JP7087597B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

In recent years, the weight of the bead portion has been reduced for the purpose of reducing the weight of the tire. As a conventional pneumatic tire relating to such a problem, the technique described in Patent Document 1 is known. In Patent Document 1, the weight of the tire is reduced by omitting the bead filler.

Japanese Unexamined Patent Publication No. 2008-149778

Here, in the pneumatic tire, the sidewall portion located between the tread portion having the ground contact surface that touches the road surface and the bead portion to which the rim heel fits has elasticity and connects both of them. It ensures ride comfort and steering stability when the vehicle is running. However, when the bead filler is omitted, the rigidity of the region from the bead portion to the sidewall portion tends to decrease. When the rigidity of the region from the bead portion to the sidewall portion is reduced, the sidewall portion bends too much when a large load is applied to the pneumatic tire in the tire radial direction, and the tire inner surface of the sidewall portion The position near the tread part and the position near the bead part may come into contact with each other.

For example, when a tire falls into a pothole, which is a dent on the road surface formed by a part of the road surface peeling off due to aged deterioration of the road, the load acting on the tire is the pothole on the outer surface of the tire. Concentrate near the part that touches the edge of the tire. In this case, a large load acts due to the concentration of the load near the portion in contact with the edge of the pot hole, and the sidewall portion greatly bends in the tire radial direction due to this large load, and is closer to the tread portion on the inner surface of the tire. The position of the tire and the position near the bead part come into contact with each other. When the position near the tread part and the position near the bead part on the inner surface of the tire come into contact, the carcass located at this part is pinched by the road surface and the rim flange with a strong force, and the carcass cord is cut, so-called pinch cut. It may occur.

In this way, if the bead filler is omitted in order to reduce the weight of the tire, pinch cut may occur due to a decrease in the rigidity of the region from the bead portion to the sidewall portion, and there is room for improvement in that respect. was there.

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 suppressing a pinch cut while suppressing an increase in mass.

In order to solve the above-mentioned problems and achieve the object, the pneumatic tire according to the present invention is disposed of a tread portion extending in the tire circumferential direction and formed in an annular shape and on both sides of the tread portion. A pair of sidewall portions, 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 bead portions. With a carcass layer to be passed, the bead core consists of at least one bead wire wound in the tire circumferential direction, and at least one row in which a plurality of peripheral portions of the bead wire are aligned in the tire width direction in the tire meridional cross section. When a polygon formed by a common tangent line of a plurality of circumferential portions of the bead wire in the tire meridional cross section is used as the outer shape of the bead core, the outer shape is the tire. It has a single apex on the outer side in the radial direction, and the inner angle formed by the two sides sandwiching the apex is a sharp angle. From the folded portion that is bent and folded along the peripheral edge of the bead core in the bead portion and extends toward the sidewall portion while contacting the main body portion from the position of the tire radial outer end of the bead core. Therefore, in the range of 30% or more and 75% or less of the tire cross-sectional height from the reference position on the inner surface of the tire in the tire radial direction to the outside in the tire radial direction, the tire protrudes from the inner surface of the tire and the tire diameter. A ridge portion extending within a range in which the inclination angle in the tire circumferential direction with respect to the direction is 30 ° or more and 60 ° or less is formed, and the ridge portion has a plurality of the ridge portions in the extending direction of the ridge portion. It is characterized in that it is formed at intervals in orthogonal directions.

In the pneumatic tire, the convex portion is at least in a range of 30% or more and 45% or less of the tire cross-sectional height outward from the reference position in the tire radial direction, and the tire cross section outward from the reference position in the tire radial direction. It is preferably formed in the range of 60% or more and 75% or less of the height.

In the pneumatic tire, the height of the convex portion from the inner surface of the tire is preferably in the range of 2.0 mm or more and 4.0 mm or less.

In the pneumatic tire, the width of the convex portion in the direction orthogonal to the extending direction of the convex portion is preferably in the range of 3.0 mm or more and 10.0 mm or less.

In the pneumatic tire, it is preferable that the ridges have a pitch of 5 mm or more and 10 mm or less between adjacent ridges.

In the pneumatic tire, the sidewall portion is an average of portions located outside the tire width direction from the carcass layer in a range of 30% or more and 75% or less of the tire cross-sectional height outward from the reference position in the tire radial direction. It is preferable that the average side thickness, which is the thickness, is within the range of 1.0 mm or more and 2.5 mm or less.

The pneumatic tire according to the present invention has an effect that pinch cut can be suppressed while suppressing an increase in mass.

FIG. 1 is a cross-sectional view taken along the meridian showing a main part of a pneumatic tire according to an embodiment. FIG. 2 is a detailed view of part A of FIG. FIG. 3 is a detailed view of the bead core shown in FIG. FIG. 4 is a view taken along the line BB of FIG. FIG. 5 is a view taken along the line CC of FIG. FIG. 6 is an explanatory diagram of the sidewall portion shown in FIG. FIG. 7 is a schematic view showing a state in which an obstacle is in contact with the sidewall portion of the pneumatic tire according to the embodiment. FIG. 8 is a schematic view showing a state in which the inner portion of the ridge portion and the outer side portion of the ridge portion shown in FIG. 7 are in contact with each other. FIG. 9 is a modified example of the pneumatic tire according to the embodiment, and is an explanatory diagram of a case where a convex portion is partially formed. FIG. 10 is a modification of the pneumatic tire according to the embodiment, and is an explanatory diagram of a case where the cross-sectional shape of the convex portion is formed in the shape of a triangle. FIG. 11 is a modification of the pneumatic tire according to the embodiment, and is an explanatory diagram of a case where the cross-sectional shape of the convex portion is formed in the shape of a semicircle. FIG. 12 is a modification of the pneumatic tire according to the embodiment, and is an explanatory diagram of a case where the convex portions are formed discontinuously. FIG. 13 is a modification of the pneumatic tire according to the embodiment, and is an explanatory diagram when the bead wires are laminated in six layers. FIG. 14 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. 15 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. 16 is a chart showing the results of performance evaluation tests for pneumatic tires.

