JP7124492B2 - pneumatic tire - Google Patents

Description

The present invention relates to pneumatic tires.

A pneumatic tire is attached to a rim and mounted on a vehicle with the inside filled with air. The internal air pressure receives the load when the vehicle is running. , it becomes difficult to bear the load. For this reason, in recent years, so-called run-flat tires have been proposed, which are capable of running even when the internal pressure is reduced due to a puncture or the like. As a run-flat tire, for example, side reinforcing rubber is arranged inside the sidewall portion to improve the bending rigidity of the sidewall portion, thereby suppressing deformation of the sidewall portion even when the internal pressure is low, and increasing the internal pressure. There is a type that enables run-flat running, which is running in a state where the air pressure is lowered.

Here, the temperature of a pneumatic tire rises due to continuous deformation due to load changes during vehicle running. Particularly, during run-flat running, a large stress is generated, so the temperature rises more easily. ing. Such a temperature rise tends to accelerate changes in the physical properties of the material over time, and also causes deterioration in durability. For this reason, some conventional pneumatic tires attempt to suppress the temperature rise. For example, the pneumatic tire described in Patent Document 1 is efficiently provided with a plurality of turbulence-generating ridges that extend in the tire radial direction and smoothly bend in one direction on the surface of the tire side portion. It is intended to cool the tire side portion.

WO2009/017167

However, the run-flat tire has a problem that the mass is increased because the side reinforcing rubber is disposed inside the sidewall portion. On the other hand, in recent years, as a technique for reducing the mass of a pneumatic tire, a technique for omitting the bead filler has been proposed. However, if the bead filler is omitted for the purpose of reducing the mass of the run-flat tire, the rigidity of the region from the bead to the sidewall decreases, which may reduce the durability during run-flat running. be. For this reason, it has been very difficult to achieve both reduction in mass and securing of durability.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic tire that can reduce the weight while suppressing deterioration in durability.

In order to solve the above-described problems and achieve the object, a pneumatic tire according to the present invention includes a tread portion extending in the tire circumferential direction and formed in an annular shape, and disposed on both sides of the tread portion in the tire width direction. a pair of tire side portions provided, a pair of bead portions disposed radially inward of each of the tire side portions, a bead core disposed in the bead portions, and between the pair of bead portions A carcass layer to be bridged over, a side reinforcing rubber disposed on the tire side portion, and a tire side formed on at least one of the tire side portions of the pair of tire side portions and being a surface of the tire side portion. and a plurality of protrusions protruding from the surface and extending along the tire side surface, and the bead core extends outward in the tire width direction from a portion where the width in the tire width direction is the maximum width. The carcass layer is formed to have a narrow width, and the carcass layer includes a carcass body portion that spans between the pair of bead portions, and a carcass body portion that is formed continuously from the carcass body portion and extends in the tire width direction of the bead core at the bead portion. and a folded portion that is folded back from the inside to the outside in the tire width direction, and the folded portion is folded back while being bent along the peripheral edge of the bead core to extend from the position of the outer end of the bead core in the tire radial direction to the carcass. Extending outward in the tire radial direction while being in contact with the main body, the convex portion has a maximum thickness of 1.5 mm or more and is positioned at a maximum height from the tire side surface. is in the range of 0.7 to 1.0 times the maximum thickness.

In the pneumatic tire, the distance in the tire radial direction from the tire radially outer end to the tire radially inner end of the convex portion is the maximum width of the tire from the tire radially inner end of the bead portion. It is preferably within the range of 0.2 times or more and 1.0 times or less of the height in the tire radial direction to the position.

In the pneumatic tire, the distance in the tire radial direction from the radially inner end of the bead portion to the position where the convex portion has the maximum thickness is the radially inner side of the bead portion. It is preferably arranged at a position within a range of 0.4 times or more and 1.2 times or less of the height in the tire radial direction from the end portion to the tire maximum width position.

In the pneumatic tire described above, the pneumatic tire is mounted on the vehicle so as to rotate in a specified rotational direction around a rotation axis when the vehicle moves forward, and the convex portion extends from the first-arrival side in the rotational direction. It is preferable to incline with respect to the tire circumferential direction in a direction from the inner side to the outer side in the tire radial direction toward the rear landing side.

In the above pneumatic tire, it is preferable that the convex portion has at least one bent portion, which is a position where the extending direction of the convex portion changes.

In the above pneumatic tire, the convex portion has a plurality of extension portions by being bent at the bent portion, and the plurality of extension portions is formed by a first extension portion and the above-mentioned a second extension portion that is the extension portion continuous from the first extension portion; and a third extension portion which is the extension portion continuous from the second extension portion via a bent portion, and the second extension portion extends in the tire radial direction with respect to the tire circumferential direction. It is preferable that the inclination is greater than that of the first extending portion and the third extending portion.

In the pneumatic tire described above, the length of the first extension portion is preferably longer than the length of the second extension portion and the third extension portion.

In the above pneumatic tire, it is preferable that the second extension portion has a maximum thickness greater than that of the first extension portion and the third extension portion.

In the above pneumatic tire, the bead core is composed of at least one bead wire wound in the tire circumferential direction, and in the tire meridional cross section, at least one row of a plurality of wound portions of the bead wire arranged in the tire width direction and the tire diameter A plurality of layers that overlap in the direction are formed, and among the plurality of layers, the width W0 of the layer that has the largest number of rows included, the width W1 of the innermost layer in the tire radial direction, and the outermost layer in the tire radial direction The width W2 of the layer satisfies the relationship of W1>W2 and W2≦(0.5×W0), and among the plurality of layers, the layer having the largest number of rows is the tire diameter of the bead core. It is preferably positioned radially inward of the center position of the tire.

In the above-described pneumatic tire, the bead core is defined as the inner side in the tire radial direction of the outer shape of the bead wire when a polygon formed by common tangents of a plurality of circumferential portions of the bead wire in the tire meridional cross section is the outer shape of the bead wire. The inner angles α and β of the corners located at both ends of the satisfy the relationships of α>90° and β>90°, and the peripheral length L0 of the outer shape and the inner side of the outer shape in the tire radial direction A length L1, a length L2 of an inclined side on the bead toe side connected to the inner side in the tire radial direction of the outer shape, and a length of an inclined side on the bead heel side connected to the inner side in the tire radial direction of the outer shape. L3 preferably satisfies the relationships of 0.25≦{(L1+L2)/L0}≦0.40 and 1.0≦{(L1+L2)/(2×L3)}≦2.5.

In the above pneumatic tire, it is preferable that the average diameter of the bead wire is within the range of 0.8 mm or more and 1.8 mm or less.

ADVANTAGE OF THE INVENTION The pneumatic tire which concerns on this invention is effective in the ability to reduce a mass, suppressing the deterioration of durability.

FIG. 1 is a tire meridional cross-sectional view showing a main part of a pneumatic tire according to Embodiment 1. FIG. 2 is a view taken along line AA in FIG. 1. FIG. FIG. 3 is a detailed view of the protrusion shown in FIG. 4 is a view taken along line BB in FIG. FIG. 5 is a detailed view of the bead core shown in FIG. 1; FIG. 6 is a plan view of essential parts showing a tire side surface of a pneumatic tire according to Embodiment 2. FIG. FIG. 7 is a plan view of essential parts showing a tire side surface of a pneumatic tire according to Embodiment 3. FIG. FIG. 8 is a plan view of essential parts showing a tire side surface of a pneumatic tire according to Embodiment 4. FIG. FIG. 9 is a detailed view of the C section in FIG. FIG. 10 is a modification of the pneumatic tire according to Embodiment 1, and is an explanatory diagram of a modification of the laminated structure of the bead wires. FIG. 11A is a chart showing the results of a performance evaluation test of pneumatic tires. FIG. 11B is a chart showing the results of a performance evaluation test for pneumatic tires. FIG. 11C is a chart showing the results of a performance evaluation test for pneumatic tires.

EMBODIMENT OF THE INVENTION Below, embodiment of the pneumatic tire which concerns on this invention is described in detail based on drawing. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be replaced and easily conceived by those skilled in the art, or those that are substantially the same.

[Embodiment 1]
In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, the tire radial direction inner side refers to the side facing the rotation axis in the tire radial direction, and the tire radial direction outer side. means the side away from the rotation axis in the tire radial direction. Moreover, the tire circumferential direction refers to the circumferential direction with the rotation axis as the central axis. In addition, the tire width direction refers to a direction parallel to the rotation axis, the tire width direction inner side refers to the side facing the tire equatorial plane (tire equator line) CL in the tire width direction, and the tire width direction outer side refers to the direction in the tire width direction. The side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane perpendicular to the rotation axis of the pneumatic tire 1 and passing through the center of the tire width of the pneumatic tire 1. The tire equatorial plane CL is the center of the pneumatic tire 1 in the tire width direction. The tire width direction centerline, which is the position, coincides with 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, excluding the protrusions 30 (see FIG. 1) described later, that is, the tire equatorial plane excluding the protrusions 30 in the tire width direction. It is the distance between the parts furthest from CL. A tire equator line is a line that is on the tire equatorial plane CL and extends along the tire circumferential direction of the pneumatic tire 1 . Further, in the following description, a meridional section of the tire refers to a section of the tire cut along a plane including the tire rotation axis.

FIG. 1 is a tire meridional cross-sectional view showing a main part of a pneumatic tire 1 according to Embodiment 1. FIG. For the pneumatic tire 1 shown in FIG. 1, the mounting direction with respect to the vehicle, that is, the direction at the time of mounting on the vehicle, is specified. That is, when the pneumatic tire 1 shown in FIG. 1 is mounted on a vehicle, the side facing the inside of the vehicle is the inside in the vehicle mounting direction, and the side facing the outside of the vehicle is the outside in the vehicle mounting direction. The specification of the vehicle mounting direction inner side and the vehicle mounting direction outer side is not limited to the case of mounting to the vehicle. For example, when assembled on the rim, the orientation of the rim with respect to the inner side and the outer side of the vehicle in the tire width direction is determined. The orientation for the outside of the mounting direction is specified. In addition, the pneumatic tire 1 has a mounting direction indicator (not shown) that indicates the mounting direction with respect to the vehicle. The mounting direction display portion is configured by, for example, a mark or unevenness provided on the sidewall portion 4 of the tire. For example, ECER30 (Economic Commission Regulations for Europe, Article 30) obliges the mounting direction indicator to be provided on the sidewall portion 4, which is located on the outside in the vehicle mounting direction when the tire is mounted on the vehicle. Moreover, the pneumatic tire 1 according to the first embodiment is a pneumatic tire 1 mainly used for passenger cars.

A pneumatic tire 1 according to Embodiment 1 has a tread portion 2 , shoulder portions 3 on both sides of the tread portion, and sidewall portions 4 and bead portions 5 that are successively continuous from each shoulder portion 3 . The pneumatic tire 1 also includes a carcass layer 6 , a belt layer 7 , a belt reinforcing layer 8 and an inner liner 9 .

