JP2022158301A - pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire capable of being vulcanization-molded in a short time even when a bead part is thick.SOLUTION: A pneumatic tire 1 comprises: a tread part 2 with a ground contact surface; a pair of sidewall parts 3 extending from both sides of the tread part 2 in a tire axial direction thereof to an inner side in a tire radial direction; and a bead part 4 having a bead core 5 in the inner side in the tire radial direction of either of the sidewall parts 3. The tread part 2 includes a tread rubber 2G constituting the ground contact surface. The bead part 4 includes a bead reinforcement layer 11 extending toward an outer side in the tire radial direction from the bead core 5. A thickness t1 of the bead part 4 at a center position 11c in the tire radial direction of the bead reinforcement layer 11 is larger than a thickness t2 of the tread rubber 2G at a tire equator position C. The bead reinforcement layer 11 includes a metal member.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pneumatic tire having beads.

Conventionally, a pneumatic tire having a bead reinforcing layer in a bead portion is known. For example, Patent Literature 1 below proposes a pneumatic tire in which a bead reinforcing layer provided with reinforcing cords is disposed on the axially outer side of the turn-up portion of the carcass ply.

JP 2018-118606 A

However, in recent years, there has been a tendency to increase the thickness of the bead portion in order to improve the durability, and there has been a problem that the time required for vulcanization molding becomes longer.

SUMMARY OF THE INVENTION The present invention has been devised in view of the actual situation as described above, and its main object is to provide a pneumatic tire that can be vulcanized and molded in a short time even when the bead portion has a large thickness. .

The present invention provides a pneumatic tire comprising a tread portion having a ground contact surface, a pair of sidewall portions extending radially inward from both sides of the tread portion in the tire axial direction, and the sidewall portions. a bead portion having a bead core inside in the tire radial direction, the tread portion having tread rubber forming the ground contact surface, and the bead portion extending outward in the tire radial direction from the bead core. A reinforcing layer is provided, the thickness of the bead portion at the center position in the tire radial direction of the bead reinforcing layer is larger than the thickness of the tread rubber at the tire equator position, and the bead reinforcing layer includes a metal member. characterized by comprising

In the pneumatic tire of the present invention, it is preferable that the inner end of the bead reinforcing layer in the tire radial direction is located radially outside the outer end surface of the bead core in the tire radial direction.

In the pneumatic tire of the present invention, it is preferable that the distance in the tire radial direction between the inner end of the bead reinforcing layer and the outer end surface of the bead core is 20 mm or less.

In the pneumatic tire of the present invention, it is preferable that the thickness of the bead portion at the central position of the bead reinforcing layer is 10 mm or more.

In the pneumatic tire of the present invention, it is preferable that the outer end of the bead reinforcing layer in the tire radial direction is located in the sidewall portion radially inward of the maximum width position of the tire.

In the pneumatic tire of the present invention, the distance between the bead reinforcing layer and the outer surface of the sidewall portion at the position of the outer end of the bead reinforcing layer is 60% to 90% of the thickness of the sidewall portion.

In the pneumatic tire of the present invention, the distance between the bead reinforcing layer at the center position of the bead reinforcing layer and the outer surface of the bead portion is the distance between the bead portion at the center position of the bead reinforcing layer. Desirably, it is between 30% and 80% of the thickness.

In the pneumatic tire of the present invention, a carcass extending between the pair of bead portions via the tread portion and the pair of sidewall portions, the carcass including at least one carcass ply, the carcass At least one ply includes a body portion extending from the tread portion through the sidewall portion to the bead core of the bead portion, and a body portion connected to the body portion and surrounding the bead core from the inside to the outside in the axial direction of the tire. Preferably, the bead reinforcing layer is disposed between the main body portion and the folded portion.

In the pneumatic tire of the present invention, it is preferable that the bead reinforcing layer is arranged adjacent to the folded portion.

In the pneumatic tire of the present invention, the carcass ply desirably includes carcass cords made of organic fiber cords.

In the pneumatic tire of the present invention, it is preferable that the metal member is made of copper.

In the pneumatic tire of the present invention, it is preferable that the metal member is a steel cord.