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. Further, 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 means 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. Further, the tire circumferential direction means a circumferential direction with the tire rotation axis as the central 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 a 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 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 equatorial line is a line on the tire equatorial plane CL and 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 taken along 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 formed in an annular shape on the outermost portion in the tire radial direction when viewed from the tire meridional cross section. The tread portion 2 has a tread rubber layer 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) on which the pneumatic tire 1 is mounted 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 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 oscillates in the tire width direction while extending in the tire circumferential 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.

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 on both sides of the pneumatic tire 1 in the tire width direction. ing. The sidewall portion 8 thus formed is a portion of the pneumatic tire 1 exposed to the outermost side in the tire width direction, and has the 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 radial direction of the tire. Similar to the sidewall portion 8, the bead portions 30 are arranged at two positions on both sides of the tire equatorial surface CL, that is, a pair of bead portions 30 are arranged on both sides of the tire equatorial surface 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 crossed belts 141 and 142 and a belt cover 143 are laminated. The pair of cross 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 crossed 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 cross each other in the inclination direction.

The pair of belt covers 143 are 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 have a belt angle defined as an inclination angle of the belt cord with respect to the tire circumferential direction. , Within a predetermined range (for example, 0 ° or more and 10 ° or less). In the present embodiment, the belt cover 143 is provided as a so-called belt edge cover, which is arranged only near the end portions of the pair of cross belts 141 and 142 in the tire width direction. 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 used in the tire circumferential direction with respect to the outer peripheral surfaces of the cross belts 141 and 142. It is composed of multiple windings and spiral winding. Further, the belt cover 143 may have a configuration other than this. The belt cover 143 may be arranged so as to cover the entire pair of crossing belts 141 and 142, or the belt cover 143 covering the entire crossing belts 141 and 142 and the tire widths of the crossing belts 141 and 142. A belt cover 143 disposed only in the vicinity of the direction end may be laminated.

A carcass layer 13 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 surface 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 13 has a single-layer structure composed of one carcass ply or a multilayer 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 13 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 carcus layer 13 is disposed. , 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 13 is folded back while bending along the peripheral edge of the bead core 31 at the main body portion 13a extending from the tread portion 2 to the bead portion 30 via the sidewall portion 8 and the tire diameter of the bead core 31. It is composed of a folded portion 13b extending toward the sidewall portion 8 side while contacting the main body portion 13a from the position of the outer end in the direction. Of these, the folded-back portion 13b is continuously formed from the main body portion 13a, and is folded back from the inside in the tire width direction to the outside in the tire width direction of the bead core 31 at the position where the bead core 31 is arranged in the bead portion 30. ..

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 13 spanning between the pair of bead portions 30 in this way. Further, the carcass ply of the carcass layer 13 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 disposed on the inner side in the tire radial direction and the outer side in the tire width direction of the rewinding portion of the bead core 31 and the carcass layer 13 in the bead portion 30.

Further, an inner liner 16 is formed along the carcass layer 13 on the inside of the carcass layer 13 or on the inner side of the carcass layer 13 in the pneumatic tire 1. The inner liner 16 is an air permeation prevention layer that is arranged on the inner surface of the tire and covers the carcass layer 13, suppresses oxidation due to exposure of the carcass layer 13, and prevents leakage of air filled in the tire. Further, the inner liner 16 is composed of, for example, a rubber composition containing butyl rubber as a main component, a thermoplastic resin, a thermoplastic elastomer composition in which an elastomer component is blended with the thermoplastic resin, and the like. Further, the inner liner 16 is adhered to the carcass layer 13 via a tie rubber (not shown), and forms a tire inner surface 18 which is an inner surface of the pneumatic tire 1.

FIG. 2 is a detailed view of part A of FIG. The bead core 31 is composed of at least one bead wire 32 wound in the tire circumferential direction, and the plurality of peripheral portions of the bead wire 32 overlap in the tire radial direction with at least one row in which the plurality of peripheral portions of the bead wire 32 are arranged in the tire width direction in the tire meridional cross section. Forming a layer. The bead core 31 may have a so-called single-winding structure in which a single bead wire 32 is continuously wound as long as a plurality of peripheral portions of the bead wire 32 form a row and a layer in the tire meridional cross section. Often, a so-called layer winding structure may be used in which a plurality of bead wires 32 are wound in a aligned state. In the present embodiment, a layer including three rows of orbital portions in order from the innermost side in the tire radial direction, 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. It has a structure in which a total of 5 layers including the peripheral portion of the tire are laminated. In the following description, such a laminated structure of bead wires 32 is referred to as "3 + 4 + 3 + 2 + 1 structure". Similarly, in the following description, the laminated structure of the bead wires 32 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 32 are laminated in a bale-like manner. In this case, "bale stacking" is a stacking method in which the centers of three peripheral 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 filling arrangement. Is.