The tread portion 2 is formed in an annular shape extending in the tire circumferential direction at the outermost portion in the tire radial direction when viewed in the tire meridional cross section, and is the outermost portion of the pneumatic tire 1 in the tire radial direction. , and its outer peripheral surface forms the contour of the pneumatic tire 1 . The outer peripheral surface of the tread portion 2 is formed as a ground-contacting surface 10, which is a surface that can come into contact with the road surface mainly during running. A plurality of grooves such as the groove 17 are formed. The tread portion 2 also has a tread rubber 18 that is a rubber composition. The tread rubber 18 may be formed by laminating a plurality of rubber compositions having different physical properties in the tire radial direction.

The shoulder portions 3 are portions on both outer sides of the tread portion 2 in the tire width direction. Moreover, the sidewall portions 4 are positioned inside the shoulder portion 3 in the tire radial direction, and a pair of sidewall portions 4 are arranged on both sides in the tire width direction. That is, the pair of sidewall portions 4 are arranged on both sides of the tread portion 2 in the tire width direction. ing. The sidewall portion 4 formed in this manner is curved in a direction convex outward in the tire width direction when viewed in a tire meridional cross section, and is exposed at the outermost portion of the pneumatic tire 1 in the tire width direction. It's part.

In addition, the bead portions 5 are arranged inside each of the pair of sidewall portions 4 in the tire radial direction. It is Each bead portion 5 also has a bead core 11 . The bead core 11 is formed by winding a bead wire, which is a steel wire, into a ring shape.

The sidewall portion 4 and the bead portion 5 are included in tire side portions 20 located on both sides in the tire width direction. In the first embodiment, the tire side portion 20 is a region between the radially inner position of the tread rubber 18 and the bead heel 5b, which is the outer end portion of the inner peripheral surface of the bead portion 5 in the tire width direction. Say. That is, a pair of tire side portions 20 are arranged on both sides of the tread portion 2 in the tire width direction, and a pair of bead portions 5 are arranged on the inside of each tire side portion 20 in the tire radial direction.

The carcass layer 6 is folded back from the tire width direction inner side to the tire width direction outer side by a pair of bead cores 11 at each end in the tire width direction, and is wound around in a toroidal shape in the tire circumferential direction to form a tire skeleton. It is. The carcass layer 6 is formed by coating a plurality of carcass cords (not shown) arranged side by side with a certain angle in the tire circumferential direction along the tire meridian direction with respect to the tire circumferential direction. Carcass cords are made of, for example, organic fibers such as polyester, rayon, and nylon. At least one carcass layer 6 is provided.

Specifically, the carcass layer 6 is arranged from one bead portion 5 to the other bead portion 5 of a pair of bead portions 5 located on both sides in the tire width direction, and near both ends of the carcass layer 6 , is wound outward in the tire width direction along the bead core 11 at the bead portion 5 so as to wrap the bead core 11 . For this reason, the carcass layer 6 includes a carcass body portion 6a that spans between the pair of bead portions 5, and an outer end of the bead core 11 in the tire radial direction that is bent and folded back along the periphery of the bead core 11 at the bead portion 5. and a folded portion 6b extending outward in the tire radial direction while contacting the carcass main body portion 6a from the position of the portion. Among these, the folded portion 6b is formed continuously from the carcass main body portion 6a, and at a position where the bead core 11 is arranged in the bead portion 5, the folded portion 6b is folded from the inner side in the tire width direction along the peripheral edge of the bead core 11 to the outer side in the tire width direction. is folded over.

The belt layer 7 has a multi-layered structure in which at least two layers of belts 7a and 7b are laminated, is arranged outside in the tire radial direction which is the outer circumference of the carcass layer 6 in the tread portion 2, and covers the carcass layer 6 in the tire circumferential direction. is. The belts 7a and 7b are formed by coating a plurality of cords (not shown) arranged side by side at a predetermined angle (for example, 20° to 30°) with respect to the tire circumferential direction with a coating rubber. The cord is made of, for example, steel or an organic fiber such as polyester, rayon, or nylon. The overlapping belts 7a and 7b are arranged so that their cords intersect each other.

The belt reinforcing layer 8 is arranged outside in the tire radial direction, which is the outer circumference of the belt layer 7, and covers the belt layer 7 in the tire circumferential direction. The belt reinforcing layer 8 is formed by coating a plurality of cords (not shown) arranged side by side in the tire width direction substantially parallel to the tire circumferential direction with a coat rubber. The cord is made of, for example, steel or organic fibers such as polyester, rayon, or nylon, and the angle of the cord is within a range of ±5° with respect to the tire circumferential direction. In the first embodiment, the belt reinforcing layer 8 includes a belt cover 8a disposed so as to cover the entirety of the belt layer 7 in the tire width direction, and a belt cover 8a disposed outside the belt cover 8a in the tire radial direction of the belt layer 7 in the tire width direction. Two layers are laminated with the edge cover 8b disposed only near the end. The belt reinforcing layer 8 may have other structures, such as a belt cover 8a that covers the entire belt layer 7, or an edge cover that covers the end of the belt layer 7 in the width direction of the tire. 8b only. The belt reinforcing layer 8 may be arranged so as to overlap at least the end portion in the tire width direction of the belt layer 7 . The belt reinforcing layer 8 configured as described above is provided by winding a belt-shaped strip material having a width of about 10 mm, for example, in the tire circumferential direction.

The inner liner 9 is arranged along the carcass layer 6 on the inner side of the carcass layer 6 or on the inner side of the carcass layer 6 in the pneumatic tire 1 . The inner liner 9 is an air permeation prevention layer that is arranged on the inner cavity surface of the tire and covers the carcass layer 6, suppresses oxidation due to the exposure of the carcass layer 6, and prevents the air filled in the tire from leaking. The inner liner 9 is made of, for example, a rubber composition containing butyl rubber as a main component, a thermoplastic resin, or a thermoplastic elastomer composition obtained by blending an elastomer component into a thermoplastic resin. In addition, the inner liner 9 is adhered to the carcass layer 6 via a tie rubber (not shown), and forms the tire inner surface, which is the inner surface of the pneumatic tire 1 .

Further, a side reinforcing rubber 25 is arranged on the tire side portion 20 . The side reinforcing rubber 25 is a rubber member provided inside the tire side portion 20, and is arranged without being exposed on the tire inner surface or the tire outer surface. Specifically, the side reinforcing rubber 25 is mainly located inside the tire side portion 20 of the carcass layer 6 in the tire width direction, and is between the carcass layer 6 and the inner liner 9 in the tire side portion 20 . It is arranged, and the shape in the tire meridional cross section is formed into a crescent shape that protrudes outward in the tire width direction.

The side reinforcing rubber 25 formed in a crescent shape has an outer end in the tire radial direction located radially inward of the belt layer 7 in the tread portion 2, and the side reinforcing rubber 25 and the belt layer 7 are They are arranged so that they are partly overlapped in the tire radial direction with a wrap amount within a predetermined range. The side reinforcing rubber 25 arranged in this way is made of a rubber material having a higher strength than the side rubber 4 a forming the sidewall portion 4 and the rim cushion rubber 19 arranged on the bead portion 5 . Specifically, the rubber hardness indicated by JIS-A hardness conforming to JIS K6253 is such that the rubber hardness of the side reinforcing rubber 25 is higher than the rubber hardness of the side rubber 4a and the rim cushion rubber 19. . The rubber hardness of the side reinforcing rubber 25 is, for example, within the range of 65 or more and 85 or less.

In addition, the side reinforcing rubber 25 has a modulus of 5.0 MPa or more and 12.0 MPa or less at 100% elongation. The modulus at 100% elongation in this case is measured by a tensile test at 23° C. in accordance with JIS K6251 (using No. 3 dumbbells), and indicates the tensile stress at 100% elongation. The pneumatic tire 1 according to the first embodiment is provided with the side reinforcing rubber 25 having a relatively high strength in the tire side portion 20 as described above, so that the tire can run even when the internal pressure is lowered due to a puncture or the like. It is configured as a so-called run-flat tire.

Further, in the pneumatic tire 1 according to Embodiment 1, a plurality of protrusions 30 are formed on the tire side surface 21 that is the surface of the tire side portion 20 . The plurality of protrusions 30 are formed so as to protrude from the tire side surface 21 and extend along the tire side surface 21 . The convex portion 30 is formed on the tire side portion 20 on the outer side in the vehicle mounting direction among the tire side portions 20 positioned on both sides in the tire width direction. The convex portion 30 is a convex portion that protrudes from the reference plane of the tire side surface 21 excluding patterns, characters, unevenness, and the like.

The plurality of protrusions 30 are formed straddling the tire maximum width position W on the tire side surface 21 in the tire radial direction. The maximum tire width position W protrudes from the tire side surface 21 when the pneumatic tire 1 is mounted on a regular rim, filled with regular internal pressure, and in a no-load state in which no load is applied to the pneumatic tire 1. This is the position in the tire radial direction at which the size in the tire width direction is the maximum, excluding structures such as patterns and characters. In the case of a tire equipped with a rim protect bar (which is provided along the tire circumferential direction and protrudes outward in the tire width direction) to protect the rim, the position of the rim protect bar is determined by the dimension in the tire width direction. Although it is the maximum position, the maximum tire width position W defined in the first embodiment excludes the rim protect bar.

The regular rim referred to here is a "standard rim" defined by JATMA, a "design rim" defined by TRA, or a "measuring rim" defined by ETRTO. The normal internal pressure is the maximum air pressure specified by JATMA, the maximum value specified by TRA "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", or the "INFLATION PRESSURES" specified by ETRTO.

The convex portion 30 formed straddling the tire maximum width position W in the tire radial direction has a distance Lc in the tire radial direction between both end portions 31 in the tire radial direction of the bead portion 5 from the radially inner end portion of the tire. It is in the range of 0.2 times or more and 1.0 times or less of the height H in the tire radial direction up to the maximum width position W. In this case, the inner end portion of the bead portion 5 in the tire radial direction is a bead toe 5a of the bead portion 5 . That is, the inner peripheral surface of the bead portion 5 extends from the tire radially inner side toward the tire radially outer side from the bead toe 5a side, which is the tire width direction inner end portion, toward the tire width direction outer end portion, the bead heel 5b side. , the radially inner end of the bead portion 5 is located at the bead toe 5a.

In addition, the distance Lc in the tire radial direction between both end portions 31 of the convex portion 30 in the tire radial direction is the inner end portion in the tire radial direction from the outer end portion 31o which is the outer end portion in the tire radial direction of the convex portion 30. It is a distance Lc in the tire radial direction to a certain inner end portion 31i. That is, the distance Lc in the tire radial direction between both end portions 31 of the convex portion 30 in the tire radial direction is, in other words, the length Lc of the convex portion 30 in the tire radial direction.

The distance Lc in the tire radial direction between both end portions 31 of the convex portion 30 in the tire radial direction is 0.2 to 0.9 times the height H in the tire radial direction from the bead toe 5a to the tire maximum width position W. It is preferably within the following range.