In the pneumatic tire of the present invention, the bead portion has a bead reinforcing layer extending outward in the tire radial direction from the bead core, and the thickness of the bead portion at the center position of the bead reinforcing layer in the tire radial direction is , greater than the thickness of the tread rubber at the tire equator, and the bead reinforcing layer includes a metal member.

In such a pneumatic tire, the heat generated in the bead core during vulcanization molding can be conducted to the entire bead portion via the metal member, and when the bead portion is thicker than the tread rubber, Also, the vulcanization time can be shortened. Therefore, the pneumatic tire of the present invention can be vulcanized in a short time even when the bead portion has a large thickness.

1 is a cross-sectional view showing an embodiment of a pneumatic tire of the present invention; FIG. 4 is an enlarged sectional view of a bead portion 4; FIG.

An embodiment of the present invention will be described in detail below with reference to the drawings.
FIG. 1 shows a cross-sectional view of a pneumatic tire 1 of this embodiment taken along the tire meridian line including a rotating shaft in a normal state. Here, the "normal state" is a no-load state in which the pneumatic tire 1 is mounted on a normal rim and adjusted to a normal internal pressure. Hereinafter, unless otherwise specified, the dimensions and the like of each part of the pneumatic tire 1 are values measured in this normal state.

If there is a standard system including the standard on which the pneumatic tire 1 is based, the "regular rim" is a rim defined for each tire by the standard. Rim", or "Measuring Rim" for ETRTO. If there is no standard system including the standard on which the pneumatic tire 1 is based, the "regular rim" has the smallest rim diameter among the rims that can be assembled and does not cause air leakage, and the most rim among them. A narrow rim.

"Normal internal pressure" is the air pressure determined for each tire by each standard when there is a standard system including the standards on which the pneumatic tire 1 is based. LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO. The "regular internal pressure" is the air pressure determined for each tire by the manufacturer or the like when there is no standard system including the standard on which the pneumatic tire 1 is based.

As shown in FIG. 1, the pneumatic tire 1 of the present embodiment includes a tread portion 2 extending annularly, a pair of sidewall portions 3 on both sides of the tread portion 2 in the tire axial direction, and sidewall portions 3, respectively. and a bead portion 4 on the inner side in the tire radial direction.

The tread portion 2 of the present embodiment constitutes a ground-contacting surface on which the outer surface 2a comes into contact with the road surface during running. The sidewall portions 3 preferably extend inward in the tire radial direction from both sides of the tread portion 2 in the tire axial direction. A buttress portion, for example, is provided between the tread portion 2 and the sidewall portion 3 . The bead portion 4 includes, for example, a portion that contacts the rim when assembled with the rim. The bead portion 4 of this embodiment has a bead core 5 extending annularly. The bead core 5 is made of steel wire, for example.

The tread portion 2 preferably has a tread rubber 2G formed of at least one elastomer layer. The outer surface 2a of the tread rubber 2G of this embodiment constitutes a contact surface. The tread rubber 2G may have, for example, two or more elastomer layers laminated in the tire radial direction, or may have a plurality of elastomer layers in the tire axial direction.

Examples of the tread rubber 2G include isoprene rubber such as natural rubber and isoprene rubber, diene rubber such as butadiene rubber, styrene butadiene rubber, styrene isoprene butadiene rubber, chloroprene rubber, acrylonitrile butadiene rubber, and butyl rubber.

The outer surface 2a of the tread portion 2 is appropriately provided with, for example, circumferential grooves 2b extending in the tire circumferential direction, lateral grooves (not shown) extending in the tire axial direction, sipes (not shown) having a groove width of 2 mm or less, and the like. may As the circumferential groove 2b, for example, a linearly extending groove or a zigzag extending groove can be used.

The profile of the outer surface 2a of the tread portion 2 is, for example, a single circular arc, a combination of circular arcs with a plurality of curvatures, or a straight line in the tire meridian cross section. The outer surface 2a of the tread portion 2 desirably defines the tire equatorial position C. As shown in FIG. Here, the tire equator position C is the center position of the tread ground contact edges Te on both sides in the tire axial direction.

Further, the tread ground contact edge Te is the outermost ground contact position in the tire axial direction when the pneumatic tire 1 in a normal state is applied with a normal load and grounds on a flat surface with a camber angle of 0°. That is, the tread width TW between the tread edges Te is the maximum width of the tread when a normal load is applied to the pneumatic tire 1 in a normal state.