FIG. 3 is a detailed view of the bead core 31 shown in FIG. Assuming that the polygon formed by the common tangents of the plurality of circumferential portions of the bead wire 32 in the tire meridional cross section is the outer shape 33 of the bead core 31, the outer shape 33 has a single apex 34 outward in the radial direction of the tire. And has a bottom 35 so as to face the apex 34 on the inner side in the radial direction of the tire. That is, in the present embodiment, the bead core 31 has a pentagonal outer shape 33 because the bead wire 32 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 34 of the outer shape 33, and the width of the bead core 31 as a whole 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".

Since the bead core 31 is formed in a wedge shape on the outer diameter side, the carcass layer 13 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 cross section of the tire meridian, the carcass layer 13 extending along the peripheral edge of the bead core 31 is also bent into a substantially pentagonal shape. Further, the portion of the folded portion 13b of the carcass layer 13 that is lateral to the tire radial direction of the bead core 31 along the main body portion 13a of the carcass layer 13 while in contact with the main body portion 13a of the carcass layer 13. It extends toward the sidewall portion 8 side. Therefore, in the bead portion 30, a closed region surrounding the bead core 31 is formed by the main body portion 13a and the folded portion 13b of the carcass layer 13.

In the closed region formed by the main body portion 13a and the folded portion 13b of the carcass layer 13, substantially only the bead core 31 is present. Therefore, the pneumatic tire 1 according to the present embodiment has a bead filler as used in a conventional pneumatic tire or a similar tire component (a main body of the carcass layer 13 arranged on the outer side in the tire radial direction of the bead core 31). A member that is wrapped by the portion 13a and the folded portion 13b 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 32 and a rubber that fills a slight gap formed between the bead core 31 and the carcass layer 13 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 in the closed region. Then, the rubber occupancy rate is in the range of 0.1% or more and 15% or less.

Further, in the pneumatic tire 1 according to the present embodiment, the convex portion 40 protruding from the tire inner surface 18 is formed on the tire inner surface 18. The ridge portion 40 is formed integrally with the inner liner 16 by the same member as the rubber composition or the like constituting the inner liner 16. Further, the ridge portion 40 is formed on the inner surface 18 of the tire in a range of 30% or more and 75% or less of the tire cross-sectional height SH from the reference position on the inner side of the tire cross-sectional height SH in the tire radial direction to the outer side in the tire radial direction. There is. In this case, the tire cross-sectional height SH 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 baseline BL. The rim baseline BL referred to here is a tire axial line that passes through the rim diameter defined by the JATTA standard.

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. The normal internal pressure referred to here 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. Since the tire cross-sectional height SH is defined in this way, the rim baseline BL is the reference position on the inner side of the tire cross-sectional height SH in the tire radial direction.

FIG. 4 is a view taken along the line BB of FIG. The convex portion 40 formed on the inner surface 18 of the tire extends within a range in which the inclination angle θr in the tire circumferential direction with respect to the tire radial direction is 30 ° or more and 60 ° or less. Further, the ridges 40 are formed by arranging a plurality of ridges 40 in parallel at intervals in a direction orthogonal to the extending direction of the ridges 40. That is, a plurality of the convex portions 40 are arranged side by side via the concave portions 41 formed in the shape of a groove. The widths of the plurality of ridges 40 are substantially constant, and the distance between adjacent ridges 40 is also substantially constant.

FIG. 5 is a view taken along the line CC of FIG. The ridge portion 40 has a substantially rectangular cross-sectional shape when viewed in the extending direction of the ridge portion 40, and the height Hr from the tire inner surface 18 is 2.0 mm or more and 4.0 mm or less. It is within the range. Further, the ridge portion 40 has a width Wr in a direction orthogonal to the extending direction of the ridge portion 40 within a range of 3.0 mm or more and 10.0 mm or less. Further, in the ridges 40, the pitch Pr between the ridges 40 adjacent to each other via the recess 41 is within the range of 5 mm or more and 10 mm or less, and the distance Br between the ridges 40 adjacent to each other is 1. It is within the range of 0.0 mm or more and 5.0 mm or less. In this case, the pitch Pr between the ridges 40 is the distance between the centers in the direction of the width Wr of the ridges 40. Further, the height Dc of the ridge portion 40 from the carcass layer 13 at the position where the ridge portion 40 is arranged is within the range of 1.0 mm or more and 5.0 mm or less.

In this case, the tire inner surface 18 refers to a portion of the inner surface of the pneumatic tire 1 in which the convex portion 40 is not formed. The tire inner surface 18 is also provided as the bottom of the recess 41 formed between the adjacent convex portions 40. Therefore, the height Hr of the convex portion 40 is also the height from the bottom of the concave portion 41.

FIG. 6 is an explanatory diagram of the sidewall portion 8 shown in FIG. The sidewall portion 8 is the average thickness of the portion located outside the tire width direction from the carcass layer 13 in the range of 30% or more and 75% or less of the tire cross-sectional height SH outside the tire radial direction from the rim baseline BL. The average side thickness is within the range of 1.0 mm or more and 2.5 mm or less. That is, the side rubber 9 is mainly arranged in the portion of the sidewall portion 8 located outside the carcass layer 13 in the tire width direction, and the side rubber 9 is arranged at the position of the sidewall portion 8 outside in the tire radial direction. The tread rubber layer 4 overlaps with the tread rubber layer 4. The average side thickness is the average thickness of the side rubber 9 and the combined thickness of the side rubber 9 and the tread rubber layer 4.