2 is a view taken along line AA in FIG. 1. FIG. A plurality of protrusions 30 formed on the tire side surface 21 of the tire side portion 20 are formed to extend along the tire radial direction. In addition, the plurality of protrusions 30 have substantially the same shape and are arranged discontinuously at equal intervals in the tire circumferential direction, and the positions in the tire radial direction of the plurality of protrusions 30 are also arranged at substantially the same positions. It is The plurality of protrusions 30 are thus arranged at equal intervals in the tire circumferential direction, and each protrusion 30 is formed extending along the tire radial direction, so that the plurality of protrusions 30 are formed around the tire rotation axis. are provided radially.

FIG. 3 is a detailed view of the convex portion 30 shown in FIG. The height Hc of the protrusion 30 from the tire side surface 21 varies depending on the position in the extending direction of the protrusion 30, that is, the position of the protrusion 30 in the tire radial direction. Specifically, the convex portion 30 has two height changing portions 32 formed between the outer end portion 31o and the inner end portion 31i so that the height Hc from the tire side surface 21 varies. . Of these, the height Hc from the tire side surface 21 increases from the outer end 31o toward the height changing portion 32 in the portion between the height changing portion 32 near the outer end 31o and the outer end 31o. Is high. Similarly, the portion between the height change portion 32 near the inner end portion 31i and the inner end portion 31i also has a height Hc from the tire side surface 21 as it goes from the inner end portion 31i toward the height change portion 32. Is high.

On the other hand, in the portion between the two height changing portions 32, the change in height Hc from the tire side surface 21 is small, and the height Hc from the tire side surface 21 is substantially constant. Since the height Hc of the convex portion 30 from the tire side surface 21 increases toward the height change portion 32 from the outer end portion 31o or the inner end portion 31i, the height Hc from the tire side surface 21 increases. , the height at the portion located between the two height changing portions 32 is the highest. Further, since the height Hc from the tire side surface 21 is substantially constant in the portion between the two height change portions 32 of the protrusion 30, the height Hc between the two height change portions 32 is substantially constant. The portion in between is formed as a maximum height region 33 .

4 is a view taken along line BB in FIG. The thickness Tc of the convex portion 30 also changes depending on the position in the extending direction of the convex portion 30 . Specifically, the convex portion 30 has two thickness changing portions 34 between the outer end portion 31o and the inner end portion 31i where the degree of change in the thickness Tc is changed. The two thickness change portions 34 are located at the same positions as the two height change portions 32 in the extending direction of the convex portion 30 . That is, the thickness change portion 34 closer to the outer end portion 31o and the height change portion 32 closer to the outer end portion 31o are positioned at the same position in the extending direction of the convex portion 30, and the inner end portion 31i The thickness change portion 34 on the side and the height change portion 32 on the side of the inner end portion 31i are positioned at the same position in the extending direction of the convex portion 30 .

In addition, the portion between the thickness change portion 34 near the outer end portion 31o and the outer end portion 31o of the convex portion 30 has a thickness Tc that increases toward the thickness change portion 34 from the outer end portion 31o. ing. Similarly, the portion between the thickness change portion 34 near the inner end portion 31i and the inner end portion 31i also has a thickness Tc that increases toward the thickness change portion 34 from the inner end portion 31i.

On the other hand, in the portion between the two thickness changing portions 34, the thickness Tc varies little, and the thickness Tc of the convex portion 30 is substantially constant. Since the thickness Tc of the convex portion 30 increases from the outer end portion 31o and the inner end portion 31i toward the thickness changing portion 34, the thickness Tc of the convex portion 30 is equal to that of the two thickness changing portions. The thickness at the portion located between 34 is the thickest. In addition, since the thickness Tc of the convex portion 30 between the two thickness changing portions 34 is substantially constant, the portion between the two thickness changing portions 34 has a maximum It is formed as a thickness region 35 . The convex portion 30 has the thickest thickness Tc at the portion located in the maximum thickness region 35, and the thickness Tc at the portion located in the maximum thickness region 35 is within the range of 1.5 mm or more and 10 mm or less. It has become. That is, the convex portion 30 has a maximum thickness within a range of 1.5 mm or more and 10 mm or less.

In addition, the convex portion 30 has a distance Hm (see FIG. ) is in the range of 0.4 to 1.2 times the height H in the tire radial direction from the bead toe 5a to the tire maximum width position W (see FIG. 1). The convex portion 30 has the thickest thickness Tc at the portion located in the maximum thickness region 35 , and the maximum thickness region 35 has a predetermined length in the extending direction of the convex portion 30 . Therefore, in the first embodiment, the maximum thickness position 36 is the center position of the maximum thickness region 35 in the extending direction of the projection 30 . Further, the distance Hm in the tire radial direction from the bead toe 5a to the maximum thickness position 36 of the convex portion 30 is 0.7 times or more the height H in the tire radial direction from the bead toe 5a to the tire maximum width position W, and 1.0. It is preferably within the range of twice or less.

In addition, the maximum thickness region 35 of the convex portion 30 is defined by two thickness changing portions 34 on both end sides in the extending direction of the convex portion 30. The thickness changing portion 34 is the maximum height region 33 (see FIG. 3) are located at the same position in the extending direction of the convex portion 30 as the two height changing portions 32 . As a result, the maximum thickness region 35 and the maximum height region 33 are positioned at the same position in the extending direction of the projection 30 . Therefore, the convex portion 30 has a substantially maximum thickness at a position where the height Hc from the tire side surface 21 is the maximum height.

More specifically, the maximum height region 33 (see FIG. 3) where the height Hc from the tire side surface 21 is the maximum height is formed with a predetermined length in the extending direction of the convex portion 30. The convex portion 30 has a thickness Tc (see FIG. 4) at a position where the height from the tire side surface 21 is the maximum height, and is 0.7 to 1.0 times the maximum thickness of the convex portion 30. is within range. That is, the maximum height region 33 (see FIG. 3) and the maximum thickness region 35 (see FIG. 4) at the same position in the extending direction of the projection 30 have a thickness Tc equal to the maximum thickness region 35 (see FIG. 4). It is in the range of 0.7 to 1.0 times the thickness Tc at the height position 36 (see FIG. 4). As a result, the thickness Tc of the portion of the convex portion 30 located in the maximum height region 33 is approximately the maximum thickness.

FIG. 5 is a detailed view of the bead core 11 shown in FIG. The bead core 11 is composed of at least one bead wire 12 wound in the tire circumferential direction, and a plurality of winding portions of the bead wire 12 form at least one row arranged in the tire width direction and a plurality of layers overlapping in the tire radial direction. ing. Note that the bead core 11 may have a so-called single-wound structure in which a single bead wire 12 is continuously wound as long as a plurality of winding portions of the bead wire 12 form rows and layers in the meridional cross section of the tire. It may be a so-called layer winding structure in which a plurality of bead wires 12 are wound in an aligned state.

The bead wire 12 forming the bead core 11 by being wound in the tire circumferential direction in this way has an average diameter within the range of 0.8 mm or more and 1.8 mm or less. The average diameter of the bead wire 12 is preferably in the range of 1.0 mm or more and 1.6 mm or less, and more preferably in the range of 1.1 mm or more and 1.5 mm or less. In addition, the total area of the bead wires 12 (sum of the cross-sectional areas of the winding portions of the bead wires 12 included in the tire meridional cross section of each bead core 11) is preferably in the range of 10 mm ² or more and 50 mm ² or less, and 15 mm ² or more and 48 mm. It is more preferably in the range of ² or less, and even more preferably in the range of 20 mm ² or more and 45 mm ² or less.

In the first embodiment, the bead core 11 has a layer including three rows of winding portions, a layer including four rows of winding portions, a layer including three rows of winding portions, and two rows of winding portions in order from the innermost side in the tire radial direction. It has a structure in which a total of five layers, a layer including a layer including a line of winding portions, are laminated. In the following description, this structure will be referred to as "3+4+3+2+1 structure". Similarly, in the following description, the laminated structure of the bead wire 12 will be expressed in a similar format in which the number of rows included in each layer is connected with "+" in order from the innermost layer in the tire radial direction. Furthermore, in the first embodiment, the bead core 11 is formed by laminating the bead wires 12 in a bale-like manner. The “bales stacking” is a stacking method in which the centers of the three winding portions that are in contact with each other form a substantially equilateral triangle, and is a stacking structure with a high packing rate, sometimes called a hexagonal packing arrangement.

The bead core 11 formed in this manner has a width W0 of the layer having the largest number of rows included among the plurality of layers, a width W1 of the innermost layer in the tire radial direction, and a width W1 of the innermost layer in the tire radial direction. The layer width W2 satisfies the relationship of W1>W2 and W2≦(0.5×W0). In this case, the widths W0, W1, and W2 are lengths along the tire width direction between the outer ends in the tire width direction of the circumferential portions on both sides in the tire width direction of each layer.

In addition, among the plurality of layers that the bead core 11 has, the layer having the largest number of rows included, that is, the layer having the largest width in the tire width direction has a tire diameter greater than the center position of the bead core 11 in the tire radial direction. direction inside. In other words, in the bead core 11, the portion where the width in the tire width direction is the maximum is located radially inward of the center position in the tire radial direction. The width in the tire width direction is narrowed. In other words, the bead core 11 tapers outward in the tire radial direction from the portion where the width in the tire width direction is the maximum so that the width in the tire width direction is smaller than the width W1 of the innermost layer in the tire radial direction. It is formed in a shape that In the following description, such a shape of the bead core 11 may be referred to as an "outer diameter side wedge shape".

In addition, when a polygon formed by common tangents of a plurality of circumferential portions of the bead wire 12 in the tire meridional cross section is defined as the outer shape 13 of the bead wire 12, the bead core 11 is formed at both ends of the tire radially inner sides of the outer shape 13 of the bead wire 12. The internal angles α and β of the located corners satisfy the relationships of α>90° and β>90°. The internal angles α and β of the corners located at both ends of the inner side in the tire radial direction of the contour shape 13 preferably satisfy the relationships of 100°≦α≦150° and 100°≦β≦150°. . In addition, in the first embodiment, the bead core 11 has a 3+4+3+2+1 laminated structure of the bead wires 12, so that the outer shell shape 13 has a substantially pentagonal shape.

In addition, the bead core 11 has a peripheral length L0 of the outer shape 13, a length L1 of the inner side in the tire radial direction of the outer shape 13, and an inclined side on the side of the bead toe 5a connected to the inner side in the tire radial direction of the outer shape 13. satisfies the relationship 0.25≤{(L1+L2)/L0}≤0.40. Further, in the bead core 11, the length L1, the length L2, and the length L3 of the inclined side of the bead heel 5b connected to the inner side of the outer contour 13 in the tire radial direction are 1.0≤{( L1+L2)/(2×L3)}≦2.5.

It should be noted that the length L2 in this case is located on the inner side in the tire width direction of the inner side in the tire radial direction among the plurality of sides forming the outer contour 13, and is the inner side in the tire width direction of the inner side in the tire radial direction. is the length of the side connected to the end of the Further, the length L3 is positioned outside the tire radial direction inner side in the tire width direction among the plurality of sides forming the outer shell shape 13, and is positioned at the tire width direction outer end of the tire radial direction inner side. is the length of the side connected to In addition, the circumferential length L0, the length L1, and the length L2 preferably satisfy the relationship of 0.28≦{(L1+L2)/L0}≦0.36, and the length L1 and the length L2 , the length L3 preferably satisfies the relationship 1.1≦{(L1+L2)/(2×L3)}≦2.0.