Here, the "regular load" is the load determined for each tire by each standard when there is a system of standards including the standards on which the pneumatic tire 1 is based. If it is ETRTO, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", and if it is ETRTO, it is "LOAD CAPACITY". “Normal load” is a load determined for each tire by a manufacturer or the like when there is no standard system including the standard on which the pneumatic tire 1 is based.

The profile of the outer surface 3a of the sidewall portion 3 is, for example, a combination of a single circular arc, circular arcs with multiple curvatures, curved lines, or straight lines. Here, the outer surface 3a of the sidewall portion 3 is defined as not including partial irregularities that are not continuous in the tire circumferential direction, such as decorative serrations, mark display ribs, and protective protective ribs. .

The outer surface 3a of the sidewall portion 3 desirably defines the maximum width position P of the tire. Here, the tire maximum width position P is a position where the axial width W of the tire is maximized. For example, if the position where the width W in the tire axial direction is the maximum has a certain range in the tire radial direction, the tire maximum width position P is the center position in the tire radial direction of that range.

The profile of the outer surface 4a of the bead portion 4 is, for example, a combination of a single circular arc, circular arcs with multiple curvatures, curved lines, or straight lines. Here, the outer surface 3a of the sidewall portion 3 is defined as not including partial irregularities that are not continuous in the tire circumferential direction, such as decorative serrations, mark display ribs, and protective protective ribs. .

The bead portion 4 of this embodiment has a bead reinforcing layer 11 extending outward in the tire radial direction from the bead core 5 . Such a bead reinforcing layer 11 can improve the rigidity of the bead portion 4 and improve the durability performance of the pneumatic tire 1 .

FIG. 2 is an enlarged sectional view of the bead portion 4. As shown in FIG. As shown in FIGS. 1 and 2, the thickness t1 of the bead portion 4 at the center position 11c in the tire radial direction of the bead reinforcing layer 11 of this embodiment is the thickness t1 of the tread rubber 2G at the tire equator position C. greater than t2. Such bead portions 4 help improve the durability performance of the pneumatic tire 1 . Note that the time required for vulcanization molding of the pneumatic tire 1 is set based on the portion where the rubber thickness is large. It varies according to t1.

Here, the center position 11c of the bead reinforcing layer 11 is defined as the position between the outer end 11b and the inner end 11d in the tire radial direction on the outer side surface 11a of the bead reinforcing layer 11 arranged in the bead portion 4 in the tire radial direction. is the center position of That is, the tire radial length L1 from the inner end 11d of the bead reinforcing layer 11 to the central position 11c is 0.5 of the tire radial length L2 from the inner end 11d to the outer end 11b of the bead reinforcing layer 11. Double.

Further, the thickness t1 of the bead portion 4 at the central position 11c of the bead reinforcing layer 11 is the same as the thickness t1 of the inner cavity surface of the inner liner 7, which will be described later, in the direction perpendicular to the outer surface 11a of the bead reinforcing layer 11 at the central position 11c. It is the distance from 7 a to the outer surface 4 a of the bead portion 4 . As the thickness t1 of the bead portion 4 at the central position 11c of the bead reinforcing layer 11, for example, the maximum thickness of the bead portion 4 may be employed.

When the central position 11c of the bead reinforcing layer 11 is positioned at the sidewall portion 3, the thickness t1 of the bead reinforcing layer 11 at the central position 11c is the thickness of the sidewall portion 3 at the central position 11c of the bead reinforcing layer 11. thickness.

Here, in the present specification, the boundary between the sidewall portion 3 and the bead portion 4 is a position spaced 5% of the tire section height H inside the tire maximum width position P in the tire radial direction. . The tire cross-sectional height H is the distance in the tire radial direction from the bead base line BL corresponding to the rim diameter of a regular rim to the outer surface 2a of the tread portion 2 at the tire equator position C.

Further, the thickness t2 of the tread rubber 2G at the tire equator position C is the distance from the outer surface 2a of the tread portion 2 at the tire equator position C to the outer surface 10a of the band layer 10 described later. The thickness t2 of the tread rubber 2G is the distance from the outer surface 2a of the tread portion 2 to the outer surface 10a of the band layer 10 when the groove is filled in when the tread portion 2 has a groove at the tire equator position C. is.