Further, the sidewall portion 8 has a thickness Gi of the side rubber 9 located on the outer side in the tire width direction from the carcass layer 13 at a position 30% of the tire cross-sectional height SH on the outer side in the tire radial direction from the rim baseline BL. It is within the range of 1.5 mm or more and 4.0 mm or less. Further, the sidewall portion 8 includes a side rubber 9 and a tread rubber layer 4 located on the outer side in the tire width direction from the carcass layer 13 at a position 75% of the tire cross-sectional height SH on the outer side in the tire radial direction from the rim baseline BL. The combined thickness Go is within the range of 1.0 mm or more and 3.0 mm or less. Further, in the sidewall portion 8, the thickness Gm of the side rubber 9 located outside the carcass layer 13 at the tire maximum width position P in the tire width direction is within the range of 1.0 mm or more and 3.0 mm or less. In this case, the maximum tire width position P is the sidewall portion 8 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. This is the position in the tire radial direction where the dimension in the tire width direction is maximum excluding the structure protruding from the outer surface of the tire.

When the pneumatic tire 1 according to the present embodiment is mounted on a vehicle, the pneumatic tire 1 is rim-assembled on 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 in 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. Drive while driving. This makes it easier for the ground contact surface 3 to 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.

At that time, in the pneumatic tire 1 according to the present embodiment, the folded portion 13b of the carcass layer 13 is in contact with the main body portion 13a from the position of the tire radial outer end of the bead core 31 toward the sidewall portion 8 side. It extends, and the so-called bead filler used in a general pneumatic tire is not arranged on the outer side of the bead core 31 in the tire radial direction. The bead filler is a rubber member disposed over one circumference in the tire circumferential direction at a position outside the tire radial direction of the bead core 31, but the pneumatic tire 1 according to the present embodiment has a bead filler in the bead portion 30. Is not arranged, so the mass is reduced accordingly. Specifically, the rubber occupancy rate, which is the ratio of the total area a of the rubber existing in the closed region to the area A of the closed region formed by the main body portion 13a and the folded portion 13b of the carcass layer 13, is 0. It is in the range of 1% or more and 15% or less, and the rubber occupancy in the closed region is small, so that the mass is reduced accordingly. Therefore, the pneumatic tire 1 has a small inertial force during rotation, and can improve fuel efficiency, steering stability, and braking performance. Further, since the mass is small, the followability to the unevenness of the road surface can be improved, and the riding comfort performance can be improved.

Further, since the pneumatic tire 1 receives the weight of the vehicle body and the load due to acceleration / deceleration and turning when the vehicle is running, a large load acts in the tire radial direction. This load is mainly received by the air filled inside the pneumatic tire 1, but is received not only by the air inside the pneumatic tire 1 but also by the tread portion 2, the sidewall portion 8, and the bead portion 30. That is, the sidewall portion 8 transmits the load between the bead portion 30 to which the rim wheel is fitted and the tread portion 2, and the tread portion 2 transmits the load between the sidewall portion 8 and the road surface. .. Therefore, a large load acts on the tread portion 2, the sidewall portion 8, and the bead portion 30 when the vehicle is running, and each of these portions receives this load while mainly bending in the tire radial direction.

In particular, in the pneumatic tire 1 in which the bead filler is not provided on the outer side of the bead core 31 in the tire radial direction, the rigidity of the sidewall portion 8 and the bead portion 30 in the tire radial direction is lower than that of the pneumatic tire having the bead filler. The sidewall portion 8 and the bead portion 30 are easily bent in the tire radial direction. For this reason, while the vehicle is running, the pneumatic tire 1 falls into the pothole which is a dent on the road surface, and the sidewall comes into contact with the outer surface of the sidewall portion 8. When an obstacle comes into contact with the outer surface of the portion 8 from an oblique direction, the sidewall portion 8 tends to be greatly bent by the force acting on the contact portion with the obstacle. When the position closer to the tread portion 2 and the position closer to the bead portion 30 on the inner surface 18 of the tire come into contact with each other due to the large bending of the sidewall portion 8, the carcass layer 13 located at the contacted portion becomes an obstacle and the rim flange. If the tire is pinched by a strong force, the carcass cord may be cut and a pinch cut may occur.

On the other hand, in the pneumatic tire 1 according to the present embodiment, since the convex portion 40 is formed on the inner surface 18 of the tire, pinch cut can be suppressed. FIG. 7 is a schematic view showing a state in which the obstacle G is in contact with the sidewall portion 8 of the pneumatic tire 1 according to the embodiment. In the pneumatic tire 1 according to the present embodiment, the convex portion 40 is formed on the inner surface 18 of the tire in a range of 30% or more and 75% or less of the tire cross-sectional height SH on the outer side in the tire radial direction from the rim baseline BL. Therefore, when the sidewall portion 8 is greatly bent, the ridge portion inner portion 45, which is a portion located closer to the bead portion 30 than the tire maximum width position P in the ridge portion 40, and the ridge portion 40. It is possible to bring the tire into contact with the outer portion 46 of the ridge portion, which is a portion located closer to the tread portion 2 than the maximum width position P of the tire. As a result, even when the obstacle G comes into contact with the outer surface of the sidewall portion 8 and the sidewall portion 8 is greatly bent, it is possible to prevent the tire inner surfaces 18 from directly contacting each other, and the carcass layer 13 can be prevented from coming into direct contact with each other. Is sandwiched between the obstacle G and the rim flange Rf with a strong force, so that the carcass cord can be prevented from being cut.

