when a line passing through the turn-up edge portion and parallel to the turn-up portion inner reference line is used as the turn-up portion outer reference line. ,
The overlap amount H1 is
2. The distance between the tie rubber terminal portion reference line and the turnup portion outer reference line when a line passing through the tie rubber terminal portion and parallel to the turnup portion inner reference line is used as a tie rubber terminal portion reference line. Pneumatic tire described in 2. A thickness Gt of the tie rubber at the position of the tie rubber terminal portion;
The thickness Gi of the inner liner at a position adjacent to the tie rubber terminal portion,
The pneumatic tire according to claim 1, wherein Gt ≦ Gi.   The pneumatic tire according to claim 3, wherein a thickness Gi of the inner liner is a thickness of the inner liner on a normal line of the carcass layer passing through the tie rubber terminal portion. The tread radius of the tread portion in the tire meridional section is in the range of 600 mm to 1700 mm,
The pneumatic tire according to any one of claims 1 to 4, wherein a contact width is in a range of 60% to 90% of a maximum tire width.   The height in the tire radial direction from the reference position inside the tire radial direction of the tire cross-sectional height to the maximum tire width position is in the range of 50% to 60% with respect to the tire cross-sectional height. The pneumatic tire according to any one of the above.   The thickness of the side rubber located in the tire width direction outside of the carcass layer in the tire maximum width position in the side wall part is in the range of 1 mm or more and 4 mm or less. Pneumatic tire.   The tread rubber has a thickness Gc at the center position and a thickness Gs at the shoulder position satisfying a 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 7, which is in a range of 2% to 10% of a tire cross-section height.   In the turn-up portion, the height in the tire radial direction from the reference position inside the tire radial direction of the tire cross-section height to the turn-up edge portion is in the range of 10% to 40% of the tire cross-section height. The pneumatic tire according to any one of claims 1 to 8.

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