The bead reinforcing layer 11 of this embodiment contains a metal member. In such a pneumatic tire 1, the heat generated in the bead core 5 during vulcanization molding can be conducted to the entire bead portion 4 via the metal member, and the thickness t1 of the bead portion 4 is equal to the tread rubber 2G. The vulcanization time can also be shortened when the thickness is greater than the thickness t2. Therefore, the pneumatic tire 1 of the present embodiment can be vulcanized in a short time even when the thickness t1 of the bead portion 4 is large.

As a more preferable embodiment, the thickness t1 of the bead portion 4 at the central position 11c of the bead reinforcing layer 11 is 10 mm or more. Such a bead portion 4 can reliably improve the durability performance of the pneumatic tire 1 .

As shown in FIG. 1 , the pneumatic tire 1 of this embodiment includes a toroidal carcass 6 extending between the bead cores 5 of a pair of bead portions 4 via a tread portion 2 and a pair of sidewall portions 3 and an inner tire. A liner 7 is provided. The carcass 6 includes at least one, in this embodiment two carcass plies 6A, 6B. Since such a carcass 6 has two carcass plies 6A and 6B, it has high rigidity, and the durability performance of the pneumatic tire 1 can be improved.

The carcass plies 6A and 6B of this embodiment each extend between the pair of bead portions 4 via the tread portion 2 and the pair of sidewall portions 3. As shown in FIG. The two carcass plies 6A and 6B are, for example, a first carcass ply 6A positioned inside in the tire radial direction and a second carcass ply positioned outside the first carcass ply 6A in the tire radial direction in the tread portion 2. 6B.

At least one of the carcass plies 6A and 6B includes a main body portion 6a extending from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and continuing from the main body portion 6a and around the bead core 5 in the tire axial direction. It is desirable to include a folded portion 6b that is folded back from the inside to the outside.

In this embodiment, each of the first carcass ply 6A and the second carcass ply 6B includes a main body portion 6a and a folded portion 6b. For example, a bead apex 8 extending outward in the tire radial direction from the bead core 5 is arranged between the main body portion 6a and the folded portion 6b of the carcass plies 6A, 6B.

The carcass plies 6A, 6B of the present embodiment include carcass cords (not shown) made of organic fiber cords. Organic fiber cords include, for example, cords of one or more hybrid fibers selected from the group consisting of polyethylene terephthalate fibers, polyethylene naphthalate fibers, nylon fibers, aramid fibers and rayon fibers.

The carcass cords are preferably arranged at an angle of 60-90° with respect to the tire circumferential direction. When the carcass cords are inclined at an angle of less than 90° with respect to the tire circumferential direction, the carcass cords of the first carcass ply 6A and the carcass cords of the second carcass ply 6B are inclined in opposite directions to each other with respect to the tire circumferential direction. It is desirable to Here, the carcass cord angle is the angle in the pneumatic tire 1 in a normal state, and can be confirmed by, for example, partially peeling off the tread portion 2 .

The inner liner 7 of this embodiment is arranged on the tire inner cavity side of the first carcass ply 6A and defines a tire inner cavity surface 7a. The inner liner 7 is preferably arranged adjacent to the body portion 6a of the first carcass ply 6A. Such an inner liner 7 can retain the compressed air filled in the tire cavity.

The pneumatic tire 1 of this embodiment has a belt layer 9 arranged outside the carcass 6 in the tire radial direction, and a band layer 10 arranged outside the belt layer 9 in the tire radial direction.

The belt layer 9 includes at least one, preferably two or more, two belt plies 9A and 9B in this embodiment. The two belt plies 9A and 9B include, for example, a first belt ply 9A located inside in the tire radial direction and a second belt ply 9B located outside the first belt ply 9A. Such a belt layer 9 can increase the rigidity of the tread portion 2 and improve the durability performance of the pneumatic tire 1 .

The belt plies 9A and 9B of the belt layer 9 of the present embodiment include steel belt cords (not shown) and an elastomer composition covering the belt cords. The belt cords preferably consist of steel single wires. The belt cord may be, for example, a stranded wire in which a plurality of steel filaments are twisted together.