That is, when the portion of the sidewall portion 8 in contact with the obstacle G is sandwiched between the obstacle G and the rim flange Rf with a strong force, the convex portions 40 provided on the inner surface 18 of the tire come into contact with each other. Therefore, the force when the position closer to the tread portion 2 and the position closer to the bead portion 30 than the tire maximum width position P on the tire inner surface 18 side come into contact can be dispersed by the convex portion 40. Therefore, when the sidewall portion 8 is sandwiched between the obstacle G and the rim flange Rf with a strong force, a large force at the time of contact between the position closer to the tread portion 2 on the tire inner surface 18 side and the position closer to the bead portion 30. However, when the tire is transmitted from the inner surface 18 side of the tire to the carcass layer 13, it is possible to suppress the local transmission to the carcass layer 13 and alleviate the force acting on the carcass layer 13. As a result, when the sidewall portion 8 is sandwiched between the obstacle G and the rim flange Rf with a strong force, it is possible to prevent a large force from acting locally on the carcass cord of the carcass layer 13. , It is possible to prevent the carcass cord from being cut by a large local force.

FIG. 8 is a schematic view showing a state in which the inner portion 45 of the ridge portion and the outer portion 46 of the ridge portion shown in FIG. 7 are in contact with each other. The ridge portion 40 is formed so that the inclination angle in the tire circumferential direction with respect to the tire radial direction extends within a range of 30 ° or more and 60 ° or less. Therefore, due to the large bending of the sidewall portion 8, the inner portion 45 of the ridge portion 45, which is a portion located closer to the bead portion 30 than the maximum width position P of the tire in the ridge portion 40, and the tire in the ridge portion 40. When the outer portion 46 of the ridge portion, which is a portion located closer to the tread portion 2 than the maximum width position P, comes into contact with the inner portion 45 of the ridge portion and the outer portion 46 of the ridge portion, the extending direction is Contact with each other intersecting each other. Therefore, it is possible to prevent the ridge portion 40 from entering the recess 41 and the ridge portion 40 from coming into contact with the tire inner surface 18 at the time of contact between the ridge portion inner portion 45 and the ridge portion outer portion 46. The ridges 40 can be brought into contact with each other more reliably. As a result, when the sidewall portion 8 is sandwiched between the obstacle G and the rim flange Rf with a strong force, the force transmitted to the carcass layer 13 can be more reliably dispersed by the ridge portion 40.

Further, since the ridges 40 are formed at intervals in the direction orthogonal to the extending direction of the ridges 40, the ridges 40 disperse the force acting on the carcass layer 13 to exert the force. When the member to be relaxed is provided on the inner surface 18 of the tire, it is possible to suppress the increase in mass as much as possible by providing the member. As a result, pinch cut can be suppressed while suppressing the increase in mass.

Further, since the height Hr from the tire inner surface 18 of the convex portion 40 is within the range of 2.0 mm or more and 4.0 mm or less, it is more reliable that the carcass cord is cut while suppressing the increase in mass as much as possible. Can be suppressed. That is, when the height Hr of the ridge portion 40 is less than 2.0 mm, the height Hr of the ridge portion 40 is too low, so that the sidewall portion 8 is greatly bent and is convex with the ridge portion inner portion 45. When the outer surface portion 46 of the strip portion comes into contact with the outer surface portion 46, the force transmitted from the inner surface 18 side of the tire to the carcass layer 13 side may be difficult to disperse by the convex strip portion 40. In this case, it may be difficult to suppress the action of a large local force on the carcass cord, and it may be difficult to suppress the cutting of the carcass cord due to the large local force. Further, when the height Hr of the ridge portion 40 exceeds 4.0 mm, the height Hr of the ridge portion 40 is too high. Therefore, by providing the ridge portion 40 on the inner surface 18 of the tire, the mass increases. It may be easier.

On the other hand, when the height Hr of the ridge portion 40 is within the range of 2.0 mm or more and 4.0 mm or less, the tire inner surface 18 side is suppressed while suppressing the increase in mass due to the provision of the ridge portion 40 as much as possible. The force transmitted from the tire to the carcass layer 13 side can be more reliably dispersed by the ridge portion 40, and the carcass cord can be more reliably suppressed from being cut. As a result, pinch cut can be suppressed while suppressing the increase in mass more reliably.

Since the width Wr of the ridge portion 40 in the direction orthogonal to the extending direction of the ridge portion 40 is within the range of 3.0 mm or more and 10.0 mm or less, the carcass cord is cut while suppressing the increase in mass as much as possible. This can be suppressed more reliably. That is, when the width Wr of the ridge portion 40 is less than 3.0 mm, the width Wr of the ridge portion 40 is too narrow, so that the sidewall portion 8 is greatly bent and the ridge portion inner portion 45 and the ridge portion are formed. When the outer portion 46 comes into contact with the tire, the force transmitted from the inner surface 18 side of the tire to the carcass layer 13 side may be difficult to be dispersed by the ridge portion 40. In this case, it may be difficult to suppress the action of a large local force on the carcass cord, and it may be difficult to suppress the cutting of the carcass cord due to the large local force. Further, when the width Wr of the ridge portion 40 exceeds 10.0 mm, the width Wr of the ridge portion 40 is too wide, so that the mass is likely to increase by providing the ridge portion 40 on the inner surface 18 of the tire. There is a risk.

On the other hand, when the width Wr of the ridge portion 40 is within the range of 3.0 mm or more and 10.0 mm or less, the increase in mass due to the provision of the ridge portion 40 is suppressed as much as possible from the tire inner surface 18 side. The force transmitted to the carcass layer 13 side can be more reliably dispersed by the ridge portion 40, and the carcass cord can be more reliably suppressed from being cut. As a result, pinch cut can be suppressed while suppressing the increase in mass more reliably.