In addition, the length L2 of the inclined side of the bead toe 5a connected to the inner side in the tire radial direction of the outer shell shape 13 is preferably in the range of 1.5 mm or more and 8 mm or less, and is in the range of 2 mm or more and 5 mm or less. It is more preferable to have In addition, the length L1 of the inner side in the tire radial direction of the contour shape 13 is preferably in the range of 2 mm or more and 10 mm or less, and more preferably 2.5 mm or more and 7 mm or less.

In the bead portion 5, the carcass layer 6 is bent and folded back along the periphery of the bead core 11. Since the bead core 11 is formed in a wedge shape on the outer diameter side, the carcass layer 6 is formed in the shape of the bead core 11 in the meridional cross section of the tire. It bends along the outer diameter side wedge shape that is the shape. That is, since the bead core 11 has a substantially pentagonal shape in the meridional cross-section of the tire, the carcass layer 6 extending along the periphery of the bead core 11 also extends while bending in a substantially pentagonal shape. Furthermore, the portion of the folded portion 6 b of the carcass layer 6 that is located outside the tire radial direction outer end of the bead core 11 in the tire radial direction is in contact with the carcass body portion 6 a of the carcass layer 6 , and the carcass body portion 6 a of the carcass layer 6 is , extending radially outward of the tire. Therefore, in the bead portion 5 , a closed region surrounding the bead core 11 is formed by the carcass body portion 6 a and the folded portion 6 b of the carcass layer 6 .

In the closed region formed by the carcass body portion 6a and the turn-up portion 6b of the carcass layer 6, substantially only the bead cores 11 are present. For this reason, the pneumatic tire 1 according to the first embodiment includes a bead filler used in a conventional pneumatic tire or a similar tire constituent member (located radially outside the bead core 11 in the tire radial direction to form the carcass layer 6). A member wrapped by the carcass main body 6a and the folded-back portion 6b to increase the rigidity from the bead portion 5 to the sidewall portion 4) is not arranged. That is, in the pneumatic tire 1, the closed region includes the insulation rubber covering the bead wire 12 and the rubber filling the slight gap formed between the bead core 11 and the carcass layer 6. A bead filler having a large volume such as that of a pneumatic tire is not used. In the pneumatic tire 1 according to the first embodiment, the ratio 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 (a/A × 100%) is defined as rubber occupancy of the closed region. As a percentage, the rubber occupancy is in the range of 0.1% or more and 15% or less.

When the pneumatic tire 1 according to the first embodiment is mounted on a vehicle, the pneumatic tire 1 is fitted to the rim wheel by fitting the rim wheel to the bead portion 5, and the inside is filled with air. Attached to the vehicle in an inflated state. At that time, the pneumatic tire 1 according to Embodiment 1 is mounted on the vehicle in the designated direction because the mounting direction with respect to the vehicle is specified. That is, it is mounted on the vehicle in the direction designated by the mounting direction indicator attached to the sidewall portion 4 . Specifically, among the tire side portions 20 positioned on both sides in the tire width direction, the tire side portion 20 on the side where the convex portion 30 is formed is mounted on the vehicle so as to be positioned on the outside in the vehicle mounting direction.

When the vehicle equipped with the pneumatic tire 1 runs, the pneumatic tire 1 rotates while the portion of the ground contact surface 10 located below and facing the road surface is in contact with the road surface. The vehicle travels by transmitting driving force and braking force to the road surface and generating turning force by the frictional force between the ground contact surface 10 and the road surface. For example, when a vehicle equipped with the pneumatic tire 1 travels on a dry road surface, the frictional force between the ground contact surface 10 and the road surface mainly causes the driving force and the braking force to be transmitted to the road surface, as well as the turning force. It runs by generating In addition, when traveling on a wet road surface, water between the ground contact surface 10 and the road surface enters grooves such as the circumferential grooves 16 and the lug grooves 17 formed in the contact surface 10, and contacts with these grooves. It travels while draining water between the ground 10 and the road surface. As a result, the ground contact surface 10 can easily contact the road surface, and the frictional force between the ground contact surface 10 and the road surface enables the vehicle to run as desired.

When the vehicle equipped with the pneumatic tire 1 is running, the frictional force generated between the ground contact surface 10 of the pneumatic tire 1 and the road surface enables the vehicle to run. During running, loads in various directions act on each part of the pneumatic tire 1 . The load acting on the pneumatic tire 1 is received by the pressure of the air filled inside, the carcass layer 6 provided as the skeleton of the pneumatic tire 1, and the like. For example, the load acting in the tire radial direction between the tread portion 2 and the bead portion 5 due to the weight of the vehicle and the unevenness of the road surface is mainly received by the pressure of the air filled inside the pneumatic tire 1. , the sidewall portion 4 and the like are bent. That is, the air filled inside the pneumatic tire 1 acts as a force that pushes the pneumatic tire 1 outward from the inside. When the vehicle is running, the pneumatic tire 1 receives a large load due to the urging force from the inside to the outside due to the air filled inside, and the sidewall portion 4 and the like flex appropriately. By running, the vehicle can run while ensuring ride comfort.

Here, the air inside the pneumatic tire 1 may leak due to, for example, a puncture caused by a foreign object stuck in the ground contact surface 10 . When the internal air leaks, the air pressure decreases, and the biasing force of the air from the inside of the pneumatic tire 1 to the outside is reduced, so it becomes difficult for the internal air pressure to receive the load during running of the vehicle. . In this case, the pneumatic tire 1 according to Embodiment 1 can receive part of the load that is difficult to receive due to the air pressure by the side reinforcing rubber 25 provided in the tire side portion 20. . That is, since the side reinforcing rubber 25 is made of a rubber material having a higher strength than the side rubber 4a forming the sidewall portion 4, a large load in the tire radial direction is exerted on the tire side portion 20 such as the sidewall portion 4. The side reinforcing rubber 25 is capable of suppressing deformation of the tire side portion 20 in the tire radial direction even when the force acts on the side reinforcing rubber 25 .

On the other hand, when the tire side portion 20 is provided with the side reinforcing rubber 25, the mass of the tire side portion 20 increases, and accordingly the mass of the pneumatic tire 1 as a whole increases. When the mass of the pneumatic tire 1 becomes large, adverse effects such as deterioration of ride comfort during vehicle running and deterioration of fuel consumption are likely to occur. Therefore, in the pneumatic tire 1 according to the first embodiment, the bead filler is not arranged in the bead portion 5 and the bead filler is omitted, thereby reducing the mass of the pneumatic tire 1 while providing the side reinforcing rubber 25. I am planning. As a result, deterioration in performance due to an increase in the mass of the pneumatic tire 1 is suppressed.

However, if the bead filler is omitted, the rigidity of the tire side portion 20 in the vicinity of the bead portion 5 is lowered, so the steering stability is likely to be lowered. In addition, since the rigidity near the bead portion 5 is reduced, there is a risk that the load on the side reinforcing rubber 25 will become too large during so-called run-flat running, which is a state in which the internal pressure is reduced. There is a possibility that failures may easily occur in the surrounding members. Therefore, there is a possibility that the durability during run-flat running is likely to deteriorate.

On the other hand, in the pneumatic tire 1 according to Embodiment 1, the tire side portion 20 is provided with the convex portion 30 protruding from the tire side surface 21 . As a result, the reduction in rigidity in the vicinity of the bead portion 5 due to the omission of the bead filler can be compensated for by the convex portion 30, so that the rigidity of the tire side portion 20 can be ensured and the reduction in steering stability can be prevented. can be suppressed. Further, since the rigidity of the tire side portion 20 can be ensured by providing the tire side portion 20 with the convex portion 30, the load on the side reinforcing rubber 25 during run-flat running can be reduced. It is possible to suppress deterioration in durability over time.

Furthermore, since the convex portion 30 has a maximum thickness of 1.5 mm or more, the rigidity of the tire side portion 20 can be ensured more reliably. That is, if the maximum thickness of the projection 30 is less than 1.5 mm, the maximum thickness of the projection 30 is too thin, and it becomes difficult to ensure the rigidity of the projection 30 itself. There is a possibility that it may become difficult to ensure the rigidity of the In this case, it may be difficult to suppress deterioration in steering stability or to suppress deterioration in durability during run-flat running. On the other hand, when the maximum thickness of the convex portion 30 is 1.5 mm or more, the rigidity of the tire side portion 20 can be ensured more reliably, and a decrease in steering stability can be suppressed. It is possible to suppress deterioration in durability during running.

In addition, since the thickness Tc of the convex portion 30 at the position where the height Hc from the tire side surface 21 is the maximum height is within the range of 0.7 times or more and 1.0 times or less of the maximum thickness, Rigidity can be effectively secured at positions where rigidity can be easily secured in the convex portion 30 . That is, the vicinity of the position where the height Hc of the convex portion 30 is the maximum height is the position where the volume per unit length in the extending direction of the convex portion 30 is large, and the position where the rigidity of the convex portion 30 can be easily secured. However, if the thickness Tc at this position is less than 0.7 times the maximum thickness, it may be difficult to effectively secure the rigidity near the position where the height Hc is the maximum height.

On the other hand, when the thickness Tc of the convex portion 30 at the position where the height Hc is the maximum height is within the range of 0.7 times or more and 1.0 times or less of the maximum thickness, the convex portion 30 It is possible to effectively ensure the rigidity at the position where the rigidity can be easily ensured. As a result, the rigidity of the tire side portion 20 can be ensured more reliably, and a decrease in steering stability can be suppressed, and a decrease in durability during run-flat running can be suppressed. As a result of these, it is possible to reduce the mass while suppressing deterioration in durability.

Further, in the convex portion 30, the distance Lc in the tire radial direction from the outer end portion 31o to the inner end portion 31i is 0.2 times or more the height H in the tire radial direction from the bead toe 5a to the maximum width position W of the tire. Since it is within the range of 0.0 times or less, it is possible to prevent the mass of the convex portion 30 from becoming too large while ensuring the heat dissipation of the convex portion 30 by ensuring the surface area of the convex portion 30 . That is, when the distance Lc from the outer end 31o to the inner end 31i of the protrusion 30 is less than 0.2 times the height H from the bead toe 5a to the maximum tire width position W, both ends of the protrusion 30 Since the distance Lc between the portions 31 in the tire radial direction is too short, the surface area of the convex portion 30 may become too small. In this case, since the heat dissipation performance of the convex portion 30 is lowered, it may become difficult to ensure the durability. Here, the relationship between the heat dissipation and durability of the convex portion 30 will be explained. During run-flat running, the tire side portion 20 flexes more than during running with the normal internal pressure. , the tire side portion 20 tends to generate heat. Rubber members such as the side rubber 4a and the side reinforcing rubber 25 that constitute the tire side portion 20 are likely to break when the temperature rises. tend to deteriorate.