The belt cords are arranged, for example, at an angle of 10 to 30° with respect to the tire circumferential direction. It is desirable that the belt cords of the first belt ply 9A and the belt cords of the second belt ply 9B are inclined in opposite directions to each other with respect to the tire circumferential direction. Such a belt layer 9 can increase the rigidity of the tread portion 2 in a well-balanced manner and improve the durability performance of the pneumatic tire 1 . Here, the angle of the belt cord is the angle in the pneumatic tire 1 in the normal state, and can be confirmed by partially peeling off the tread portion 2, for example.

The elastomer composition of the belt plies 9A and 9B of this embodiment exhibits rubber elasticity. Examples of elastomer compositions for the belt plies 9A and 9B include rubber compositions and thermoplastic elastomer compositions.

When the elastomer composition of the belt plies 9A and 9B is a rubber composition, examples of rubber components include isoprene-based rubber, butadiene-based rubber, styrene-butadiene rubber, nitrile rubber, and butyl rubber. When the elastomer composition of the belt plies 9A and 9B is a thermoplastic elastomer composition, examples of the elastomer include block copolymers such as thermoplastic polyurethanes, styrene-butadiene block copolymers, and styrene-ethylene-butylene-styrene block copolymers. etc.

The surface of the belt cord of this embodiment is plated or ternary plated. Plating includes, for example, copper (Cu), zinc (Zn), and the like. Examples of ternary plating include those containing copper (Cu), zinc (Zn), cobalt (Co), and the like. Such a belt cord has good adhesion to the elastomer composition, and can generate stress in cooperation with the belt cord and the elastomer composition even during high-speed running. It is possible to improve the durability performance of

The band layer 10 includes at least one band ply 10A, in this embodiment one band ply 10A, and a pair of edge bands 10B covering the axially outer side of the band ply 10A, defining a tire radially outer surface 10a. is doing. Here, the outer surface 10a of the band layer 10 is defined as the outermost surface in the tire radial direction of the band ply 10A and the edge band 10B. Such a band layer 10 is adjacent to the tread rubber 2G via the outer surface 10a.

Each of the band ply 10A and the edge band 10B of the present embodiment includes a band cord arranged at an angle of 5° or less with respect to the tire circumferential direction, and an elastomer composition covering the band cord. Here, the angle of the band cord is the angle in the pneumatic tire 1 in the normal state, and can be confirmed by partially peeling off the tread portion 2, for example.

Band cords are made of, for example, metal or organic fibers. When the band cord is metal, the band cord is preferably formed from a single steel wire or a stranded wire of a plurality of steel filaments which is plated or ternary plated on its surface. When the band cord is an organic fiber, the band cord is made of one or more hybrid fibers selected from the group consisting of polyethylene terephthalate fiber, polyethylene naphthalate fiber, nylon fiber, aramid fiber and rayon fiber. is desirable.

The elastomer composition of the band ply 10A and the edge band 10B preferably exhibits rubber elasticity like the elastomer composition of the belt plies 9A, 9B. The elastomer composition of the band ply 10A and the edge band 10B may be, for example, the same as the elastomer composition of the belt plies 9A, 9B.

The outer end 11b of the bead reinforcing layer 11 in the tire radial direction is preferably located in the sidewall portion 3 radially inward of the maximum width position P of the tire. The outer end 11b of the bead reinforcing layer 11 of this embodiment is located between the outer end 8a (shown in FIG. 2) of the bead apex 8 and the maximum width position P of the tire. Such a bead reinforcing layer 11 can conduct heat generated in the bead core 5 during vulcanization molding to the entire bead portion 4 while suppressing an increase in weight due to inclusion of a metal member.

As shown in FIG. 2 , the tire radial inner end 11 d of the bead reinforcing layer 11 of the present embodiment is located radially outside the tire radial outer end surface 5 a of the bead core 5 . Such a bead reinforcing layer 11 suppresses an increase in weight due to inclusion of a metal member, and is useful for improving the fuel efficiency performance of the pneumatic tire 1 .

A distance L3 in the tire radial direction between the inner end 11d of the bead reinforcing layer 11 and the outer end surface 5a of the bead core 5 is preferably 20 mm or less. Since the distance L3 between the bead reinforcing layer 11 and the bead core 5 is 20 mm or less, the heat generated in the bead core 5 during vulcanization is efficiently transferred to the entire bead portion 4 via the metal member of the bead reinforcing layer 11. can be conducted. From this point of view, the distance L3 between the bead reinforcing layer 11 and the bead core 5 is more preferably 5 mm or less, still more preferably 1 mm or less.