Further, since the ridges 40 have a pitch Pr between adjacent ridges 40 within a range of 5 mm or more and 10 mm or less, the increase in mass is suppressed as much as possible and the carcass cord is more reliably suppressed from being cut. can do. That is, when the pitch Pr between the adjacent convex portions 40 is less than 5 mm, the pitch Pr between the convex portions 40 is too narrow, so that the mass is increased by providing the convex portions 40 on the inner surface 18 of the tire. It may be easier to do. Further, when the pitch Pr between the adjacent convex portions 40 exceeds 10 mm, the pitch Pr between the convex portions 40 is too wide, so that the sidewall portion 8 is greatly bent and the inner portion 45 of the convex portion and the convex portion are convex. When the outer side portion 46 comes into contact with the outer portion 46, the force transmitted from the inner surface 18 side of the tire to the carcass layer 13 side may be difficult to disperse by the ridge portion 40. In this case, it may be difficult to suppress the action of a large local force on the carcass cord, and it may be difficult to suppress the cutting of the carcass cord due to the large local force.

On the other hand, when the pitch Pr between the adjacent convex portions 40 is within the range of 5 mm or more and 10 mm or less, the carcass from the tire inner surface 18 side while suppressing the increase in mass due to the provision of the convex portions 40 as much as possible. The force transmitted to the layer 13 side can be more reliably dispersed by the ridge portion 40, and the carcass cord can be more reliably suppressed from being cut. As a result, pinch cut can be suppressed while suppressing the increase in mass more reliably.

Further, the sidewall portion 8 has an average side thickness of a portion located on the outer side in the tire width direction from the carcass layer 13 in a range of 30% or more and 75% or less of the tire cross-sectional height SH on the outer side in the tire radial direction from the rim baseline BL. However, since it is within the range of 1.0 mm or more and 2.5 mm or less, it is possible to suppress the damage of the carcass layer 13 while suppressing the increase in mass more reliably. That is, when the average side thickness is less than 1.0 mm, the thickness of the portion of the sidewall portion 8 located outside the carcass layer 13 in the tire width direction is too thin, so that the outer surface of the sidewall portion 8 is covered. When the obstacle G comes into contact with the side rubber 9, the side rubber 9 may be easily cracked. In this case, the carcass layer 13 located in the sidewall portion 8 may be easily damaged from the outside in the tire width direction. If the average side thickness exceeds 2.5 mm, the thickness of the portion of the sidewall portion 8 located outside the carcass layer 13 in the tire width direction is too thick, so that the bead filler is not provided. It may be difficult to effectively reduce the mass.

On the other hand, when the average side thickness is within the range of 1.0 mm or more and 2.5 mm or less, the mass of the sidewall portion 8 is secured while ensuring the strength of the portion located outside the carcass layer 13 in the tire width direction. Can be effectively reduced. As a result, damage to the carcass layer 13 can be suppressed while more reliably suppressing the increase in mass.

[Modification example]
In the pneumatic tire 1 according to the above-described embodiment, the convex portion 40 is in the range of 30% or more and 75% or less of the tire cross-sectional height SH on the inner surface 18 of the tire from the rim baseline BL to the outside in the tire radial direction. Although it is formed, the convex portion 40 does not have to be formed in the entire range of 30% or more and 75% or less of the tire cross-sectional height SH on the outer side in the tire radial direction from the rim baseline BL. FIG. 9 is a modification of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram of a case where the convex portion 40 is partially formed. As shown in FIG. 9, the ridge portion 40 is not formed near the tire maximum width position P, and is located closer to the tread portion 2 and the bead portion 30 than the tire maximum width position P on the tire inner surface 18. It may be formed only at the position. The ridge portion 40 has at least a range H1 of 30% or more and 45% or less of the tire cross-sectional height outward from the rim baseline BL in the tire radial direction, and 60% of the tire cross-sectional height outward from the rim baseline BL in the tire radial direction. It suffices if it is formed in the range H2 of 75% or less.

The ridge portion 40 is formed in these ranges H1 and H2 on the inner surface 18 of the tire, so that when the sidewall portion 8 is largely bent, the ridge portion 40 is located inside the ridge portion 40 located in the range H1. Since the portion 45 and the convex portion outer portion 46, which is the convex portion 40 located in the range H2, come into contact with each other, the force transmitted from the tire inner surface 18 side to the carcass layer 13 side can be dispersed by the convex portion 40. .. As a result, it is possible to prevent the carcass cord from being cut. Further, by not forming the ridge portion 40 in the vicinity of the tire maximum width position P, it is possible to further suppress the increase in mass due to the provision of the ridge portion 40. As a result, pinch cut can be suppressed while suppressing the increase in mass more reliably.

Further, in the pneumatic tire 1 according to the above-described embodiment, the convex portion 40 has a substantially rectangular cross-sectional shape when viewed in the extending direction of the convex portion 40, but the convex portion 40. May be formed in any other shape. FIG. 10 is a modification of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram of a case where the cross-sectional shape of the convex portion 40 is formed into a triangular shape. FIG. 11 is a modification of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram of a case where the cross-sectional shape of the convex portion 40 is formed in a semicircular shape. As shown in FIG. 10, the ridge portion 40 may have a substantially triangular cross-sectional shape when viewed in the extending direction of the ridge portion 40, and as shown in FIG. 11, the ridge portion 40 may have a substantially triangular shape. The cross-sectional shape of the ridge portion 40 when viewed in the extending direction may be a substantially semicircular shape. The ridges 40 project from the inner surface 18 of the tire and extend within a range in which the inclination angle in the tire circumferential direction with respect to the tire radial direction is 30 ° or more and 60 ° or less, and a plurality of ridges 40 extend the ridges 40. The shape of each convex portion 40 does not matter as long as it is formed at intervals in the direction orthogonal to the existing direction.