On the other hand, since the convex portion 30 is formed to protrude from the tire side surface 21, the surface area of the tire side surface 21 can be substantially increased. It is possible to dissipate heat from As a result, it is possible to suppress the temperature of the members constituting the tire side portion 20 from becoming too high, and it is possible to suppress the susceptibility to breakage due to an increase in temperature. It becomes easier to ensure the reliability. However, if the surface area of the convex portion 30 becomes too small because the distance Lc between the end portions 31 of the convex portion 30 in the tire radial direction is too short, the heat generated by the tire side portion 20 is transferred to the convex portion 30. It may be difficult to effectively dissipate heat from the In this case, it becomes difficult to prevent the temperature of the members forming the tire side portion 20 from becoming too high, and thus it may become difficult to ensure the durability of the tire side portion 20 .

Further, when the distance Lc from the outer end 31o to the inner end 31i of the protrusion 30 is greater than 1.0 times the height H from the bead toe 5a to the maximum tire width position W, both ends of the protrusion 30 Since the distance Lc between the protrusions 31 in the tire radial direction is too long, the mass of the protrusions 30 may become too large. In this case, even if the mass of the pneumatic tire 1 is reduced by omitting the bead filler, the mass of the protrusions 30 increases, so there is a possibility that it will be difficult to reduce the mass of the pneumatic tire 1 .

On the other hand, the distance Lc from the outer end 31o to the inner end 31i of the convex portion 30 is within the range of 0.2 times or more and 1.0 times or less of the height H from the bead toe 5a to the tire maximum width position W. , it is possible to prevent the mass of the protrusions 30 from becoming too large while securing the heat dissipation performance of the protrusions 30 by ensuring the surface area of the protrusions 30 . As a result, it is possible to more reliably prevent the temperature of the members forming the tire side portion 20 from becoming too high, and to ensure the durability of the tire side portion 20 more reliably. As a result, it is possible to reduce the mass while suppressing deterioration in durability more reliably.

In addition, the distance Hm in the tire radial direction from the bead toe 5a to the maximum thickness position 36 of the convex portion 30 is at least 0.4 times the height H in the tire radial direction from the bead toe 5a to the tire maximum width position W1. Since it is arranged at a position within the range of twice or less, the rigidity of the tire side portion 20 can be more effectively secured. That is, when the distance Hm in the tire radial direction from the bead toe 5a to the maximum thickness position 36 is less than 0.4 times the height H in the tire radial direction from the bead toe 5a to the maximum tire width position W, the bead toe 5a to the maximum thickness position 36 of the convex portion 30 in the tire radial direction is too small, it may be difficult to ensure the rigidity of the tire side portion 20 appropriately. That is, when a load is applied, the tire side portion 20 is most likely to flex near the tire maximum width position W. It is effective to ensure However, when the distance Hm from the bead toe 5a to the maximum thickness position 36 is less than 0.4 times the height H from the bead toe 5a to the tire maximum width position W, the maximum thickness position 36 of the protrusion 30 is , the tire maximum width position W may be positioned too far inward in the tire radial direction. In this case, it becomes difficult to ensure the rigidity of the tire side portion 20 in the vicinity of the tire maximum width position W by the convex portion 30 , and thus it becomes difficult to effectively ensure the rigidity of the tire side portion 20 by the convex portion 30 . There is fear.

Further, when the distance Hm in the tire radial direction from the bead toe 5a to the maximum thickness position 36 is greater than 1.2 times the height H in the tire radial direction from the bead toe 5a to the maximum tire width position W, Since the distance Hm in the tire radial direction to the maximum thickness position 36 of the convex portion 30 is too large, it may be difficult to ensure the rigidity of the tire side portion 20 appropriately. That is, when the distance Hm from the bead toe 5a to the maximum thickness position 36 of the protrusion 30 is too large, the maximum thickness position 36 of the protrusion 30 is positioned significantly outside the tire maximum width position W in the tire radial direction. There is a risk of overdoing it. In this case as well, the maximum thickness position 36 of the convex portion 30 is located too far inside the tire maximum width position W in the tire radial direction. is difficult to ensure by the projections 30 , it may be difficult to effectively ensure the rigidity of the tire side portion 20 by the projections 30 .

On the other hand, the distance Hm from the bead toe 5a to the maximum thickness position 36 of the convex portion 30 is within the range of 0.4 to 1.2 times the height H from the bead toe 5a to the tire maximum width position W. In the case where the convex portion 30 is formed so as to be the same, the rigidity of the tire side portion 20 in the vicinity of the tire maximum width position W can be ensured more reliably. As a result, the rigidity of the tire side portion 20 can be more effectively secured by the convex portion 30, and the durability of the tire side portion 20 can be secured more reliably. As a result, deterioration of durability can be suppressed more reliably.

In addition, the bead core 11 has a width W0 of the layer having the largest number of rows among a plurality of layers formed by winding the bead wire 12 in the tire circumferential direction, and a width W1 of the innermost layer in the tire radial direction. and the width W2 of the outermost layer in the tire radial direction satisfy the relationships of W1>W2 and W2≦(0.5×W0), so it is possible to prevent the rim from coming off during rim assembly. That is, when W1≦W2 or W2>(0.5×W0), the width of the outer end of the bead core 11 in the tire radial direction becomes too large. There is a risk that the rigidity in the vicinity of the radially outer end of the tire may become too high. In this case, when the pneumatic tire 1 is mounted on the rim, a rotational force is generated with the position of the bead portion 5 near the outer end in the tire radial direction of the bead core 11 in the tire radial direction and the portion where the rim flange abuts as a fulcrum. When this occurs, it becomes difficult to prevent detachment from the rim due to this rotational force, and there is a risk that the resistance to detachment from the rim will be reduced.

On the other hand, when the plurality of layers formed on the bead core 11 satisfy the relationship of W1>W2 and W2≦(0.5×W0), It is possible to suppress the rigidity from becoming too high in the vicinity of the end of the . As a result, it is possible to suppress detachment from the rim due to a rotational force around a position where the rim flange abuts against the position near the radially outer end of the bead core 11 in the tire radial direction of the bead portion 5 . As a result, the rim detachment resistance can be ensured.

In the bead core 11, the inner angles α and β of the corners located at both ends of the inner side in the tire radial direction of the outer shell shape 13 satisfy the relationship of α>90° and β>90°. It can keep its shape well. That is, if the internal angles α and β of the contour 13 of the bead core 11 satisfy α≦90° or β≦90°, it becomes difficult to reduce the total number of turns of the bead wire 12, and the bead core 11 It may be difficult to reduce the mass of the Further, when the internal angles α and β of the contour 13 of the bead core 11 are α≦90° or β≦90°, the bead wires positioned at both ends of the inner side of the contour 13 in the tire radial direction 12 may be easily affected by the flow of rubber during vulcanization molding during manufacturing of the pneumatic tire 1 . In this case, it becomes difficult to maintain the shape of the bead core 11 after vulcanization molding, and it may become difficult to maintain the number of turns of the bead wire 12 in the innermost layer in the tire radial direction of the bead core 11 .

On the other hand, when the internal angles α and β of the contour 13 of the bead core 11 satisfy the relationships α>90° and β>90°, the total number of turns of the bead wire 12 is reduced to reduce the mass of the bead core 11. can be reduced, and the influence of the rubber flow on the bead wire 12 during vulcanization molding can be suppressed. As a result, the number of turns of the bead wire 12 in the innermost layer of the bead core 11 in the tire radial direction can be more reliably maintained while reducing the mass of the pneumatic tire 1 more reliably. As a result, the rim detachment resistance can be ensured while reducing the mass more reliably.

In addition, the bead core 11 is such that the peripheral length L0, the length L1, the length L2, and the length 3 of the outer shell shape 13 are 0.25≦{(L1+L2)/L0}≦0.40 and 1 In order to satisfy the relationship of 0≦{(L1+L2)/(2×L3)}≦2.5, the shape of the bead core 11 should be a shape that can reduce the mass while ensuring resistance to rim detachment. can. That is, the circumferential length L0, the length L1, the length L2, and the length 3 of the outer shape 13 of the bead core 11 are 0.25>{(L1+L2)/L0} or 1.0>{ (L1+L2)/(2×L3)}, the length L1 and the length L2 of the outer shell 13 are too short, and it may be difficult to secure the rim resistance. That is, in the bead core 11, the position corresponding to the inner side in the tire radial direction of the outer shape 13 and the position corresponding to the side connected to the inner side in the tire radial direction of the outer shape 13 are the rim detachment resistance during run-flat running. If the lengths L1 and L2 of these sides are too short, it may be difficult to ensure resistance to rim detachment during run-flat running. Further, the circumferential length L0, the length L1, the length L2, and the length 3 of the outer shape 13 of the bead core 11 satisfy {(L1+L2)/L0}>0.40, or {(L1+L2)/ (2×L3)}>2.5, the length L1 and the length L2 of the outer shell 13 are too long, and the mass of the bead core 11 may be too large. In this case, it may be difficult to reduce the mass of the pneumatic tire 1 even if the bead filler is omitted.

On the other hand, the circumferential length L0, the length L1, the length L2, and the length 3 of the outer shape 13 of the bead core 11 are 0.25≦{(L1+L2)/L0}≦0.40, and When the relationship 1.0≦{(L1+L2)/(2×L3)}≦2.5 is satisfied, the shape of the bead core 11 is changed to a shape that can reduce the mass and ensure the resistance to rim detachment. In particular, it is possible to ensure resistance to rim detachment during run-flat running. As a result, the rim detachment resistance can be ensured while reducing the mass more reliably.

In addition, since the average diameter of the bead wires 12 of the bead core 11 is within the range of 0.8 mm or more and 1.8 mm or less, the mass of the bead core 11 is suppressed from becoming too large, and the bead core 11 is more reliably restrained. power can be secured. In other words, if the average diameter of the bead wires 12 is less than 0.8 mm, the average diameter of the bead wires 12 is too small, and it may be difficult to secure the rigidity of the bead wires 12 . In this case, it becomes difficult to secure the restraining force at the bead core 11, and it may become difficult to secure the resistance to rim detachment. Also, if the average diameter of the bead wires 12 is larger than 1.8 mm, the average diameter of the bead wires 12 is too thick, and the mass of the bead core 11 may become too large. It is likely to become difficult.

On the other hand, when the average diameter of the bead wires 12 is in the range of 0.8 mm or more and 1.8 mm or less, the rigidity of the bead wires 12 is ensured while suppressing the mass of the bead core 11 from becoming too large. , the binding force at the bead core 11 can be ensured more reliably. As a result, the rim detachment resistance can be ensured while reducing the mass more reliably.

[Embodiment 2]
The pneumatic tire 1 according to Embodiment 2 has substantially the same configuration as the pneumatic tire 1 according to Embodiment 1, but is characterized in that the convex portion 30 is inclined in the tire circumferential direction with respect to the tire radial direction. There is Since other configurations are the same as those of the first embodiment, description thereof is omitted and the same reference numerals are given.

FIG. 6 is a plan view of essential parts showing the tire side surface 21 of the pneumatic tire 1 according to Embodiment 2. FIG. In the pneumatic tire 1 according to Embodiment 2, as in the pneumatic tire 1 according to Embodiment 1, the bead portion 5 is not provided with the bead filler, and the tire side portion 20 is provided with the side reinforcing rubber 25. A plurality of protrusions 30 are formed on the tire side portion 20 so as to protrude from the tire side surface 21 and extend along the tire side surface 21 . Moreover, in Embodiment 2, the convex part 30 formed in the tire side part 20 inclines in the tire circumferential direction with respect to the tire radial direction. Therefore, the positions of the outer ends 31o and the inner ends 31i of the protrusions 30 in the tire circumferential direction are different from each other.