Further, in the pneumatic tire 1 according to the above-described embodiment, the ridges 40 are continuously extended in the extending direction of the ridges 40, but the ridges 40 are continuously extended in the extending direction. It does not have to be. FIG. 12 is a modification of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram of a case where the convex portion 40 is formed discontinuously. For example, as shown in FIG. 12, the ridge portion 40 may be divided in the extending direction of the ridge portion 40 and may be formed discontinuously in the extending direction of the ridge portion 40. That is, the ridge portion 40 is formed discontinuously in the extending direction of the ridge portion 40, and has a gap portion 42 between adjacent ridge portions 40 in the extending direction of the ridge portion 40. May be good. In this case, it is preferable that the convex portions 40 adjacent to each other via the concave portion 41 in the width direction of the convex portion 40 are displaced in the extending direction of the convex portion 40. That is, the gaps 42 located at the ends of the convex portions 40 adjacent to each other via the concave portions 41 in the width direction of the convex portions 40 in the extending direction of the convex portions 40 are in the extending direction of the convex portions 40. It is preferable that they are out of alignment.

Further, when the convex portion 40 is formed discontinuously in the extending direction of the convex portion 40 in this way, the length Lr of the convex portion 40 in the extending direction of the convex portion 40 and the convex portion 40 are formed. The distance Lb between the convex portions 40 adjacent to each other in the extending direction of the portions 40, that is, the width Lb of the gap portion 42 is preferably within the range of 0.075 ≦ (Lb / Lr) ≦ 0.1.

Further, in the pneumatic tire 1 according to the above-described embodiment, the ridge portion 40 is formed integrally with the inner liner 16, but the ridge portion 40 is not formed integrally with the inner liner 16. You may. The ridge portion 40 may be formed as a member separate from the inner liner 16 and may be formed on the inner surface 18 of the tire by being attached to the inner liner 16 or the like.

Further, in the pneumatic tire 1 according to the above-described embodiment, the height of the convex portion 40 from the inner surface 18 of the tire and the height of the convex portion 40 from the bottom of the concave portion 41 are the same. These may be different. That is, the bottom of the recess 41 has a distance from the carcass layer 13 approximately the same as the distance from the carcass layer 13 at the portion located near the convex portion 40 on the inner surface 18 of the tire, but these are mutual. It may be different. For example, the distance from the carcass layer 13 to the bottom of the recess 41 may be larger than the distance from the carcass layer 13 to the tire inner surface 18. Even when the distance from the carcass layer 13 to the bottom of the recess 41 is larger than the distance from the carcus layer 13 to the tire inner surface 18, the formation of the recess 41 increases the mass when suppressing the pinch cut. Can be suppressed as much as possible.

Further, in the pneumatic tire 1 according to the above-described embodiment, the bead wire 32 of the bead core 31 has a laminated structure of 3 + 4 + 3 + 2 + 1, but the bead wire 32 may be laminated with another structure. FIG. 13 is a modification of the pneumatic tire 1 according to the embodiment, and is an explanatory diagram when the bead wires 32 are laminated in six layers. As shown in FIG. 13, for example, as shown in FIG. 13, the bead wire 32 of the bead core 31 has a layer including four rows of orbital portions, 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 two rows of orbital portions, and a layer including one row of the orbiting portion, are laminated. That is, the laminated structure of the bead wires 32 may be a 4 + 5 + 4 + 3 + 2 + 1 structure. In this way, even when the bead wires 32 are laminated in six layers, the outer shape 33 of the bead core 31 in the tire meridional cross section is a pentagon in which the apex 34 is located on the outer side in the tire radial direction and the base 35 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. 14 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 32 are laminated in five layers. Further, the bead wire 32 of the bead core 31 may have a 5 + 4 + 3 + 2 + 1 structure of bale stacking as shown in FIG. 14 (a) even when laminated in five layers, and as shown in FIG. 14 (b), the bale may be formed. It may have a stacking 4 + 4 + 3 + 2 + 1 structure, and as shown in FIG. 14 (c), 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. 14 (c), 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. 14 is laminated in a bale-like manner, the bead wires 32 are arranged more closely than the bead wires 32 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 by satisfactorily ensuring the rigidity and the pressure resistance performance of the bead portion 30.

Focusing on the filling factor of the bead wires 32, it is preferable that all the bead wires 32 are stacked in a bale shape as shown in FIGS. 14 (a) and 14 (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. 14 (a) and 14 (c) are preferable.

FIG. 15 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 32 are laminated in six layers. Further, when the bead wire 32 of the bead core 31 is laminated in 6 layers, as shown in FIG. 15A, the bead wire 32 has a 3 + 4 + 4 + 3 + 2 + 1 structure of bale stacking, and two layers including four rows of circumferential portions are laminated. The structure may be shifted in the tire width direction, and as shown in FIG. 15 (b), 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. Instead, the structure may be 3 + 4 + 4 + 3 + 2 + 1 stacked in series. Since the laminated structure of the bead wire 32 possessed by 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.

[Example]
FIG. 16 is a chart showing the results of performance evaluation tests for pneumatic tires. 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. In the performance evaluation test, the pinch cut resistance, which is the performance regarding the difficulty of occurrence of pinch cut, and the mass of the pneumatic tire 1 were tested.