In the plurality of protrusions 30 formed on one tire side surface 21, the inclination direction in the tire circumferential direction with respect to the tire radial direction alternates among the plurality of protrusions 30 arranged side by side in the tire circumferential direction. The convex portions 30 arranged adjacent to each other in the tire circumferential direction are inclined in opposite directions. For this reason, among the plurality of protrusions 30 formed on one tire side surface 21, the protrusions 30 adjacent to each other in the tire circumferential direction are arranged in a V-shape. In other words, the plurality of protrusions 30 formed on one tire side surface 21 are adjacent to each other in the tire circumferential direction in the direction of inclination in the tire radial direction when heading in a predetermined direction in the tire circumferential direction. and are in opposite directions.

In the pneumatic tire 1 according to Embodiment 2 configured as described above, the bead portion 5 does not have a bead filler, and the tire side portion 20 has Since the protrusions 30 are formed, it is possible to reduce the mass while suppressing deterioration in durability.

Further, since the convex portion 30 is inclined in the tire circumferential direction with respect to the tire radial direction, the length of the convex portion 30 can be increased without increasing the distance in the tire radial direction between the outer end portion 31o and the inner end portion 31i. The length in the present direction can be lengthened. As a result, the surface area of the convex portion 30 can be increased, so heat exchange between the air flowing near the tire side surface 21 and the convex portion 30 can be efficiently performed. Therefore, it is possible to improve the heat dissipation property of the convex portion 30, and it is possible to more reliably prevent the temperature of the members forming the tire side portion 20 from becoming too high. As a result, durability can be improved more reliably.

[Embodiment 3]
The pneumatic tire 1 according to Embodiment 3 has substantially the same configuration as the pneumatic tire 1 according to Embodiment 2, but is characterized in that the convex portions 30 are all inclined in the same direction. Since other configurations are the same as those of the second embodiment, description thereof will be omitted and the same reference numerals will be given.

FIG. 7 is a plan view of essential parts showing the tire side surface 21 of the pneumatic tire 1 according to Embodiment 3. FIG. In the pneumatic tire 1 according to Embodiment 3, as in the pneumatic tire 1 according to Embodiment 2, the bead portion 5 is not provided with the bead filler, and the tire side portion 20 is provided with the side reinforcing rubber 25. A plurality of protrusions 30 are formed on the tire side portion 20 so as to protrude from the tire side surface 21 and extend along the tire side surface 21 . Further, the convex portion 30 is inclined in the tire circumferential direction with respect to the tire radial direction.

Further, the pneumatic tire 1 according to Embodiment 3 is a pneumatic tire 1 with a specified rotation direction when mounted on a vehicle, that is, a specified rotation direction around the rotation axis when the vehicle moves forward. The pneumatic tire 1 is mounted on a vehicle so as to rotate freely. Therefore, the pneumatic tire 1 according to Embodiment 3 has a rotation direction indicator (not shown) that indicates the rotation direction. The rotation direction display portion is configured by, for example, a mark or unevenness provided on the sidewall portion 4 of the tire. In the following description, the first arrival side in the tire rotation direction is the rotation direction side when the pneumatic tire 1 is rotated in the specified direction, and the pneumatic tire 1 is mounted on the vehicle and rotated in the specified direction. It is the side that touches the road surface first or leaves the road surface first. In addition, the later arrival side in the tire rotation direction is the side opposite to the rotation direction when the pneumatic tire 1 is rotated in the designated direction, and the pneumatic tire 1 is mounted on the vehicle and rotated in the designated direction. It is the side that touches the road surface after the portion positioned on the first-arrival side and leaves the road surface after the portion positioned on the first-arrival side.

The pneumatic tire 1 according to Embodiment 3 is thus a pneumatic tire 1 in which the direction of rotation when mounted on a vehicle is specified. , the inclination directions in the tire radial direction when going in a predetermined direction in the tire circumferential direction are all the same. Specifically, the convex portion 30 is inclined with respect to the tire circumferential direction from the inner side to the outer side in the tire radial direction from the first arrival side to the last arrival side in the rotational direction of the pneumatic tire 1 . Therefore, the inner end portion 31i of each convex portion 30 is located on the first arrival side in the tire rotation direction than the outer end portion 31o.

When the pneumatic tire 1 according to Embodiment 3 is mounted on a vehicle, it is mounted on the vehicle so that the direction of rotation when mounted on the vehicle is the designated direction. That is, it is mounted on the vehicle in the direction designated by the rotation direction indicator attached to the sidewall portion 4 . In the pneumatic tire 1 according to Embodiment 3, similarly to the pneumatic tire 1 according to Embodiment 2, a bead filler is omitted from the bead portion 5, and a convex portion 30 is formed on the tire side portion 20. Therefore, it is possible to reduce the mass while suppressing deterioration in durability.

In addition, since the convex portion 30 is inclined with respect to the tire circumferential direction from the inner side to the outer side in the tire radial direction as it goes from the first arrival side to the last arrival side in the rotation direction of the pneumatic tire 1, it is more reliable. can improve heat dissipation. That is, the direction of inclination of the convex portion 30 is inclined from the inner side to the outer side in the tire radial direction as it goes from the first arrival side to the last arrival side in the rotation direction. The direction of flow of the air flowing through the tire is changed by the convex portion 30 from the inner side to the outer side in the tire radial direction. For this reason, the air whose temperature has increased due to the heat exchange performed by the protrusions 30 is efficiently discharged outward in the tire radial direction. As a result, the convex portion 30 can more efficiently exchange heat with the air flowing in the vicinity of the tire side surface 21, and the heat dissipation can be improved more reliably. Therefore, it is possible to more reliably prevent the temperature of the members forming the tire side portion 20 from becoming too high. As a result, durability can be improved more reliably.

[Embodiment 4]
The pneumatic tire 1 according to Embodiment 4 has substantially the same configuration as the pneumatic tire 1 according to Embodiment 3, but is characterized in that the convex portion 30 has a bent portion 40 . Since other configurations are the same as those of the third embodiment, description thereof will be omitted and the same reference numerals will be given.

FIG. 8 is a plan view of essential parts showing the tire side surface 21 of the pneumatic tire 1 according to Embodiment 4. FIG. FIG. 9 is a detailed view of the C section in FIG. In the pneumatic tire 1 according to Embodiment 4, as in the pneumatic tire 1 according to Embodiment 3, the bead portion 5 is not provided with the bead filler, and the tire side portion 20 is provided with the side reinforcing rubber 25. A plurality of protrusions 30 are formed on the tire side portion 20 so as to protrude from the tire side surface 21 and extend along the tire side surface 21 . Further, in the pneumatic tire 1 according to Embodiment 4, similarly to the pneumatic tire 1 according to Embodiment 3, the direction of rotation when mounted on a vehicle is designated, and the convex portion 30 is positioned from the first-arrival side in the direction of rotation. It is inclined with respect to the tire circumferential direction in the direction from the inner side to the outer side in the tire radial direction toward the rear landing side.

Further, each convex portion 30 has at least one bending portion 40 at a position where the extending direction of the convex portion 30 changes, and each convex portion 30 has a plurality of bending portions 40 . The number of bent portions 40 included in one convex portion 30 is preferably in the range of 2 or more and 4 or less. Moreover, each convex portion 30 has a plurality of extension portions 50 partitioned by the bent portions 40 . The extending portion 50 in this case is formed to extend along the tire side surface 21 in a single arc shape or a single linear shape. In addition, the single arc shape referred to here means the difference in the relative ratio of the curvature radii between the positions where the curvature radii are the largest and the smallest when the extending portion 50 is formed in a curved shape. is 200% or less. Further, the single linear shape refers to a shape in which the change in the extending direction of the extending portion 50 is 5° or less. Further, when the two extending portions 50 partitioned by the bending portion 40 are both in the shape of a single arc, the position of the inflection point is the bending portion 40, and the extending portions 50 have a very small radius of curvature. In the case of connecting by an arc, the bent portion 40 is the range where the arc with the smallest radius of curvature is formed.

In Embodiment 4, each convex portion 30 has two bent portions 40 , and has three extension portions 50 due to the two bent portions 40 . That is, the convex portion 30 has three extension portions 50 , a first extension portion 51 , a second extension portion 52 and a third extension portion 53 . Among these, the first extension portion 51 is the extension portion 50 having the longest length among the plurality of extension portions 50 of one convex portion 30. That is, the first extension portion 51 is , the length of which is longer than that of the second extension portion 52 and the third extension portion 53 . Also, the second extension portion 52 is the extension portion 50 that is continuous from the first extension portion 51 via the bent portion 40 . In addition, the third extension portion 53 is located on the side opposite to the side where the first extension portion 51 is located in the extension direction of the second extension portion 52. The extending portion 50 continues from the . That is, among the plurality of extension portions 50, the first extension portion 51 and the third extension portion 53 are located on one end side in the extension direction of the first extension portion 51 and the third extension portion 53. The second extending portion 52 is partitioned by the bending portion 40 at both ends in the extending direction of the second extending portion 52 .

In addition, the first extension portion 51 is arranged on the outermost side in the tire radial direction among the plurality of extension portions 50 , and the convex portion 30 extends from the first extension portion 51 side to the third extension portion 53 side. , it is inclined with respect to the tire circumferential direction from the tire radial outer side toward the tire radial inner side. Therefore, the second extension portion 52 is arranged radially inward of the first extension portion 51 , and the third extension portion 53 is arranged radially inward of the second extension portion 52 . ing.

In addition, since the plurality of protrusions 30 are all inclined in the same direction in the tire radial direction when heading in the predetermined direction in the tire circumferential direction, the plurality of protrusions 30 have the same inclination direction. All of the first extending portions 51 also have the same inclination direction in the tire radial direction with respect to the tire circumferential direction. Specifically, the first extending portion 51 is inclined with respect to the tire circumferential direction from the inner side to the outer side in the tire radial direction from the first arrival side to the last arrival side in the rotational direction of the pneumatic tire 1 . ing. Similarly, the second extending portion 52 and the third extending portion 53 extend from the inside to the outside in the tire radial direction from the first arrival side to the last arrival side in the rotation direction of the pneumatic tire 1 . It is slanted with respect to the direction.

Further, among the plurality of extension portions 50 of the convex portion 30, the inclination of the second extension portion 52 in the tire radial direction with respect to the tire circumferential direction is is greater than the inclination to In addition, the second extension portion 52 has a greater inclination in the tire radial direction with respect to the tire circumferential direction than the third extension portion 53 . That is, the first extending portion 51, the second extending portion 52, and the third extending portion 53 are inclined in the same direction in the tire radial direction when heading in a predetermined direction in the tire circumferential direction. However, the second extending portion 52 has the largest inclination in the tire radial direction with respect to the tire circumferential direction. The second extending portion 52 having the largest inclination in the tire radial direction with respect to the tire circumferential direction is arranged at a position straddling the tire maximum width position W (see FIG. 1) on the tire side surface 21 in the tire radial direction.

The convex portion 30 formed in this manner has two convex portion end position lines Pc extending in the tire radial direction that pass through mutually different end portions 31 among both end portions 31 in the extending direction of the convex portion 30. The relative angle Rc in the tire circumferential direction, that is, the angle Rc formed by the two protrusion end position lines Pc is within the range of 6% or more and 50% or less of the angle 2π of one round in the tire circumferential direction. there is That is, each of the plurality of protrusions 30 arranged on one tire side portion 20 extends in the tire circumferential direction with an angle Rc of 6% or more and 50% or less of the angle 2π of one circumference in the tire circumferential direction. ing. The angle Rc defined in this manner is the angle in the tire circumferential direction within the range in which one projection 30 is arranged, that is, the extension angle of the projection 30 in the tire circumferential direction.

In the convex portion 30, the angle Rc with respect to the angle 2π of one round in the tire circumferential direction is preferably in the range of 8% or more and 40% or less, and more preferably in the range of 10% or more and 30% or less. It is good to be

In addition, the first extension portion 51 has two first extension portion end portions extending in the tire radial direction passing through mutually different end portions 51a among both end portions 51a in the extension direction of the first extension portion 51. The relative angle Re between the position lines Pe in the tire circumferential direction, that is, the angle Re formed by the two first extending portion end position lines Pe is 0.60 ≤ (Re/Rc )≦0.90. This angle Re is the angle in the tire circumferential direction in the range in which one first extension portion 51 is arranged, that is, the extension angle of the first extension portion 51 in the tire circumferential direction. The angle Re of the first extension portion 51 with respect to the angle Rc of the convex portion 30 is preferably within the range of 0.70≦(Re/Rc)≦0.85.

The first extension portion 51 formed in this way has a length in the extension direction of the first extension portion 51 that is greater than the length of the second extension portion 52 in the extension direction of the second extension portion 52 . It is within the range of 1.5 times or more and 30 times or less. Furthermore, the length of the first extension portion 51 in the extension direction of the first extension portion 51 is 1.2 times the length of the third extension portion 53 in the extension direction of the third extension portion 53. It is within the range of 25 times or less. The length of the first extension portion 51 is preferably in the range of 3 to 20 times the length of the second extension portion 52, and in the range of 5 to 15 times the length of the second extension portion 52. is more preferred. Also, the length of the first extension portion 51 is preferably in the range of 2 to 20 times the length of the third extension portion 53, and in the range of 3 to 15 times the length of the third extension portion 53. is more preferred.

Moreover, the thickness of the protrusion 30 in a plan view and the height from the tire side surface 21 of the protrusion 30 are different for each extending portion 50 . That is, the first extension portion 51, the second extension portion 52, and the third extension portion 53 of the convex portion 30 have different thicknesses and heights. In the fourth embodiment, the average thickness of the second extension portion 52 is thicker than the average thickness of the first extension portion 51 and the average thickness of the third extension portion 53. The average height of the extension portion 52 is also higher than the average height of the first extension portion 51 and the average height of the third extension portion 53 .

Further, the maximum thickness of the second extension portion 52 is greater than that of the first extension portion 51 and the third extension portion 53 . Specifically, the maximum thickness of the second extension portion 52 is in the range of 1.5 to 5 times the maximum thickness of the first extension portion 51 . The second extension portion 52 also has a maximum thickness greater than the maximum thickness of the third extension portion 53 . Therefore, the portion of the convex portion 30 that has the maximum thickness is located at the second extension portion 52 . Also, the maximum thickness of the convex portion 30 is preferably in the range of 1.5 mm to 10 mm, and more preferably in the range of 2.0 mm to 10 mm.

In addition, when the portion of the protrusion 30 connected to the tire side surface 21, that is, the root portion of the protrusion 30 is formed in an arc shape or a chamfered shape for the purpose of reducing stress concentration or manufacturing convenience, , the thickness of the convex portion 30 preferably includes arc-shaped and chamfered portions.

Since the heights of the protrusions 30 differ for each extending portion 50, in other words, the height from the tire side surface 21 differs depending on the position of the protrusions 30, and the height from the tire side surface 21, How the height changes differs for each extension portion 50 . For example, the first extension portion 51 has an end portion whose height from the tire side surface 21 is located on the side opposite to the side on which the second extension portion 52 is located from the side on which the second extension portion 52 is located. It becomes lower as it goes to 51a. The first extension portion 51 formed in this manner is disposed radially outward of the second extension portion 52 and is inclined in the tire radial direction with respect to the tire circumferential direction. 51, the height from the tire side surface 21 decreases toward the tire radial direction outer side, and the height from the tire side surface 21 is the lowest at the position of the tire radial direction outer end 51a. .

Similarly to the first extension portion 51, the third extension portion 53 also has a height from the tire side surface 21 that is the second extension portion 52 is located from the side where the second extension portion 52 is located. It becomes lower toward the end located on the opposite side of the side. The third extending portion 53 formed in this manner is disposed radially inward of the second extending portion 52 and is inclined in the tire radial direction with respect to the tire circumferential direction. 53 has a lower height from the tire side surface 21 as it goes inward in the tire radial direction, and the height from the tire side surface 21 is lowest at the position of the end portion on the inner side in the tire radial direction.

In the pneumatic tire 1 according to Embodiment 4, the convex portion 30 has at least one bent portion 40 and has a plurality of extension portions 50 as described above. can be improved, and the rigidity of the tire side portion 20 can be secured. That is, since the convex portion 30 has the bent portion 40 , a plurality of extension portions 50 are formed, so that each extension portion 50 can have a different inclination with respect to the tire circumferential direction and the tire radial direction. As a result, the inclination of the extending portion 50 can be set to an angle that emphasizes heat dissipation or an angle that emphasizes ensuring the rigidity of the tire side portion 20 for each position in the tire radial direction of the tire side portion 20 . can. Therefore, it is possible to more reliably prevent the temperature of the members forming the tire side portion 20 from becoming too high, and to ensure the rigidity of the tire side portion 20 more effectively by the protrusions 30 . As a result, deterioration of durability can be suppressed more reliably.

In addition, since the inclination of the second extending portion 52 in the tire radial direction with respect to the tire circumferential direction is larger than that of the first extending portion 51 and the third extending portion 53, the convex portion 30 can more reliably extend to the tire side portion. 20 stiffness can be ensured. That is, the position of the second extension portion 52 in the tire radial direction is located between the first extension portion 51 and the third extension portion 53, and the tire maximum width position W on the tire side surface 21 is It is arranged at a position straddling the tire radial direction. That is, the second extending portion 52 is arranged at a position where the tire side portion 20 is most flexible. Therefore, by making the inclination of the second extending portion 52 in the tire radial direction with respect to the tire circumferential direction larger than those of the first extending portion 51 and the third extending portion 53, the tire side portion 20 is most likely to bend. Positional rigidity can be improved more reliably. As a result, the rigidity of the tire side portion 20 can be ensured more reliably, and a decrease in steering stability can be suppressed, and a decrease in durability during run-flat running can be suppressed. As a result, deterioration of durability can be suppressed more reliably.

In addition, since the length of the first extension portion 51 of the protrusion 30 is longer than that of the second extension portion 52 and the third extension portion 53, the heat dissipation property of the protrusion 30 can be more reliably improved. can be done. That is, when the pneumatic tire 1 rotates, the peripheral speed increases toward the tire radial direction outer side, so the difference in relative speed between the tire side surface 21 and the surrounding air also increases toward the tire radial direction outer side. . Therefore, by maximizing the length of the first extending portion 51 arranged on the outermost side in the tire radial direction, the tire side surface in the region where the circumferential speed is high and heat exchange can be performed efficiently. Heat exchange between the air flowing near 21 and the convex portion 30 can be efficiently performed. Therefore, it is possible to more reliably improve the heat dissipation performance of the convex portion 30, and to more reliably prevent the temperature of the members forming the tire side portion 20 from becoming too high. As a result, durability can be improved more reliably.

In addition, since the maximum thickness of the second extension portion 52 is thicker than the maximum thickness of the first extension portion 51 and the maximum thickness of the third extension portion 53, the convex portion 30 can more reliably extend the tire side portion 20. of rigidity can be ensured. That is, by making the maximum thickness of the second extension portion 52 arranged at the most flexible position in the tire side portion 20 thicker than the first extension portion 51 and the third extension portion 53, the tire side portion It is possible to more reliably improve the rigidity of the position where the bending is most likely in 20 . As a result, the rigidity of the tire side portion 20 can be ensured more reliably, and a decrease in steering stability can be suppressed, and a decrease in durability during run-flat running can be suppressed. As a result, deterioration of durability can be suppressed more reliably.

[Modification]
In the pneumatic tires 1 according to Embodiments 1 to 4 described above, the bead wires 12 of the bead core 11 have a laminated structure of 3+4+3+2+1, but the bead wires 12 may be laminated with a structure other than this. . FIG. 10 is a modification of the pneumatic tire 1 according to Embodiment 1, and is an explanatory diagram of a modification of the laminated structure of the bead wires 12. As shown in FIG. The laminated structure of the bead wires 12 of the bead core 11 may be, for example, a baled 4+5+4+3+2+1 structure as shown in FIG. 10(a), or a baled 3+4+3+2 structure as shown in FIG. It may be a 3+4+4+3+2+1 structure of bale stacking as shown in FIG. 10(c). In addition, the laminated structure of the bead wires 12 may have portions other than bales. For example, as shown in FIG. Adjacent layers may have a 3+4+4+3+2+1 structure in which adjacent layers are stacked in series instead of bale stacking (a stacking method in which circumferential portions adjacent in the tire radial direction are stacked vertically in the tire width direction).

In the laminated structures shown in FIGS. 10A to 10D, at least a portion of the laminated structure is laminated in a bale pattern, so the bead wires 12 are more preferable than the bead wires 12 having a structure in which the whole is laminated in series. The filling rate of the bead wires 12 can be increased by arranging them densely. 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 ensuring the rigidity and pressure resistance of the bead portion 5 satisfactorily.

Even when the laminated structure of the bead wire 12 is different from that of the first embodiment, the widths W0, W1, and W2 preferably satisfy the relationship shown in the first embodiment. It is preferable that L1 and L2 also satisfy the relationship shown in the first embodiment. As long as the widths W0, W1, W2, the circumferential length L0, and the lengths L1, L2 satisfy the relationships shown in the first embodiment, the bead wire 12 may have any laminated structure.

Further, in the pneumatic tire 1 according to Embodiment 4 described above, each convex portion 30 has two bent portions 40, but one convex portion 30 has bent portions 40 other than two. may Regardless of the number of bent portions 40, a plurality of extension portions 50 can be provided on the projection portion 30 by forming the bent portions 40 on the projection portion 30, and each extension portion 50 can have a different inclination. Therefore, the deterioration of durability can be more reliably suppressed by the protrusions 30 .