The performance evaluation test was carried out using a pneumatic tire 1 having a tire nominal size of 205 / 55R16 specified by JATTA. For the evaluation method of each test item, for pinch cut resistance, the test tire is rim-assembled on a JATTA standard rim wheel with a rim size of 16 x 7.0 J, the air pressure is filled to 230 kPa, and then the test vehicle is used. It was investigated whether or not there was a puncture due to a pinch cut when the vehicle was mounted and the vehicle was run, and when the vehicle was made to approach a curb with a height of 110 mm at an angle of 30 ° and passed over. The pinch cut resistance was expressed by an index of 100 as the conventional example described later, in which the difficulty of occurrence of pinch cut was evaluated by performing this test with 10 test tires having the same configuration. The larger the index value, the less likely it is that pinch cut will occur, indicating that the pinch cut resistance is excellent.

Further, the mass of the pneumatic tire 1 was measured by measuring 5 tires each having the same configuration, and the average value of the measured masses was expressed as an index with the conventional example 1 described later as 100. As for the mass of the pneumatic tire 1, the smaller this value is, the lighter the mass per tire is, and it is shown that the mass is excellent in terms of weight reduction. It is assumed that the mass is within the permissible range of the increase in mass if the index is 101 or less even when the mass is increased as compared with the conventional example, and the increase in mass is suppressed.

The performance evaluation test compares a conventional pneumatic tire which is an example of a conventional pneumatic tire, Examples 1 to 8 which are the pneumatic tire 1 according to the present invention, and the pneumatic tire 1 according to the present invention. Eleven types of pneumatic tires with Comparative Examples 1 and 2 which are pneumatic tires were used. Of these, the pneumatic tire of the conventional example is not provided with the bead filler, and the convex portion 40 is not formed on the inner surface 18 of the tire. Further, in Comparative Examples 1 and 2, a bead filler is provided in each of the comparative examples 1, the ridge portion 40 is not formed on the inner surface 18 of the tire in the comparative example 1, and the ridge 40 is not formed on the inner surface 18 of the tire in the comparative example 2. The portion 40 is formed.

On the other hand, in Examples 1 to 8, which are examples of the pneumatic tire 1 according to the present invention, the bead filler is not provided, and the convex portion 40 is formed on the inner surface 18 of the tire. Further, in the pneumatic tire 1 according to the first to eighth embodiments, the height Hr of the ridge portion 40, the width Wr of the ridge portion 40, the pitch Pr of the ridge portion 40, and the region where the ridge portion 40 is arranged. The average side thickness in each is different.

As a result of performing a performance evaluation test using these pneumatic tires 1, as shown in FIG. 16, the pneumatic tires 1 according to Examples 1 to 8 suppress the increase in mass as compared with the conventional examples, while suppressing the increase in mass. It was found that the pinch cut resistance can be improved. That is, the pneumatic tire 1 according to the first to eighth embodiments can suppress the pinch cut while suppressing the increase in mass.

1 Pneumatic tire 2 Tread part 3 Ground surface 4 Tread rubber layer 5 Shoulder part 8 Side wall part 9 Side rubber 13 Carcass layer 13a Main body part 13b Folded part 14 Belt layer 16 Inner liner 17 Rim cushion rubber 18 Tire inner surface 20 Land part 25 laps Directional groove 30 Bead part 31 Bead core 32 Bead wire 33 Outer shape 34 Top 35 Bottom 40 Convex part 41 Concave part 42 Void part 45 Convex part Inner part 46 Convex part outer part

Claims (5)

A tread part that extends in the tire circumferential direction and is formed in an annular shape,
A pair of sidewall portions arranged on both sides of the tread portion,
A pair of bead portions arranged inside each tire radial direction of the pair of sidewall portions, and a pair of bead portions.
The bead core arranged in the bead portion and
A carcass layer spanning between the pair of bead portions,
Equipped with
The bead core is composed of at least one bead wire wound in the tire circumferential direction, and a plurality of layers in which a plurality of peripheral portions of the bead wire are aligned in the tire width direction and overlapped in the tire radial direction in a tire meridional cross section. Is forming
When the polygon formed by the common tangents of the plurality of peripheral portions of the bead wire in the tire meridional cross section is the outer shape of the bead core, the outer shape has a single apex on the outer side in the radial direction of the tire, and this apex is used as the outer shape. The internal angle between the two sides is an acute angle.
The carcass layer is folded back while bending along the peripheral edge of the bead core at the main body portion from the tread portion to the bead portion via the sidewall portion, and the tire radial outer end of the bead core. It consists of a folded portion extending from the position toward the sidewall portion while in contact with the main body portion.
In the entire range of 30% or more and 75% or less of the tire cross-sectional height from the reference position on the inner surface of the tire in the tire radial direction to the outside in the tire radial direction, the tire diameter protrudes from the tire inner surface. A ridge portion extending within a range in which the inclination angle in the tire circumferential direction with respect to the direction is 30 ° or more and 60 ° or less is formed.
The pneumatic tire is characterized in that the ridges are formed at intervals in a direction orthogonal to the extending direction of the ridges. The pneumatic tire according to claim 1 , wherein the convex portion has a height from the inner surface of the tire in the range of 2.0 mm or more and 4.0 mm or less. The pneumatic tire according to claim 1 or 2 , wherein the ridge portion has a width of 3.0 mm or more and 10.0 mm or less in a direction orthogonal to the extending direction of the ridge portion. The pneumatic tire according to any one of claims 1 to 3 , wherein the convex portions have a pitch between adjacent convex portions of 5 mm or more and 10 mm or less. The sidewall portion is an average side which is an average thickness of a portion located outside the carcass layer in the tire width direction in a range of 30% or more and 75% or less of the tire cross-sectional height outward from the reference position in the tire radial direction. The pneumatic tire according to any one of claims 1 to 4 , wherein the thickness is within the range of 1.0 mm or more and 2.5 mm or less.

Images