Further, in the pneumatic tires 1 according to Embodiments 1 to 4 described above, the convex portion 30 is formed on the tire side portion 20 on the outer side in the vehicle mounting direction. The protrusions 30 may also be formed on the portion 20, that is, the protrusions 30 may be formed on the tire side surfaces 21 of the tire side portions 20 on both sides in the tire width direction. By forming the protrusions 30 on the tire side surfaces 21 on both sides in the tire width direction, heat can be dissipated by the protrusions 30 at the tire side portions 20 on both sides in the tire width direction, and the tire side portions 20 on both sides in the tire width direction. of rigidity can be ensured. This makes it possible to more reliably suppress deterioration in durability.

Alternatively, the convex portion 30 may be formed only on the tire side surface 21 on the inner side in the vehicle mounting direction. Since the tire side surface 21 on the inner side in the mounting direction of the vehicle does not face the outer side of the vehicle, it is difficult to see from the outside of the vehicle. Therefore, when the convex portion 30 is formed on the tire side surface 21 on the inner side in the vehicle mounting direction, the convex portion 30 is also difficult to visually recognize. Accordingly, by forming the convex portion 30 on the tire side surface 21 on the inner side in the vehicle mounting direction, it is possible to reduce the mass while suppressing deterioration in durability without affecting the appearance of the vehicle.

As described above, depending on the tire side portion 20 in which the convex portion 30 is provided, the obtained secondary effect is different. may be formed in at least one tire side portion 20 among the tire side portions 20 located in the .

[Example]
11A to 11C are charts showing the results of performance evaluation tests of pneumatic tires. In the following, the pneumatic tire 1 described above was tested for a conventional pneumatic tire, a pneumatic tire 1 according to the present invention, and a comparative example pneumatic tire for comparison with the pneumatic tire 1 according to the present invention. The performance evaluation test will be explained. The performance evaluation tests were performed on mass, durability, and rim detachment resistance tests.

The performance evaluation test was performed using a pneumatic tire 1 having a tire designation of 205/55R16 size defined by JATMA. As for the evaluation method of each test item, the mass of each test tire was measured, and the measured mass was expressed as an index with 100 as the conventional example described later. Regarding the mass of the pneumatic tire 1, the smaller the numerical value, the lighter the mass per tire, indicating that the pneumatic tire 1 is superior in terms of weight reduction.

The durability was evaluated by assembling the test tire on a JATMA standard rim wheel with a rim size of 16 x 6.5J, and mounting the test tire on a test vehicle with an engine displacement of 2000cc with air pressure set to 0kPa, and running at 80km/h. and measured the distance until the test driver felt abnormal vibrations due to tire failure and stopped driving. The durability is indicated by indexing the measured distance to 100 for the conventional example described later. The higher the value, the better the durability during run-flat running and the higher the run-flat running performance.

In addition, the rim detachment resistance was evaluated by mounting the test tire on a JATMA standard rim wheel with a rim size of 16 x 6.5J, and mounting the test tire on a test vehicle with a displacement of 2000cc with air pressure set to 0 kPa. A turn evaluation was performed, and the speed was gradually increased to measure the speed at which the rim came off. The rim detachment resistance is shown as an index with the measured speed being 100 for the conventional example described later. The larger this value is, the more difficult it is for rim detachment to occur, indicating that the rim detachment resistance is excellent.

In the performance evaluation test, a conventional pneumatic tire, which is an example of a conventional pneumatic tire, Examples 1 to 6, 9, 11 to 15, which is a pneumatic tire 1 according to the present invention, and the air according to the present invention 16 types of pneumatic tires of Comparative Examples 1 and 2 and Reference Example 10, which are pneumatic tires to be compared with the pneumatic tire 1, were tested. Among these, the pneumatic tire of the conventional example has a bead filler, and the tire side portion 20 is not formed with the convex portion 30 . Further, the pneumatic tire of Comparative Example 1 does not have a bead filler, and although the protrusions 30 are formed on the tire side portion 20, the maximum thickness of the protrusions 30 is 1 mm. Further, the pneumatic tire of Comparative Example 2 does not have a bead filler, and although the tire side portion 20 is formed with the convex portion 30, the shape of the bead core 11 in the tire meridional cross section is a wedge shape on the outer diameter side ( The shape of the bead core 11 is square.

On the other hand, Examples 1 to 6, 9, and 11 to 15, which are examples of the pneumatic tire 1 according to the present invention, do not have any bead filler, and the tire side portion 20 is formed with the convex portion 30. The maximum thickness of the convex portion 30 is 1.5 mm or more, and the shape of the bead core 11 is a wedge shape on the outer diameter side. Furthermore, the pneumatic tire 1 according to Examples 1 to 6, 9, 11 to 15 and Reference Example 10 has the number of bent portions 40 of the convex portion 30, the length Lc of the convex portion 30 in the tire radial direction, the convex The position of the maximum thickness position 36 of the portion 30 in the tire radial direction, and the inclination of the second extending portion 52 in the tire radial direction with respect to the inclination of the first extending portion 51 and the third extending portion 53 in the tire radial direction. size, the length of the first extension portion 51 relative to the length of the second extension portion 52 and the length of the third extension portion 53, the maximum thickness of the first extension portion 51 and the length of the third extension portion 53 The maximum thickness of the second extension portion 52 with respect to the maximum thickness, the internal angles α and β of the contour shape 13 of the bead core 11, the peripheral length L0 of the contour shape 13 of the bead core 11, and the lengths L1, L2, and L3 {(L1+L2) /L0} and {(L1+L2)/(2×L3)}, the average diameter of the bead wires 12, etc. are different.

As a result of conducting a performance evaluation test using these pneumatic tires 1, as shown in FIGS. It has been found that the weight can be reduced and the decrease in durability can be suppressed by using the In other words, the pneumatic tires 1 according to Examples 1 to 6, 9 and 11 to 15 can reduce the mass while suppressing deterioration in durability.

1 pneumatic tire 2 tread portion 3 shoulder portion 4 sidewall portion 5 bead portion 5a bead toe 5b bead heel 6 carcass layer 6a carcass body portion 6b folded portion 7 belt layer 8 belt reinforcing layer 9 inner liner 10 ground contact surface 11 bead core 12 bead wire 13 outer shell Shape 16 Circumferential groove 17 Lug groove 20 Tire side portion 21 Tire side surface 25 Side reinforcing rubber 30 Protruding portion 31 End portion 31o Outer end portion 31i Inner end portion 32 Height change portion 33 Maximum height region 34 Thickness change portion 35 Maximum thickness region 36 Maximum thickness position 40 Bending portion 50 Extension portion 51 First extension portion 52 Second extension portion 53 Third extension portion

Claims (9)

a tread portion extending in the tire circumferential direction and formed in an annular shape;
a pair of tire side portions disposed on both sides of the tread portion in the tire width direction;
a pair of bead portions disposed radially inward of each of the tire side portions;
a bead core disposed in the bead portion;
a carcass layer spanning between the pair of bead portions;
a side reinforcing rubber disposed in the tire side portion;
a plurality of projections formed on at least one of the tire side portions of the pair of tire side portions, projecting from a tire side surface that is a surface of the tire side portion and extending along the tire side surface;
with
The bead core is formed so that the width in the tire width direction becomes narrower toward the outside in the tire radial direction from the portion where the width in the tire width direction is the maximum width,
The carcass layer includes a carcass body portion that spans between the pair of bead portions, and a fold that is formed continuously from the carcass body portion and is folded back from the inner side in the tire width direction of the bead core to the outer side in the tire width direction at the bead portion. and
The folded portion is folded back while being bent along the peripheral edge of the bead core, and extends outward in the tire radial direction from the position of the outer end portion of the bead core in the tire radial direction while contacting the carcass body portion,
The convex portion has a maximum thickness of 1.5 mm or more, and a thickness at a position where the height from the tire side surface is the maximum height is 0.7 times or more the maximum thickness of 1.0. within the range of less than or equal to
The convex portion has a bent portion at a position where the direction in which the convex portion extends changes, and has a plurality of extended portions by bending at the bent portion,
The plurality of extension portions includes a first extension portion, a second extension portion which is the extension portion continuous from the first extension portion via the bent portion, and the second extension portion. a third extension portion, which is the extension portion located on the side opposite to the side on which the first extension portion is located in the extension direction and which is continuous from the second extension portion via the bent portion; has
The pneumatic tire, wherein the second extension portion has a greater inclination in the tire radial direction with respect to the tire circumferential direction than the first extension portion and the third extension portion . In the convex portion, the distance in the tire radial direction from the tire radially outer end to the tire radially inner end is equal to the tire radial direction distance from the tire radially inner end of the bead portion to the tire maximum width position. 2. The pneumatic tire according to claim 1, which is in the range of 0.2 times or more and 1.0 times or less of the height at . In the convex portion, the distance in the tire radial direction from the radially inner end of the bead portion to the position where the convex portion has the maximum thickness is the maximum width of the tire from the radially inner end of the bead portion in the tire radial direction. 3. The pneumatic tire according to claim 1 or 2, arranged at a position within a range of 0.4 to 1.2 times the height in the tire radial direction to the position. The pneumatic tire is mounted on the vehicle so as to rotate in a specified rotational direction around a rotation axis when the vehicle moves forward,
4. The convex portion according to any one of claims 1 to 3, wherein the convex portion is inclined with respect to the tire circumferential direction from the inner side to the outer side in the tire radial direction as it goes from the first arrival side to the last arrival side in the rotation direction. pneumatic tires. The pneumatic tire according to any one of claims 1 to 4, wherein the first extension portion is longer than the second extension portion and the third extension portion. The pneumatic tire according to any one of claims 1 to 5, wherein the second extension portion has a maximum thickness greater than that of the first extension portion and the third extension portion. The bead core is composed of at least one bead wire wound in the tire circumferential direction, and in the tire meridional cross section, at least one row of a plurality of wound portions of the bead wire arranged in the tire width direction and a plurality of layers overlapping in the tire radial direction. and
Among the plurality of layers, the width W0 of the layer having the largest number of rows included, the width W1 of the innermost layer in the tire radial direction, and the width W2 of the outermost layer in the tire radial direction are W1>W2, and , W2≦(0.5×W0), and among the plurality of layers, the layer having the largest number of rows is located radially inward of the center position of the bead core in the tire radial direction. The pneumatic tire according to any one of claims 1-6 . The bead core has corners located at both ends of the tire radially inner side of the outer shape when a polygon formed by common tangents of a plurality of circumferential portions of the bead wire in the meridional cross section of the tire is taken as the outer shape of the bead wire. The internal angles α and β of the part satisfy the relationships α>90° and β>90°,
The peripheral length L0 of the outer shape, the length L1 of the inner side in the tire radial direction of the outer shape, the length L2 of the inclined side on the bead toe side connected to the inner side in the tire radial direction of the outer shape, and The length L3 of the inclined side on the bead heel side connected to the inner side in the tire radial direction of the outer shape is 0.25≤{(L1+L2)/L0}≤0.40 and 1.0≤{(L1+L2). /(2×L3)}≦2.5. The pneumatic tire according to claim 7 . The pneumatic tire according to claim 7 or 8 , wherein the average diameter of said bead wires is in the range of 0.8 mm or more and 1.8 mm or less.

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