Although illustration is omitted, the inner end 11d of the bead reinforcing layer 11 may be located inside the outer end surface 5a of the bead core 5 in the tire radial direction, for example. The bead reinforcing layer 11 in this case is preferably arranged adjacent to the bead core 5 . Such a bead reinforcing layer 11 can efficiently conduct heat generated in the bead core 5 during vulcanization molding to the entire bead portion 4 .

The amount of overlap between the bead reinforcing layer 11 and the bead core 5, that is, the distance in the tire radial direction between the inner end 11d of the bead reinforcing layer 11 and the outer end surface 5a of the bead core 5 is preferably 5 mm or less. Such a bead reinforcing layer 11 suppresses an increase in weight due to inclusion of a metal member, and is useful for improving the fuel efficiency performance of the pneumatic tire 1 .

The distance L4 between the bead reinforcing layer 11 and the outer surface 4a of the bead portion 4 at the central position 11c of the bead reinforcing layer 11 is preferably equal to the thickness t1 of the bead portion 4 at the central position 11c of the bead reinforcing layer 11. 30% to 80% of In such a bead portion 4, the bead reinforcing layer 11 is arranged in the center region of the bead portion 4 in the axial direction of the tire. heat can be efficiently conducted to the entire bead portion 4.

The distance L5 between the bead reinforcing layer 11 and the outer surface 3a of the sidewall portion 3 at the position of the outer end 11b of the bead reinforcing layer 11 in the tire radial direction is the side It is 60% to 90% of the thickness t3 of the wall portion 3. The thickness t3 of the sidewall portion 3 at the position of the outer end 11b of the bead reinforcing layer 11 of this embodiment is smaller than the thickness t1 of the bead portion 4 at the central position 11c of the bead reinforcing layer 11 .

Such a bead reinforcing layer 11 can improve the durability performance of the pneumatic tire 1 without being exposed from the outer surface 3a even in the sidewall portion 3 having a small thickness t3. When the outer end 11b of the bead reinforcing layer 11 is positioned at the bead portion 4, the distance L5 is the distance between the bead reinforcing layer 11 and the outer surface 4a of the bead portion 4 at the position of the outer end 11b. A thickness t3 is the thickness of the bead portion 4 at the position of the outer end 11b.

The bead reinforcing layer 11 of this embodiment is arranged between the main body portion 6a and the folded portion 6b of the carcass plies 6A and 6B. Such a bead reinforcing layer 11 can efficiently conduct heat generated in the bead core 5 during vulcanization molding to the entire bead portion 4 via the metal member of the bead reinforcing layer 11. It helps to shorten the vulcanization time of.

The bead reinforcing layer 11 is preferably arranged adjacent to the turn-up portions 6b of the carcass plies 6A, 6B. The bead reinforcing layer 11 of this embodiment is arranged adjacent to the turn-up portion 6b of the second carcass ply 6B. Such a bead reinforcing layer 11 can reinforce the turn-up portions 6b of the carcass plies 6A and 6B, and can improve the durability performance of the pneumatic tire 1. As shown in FIG.

The metal member of the bead reinforcing layer 11 is made of copper, for example. The bead reinforcing layer 11 of this embodiment includes a plurality of copper cords and an elastomer composition covering the copper cords. The bead reinforcing layer 11 may be a thin plate made of copper, for example. Such a bead reinforcing layer 11 has excellent thermal conductivity and can shorten the vulcanization time of the pneumatic tire 1 .

The metal member of the bead reinforcing layer 11 may be made of iron, for example. The metal member of the bead reinforcing layer 11 in this case is, for example, a steel cord. The bead reinforcing layer 11 may include, for example, copper cords, steel cords, and an elastomer composition coating the copper cords and steel cords. Such a bead reinforcing layer 11 has good thermal conductivity and high strength, and can both shorten the vulcanization time of the pneumatic tire 1 and improve durability.

The bead portion 4 is provided with a chafer 12, for example. The chafer 12 is desirably arranged so as to cover the carcass plies 6A, 6B from the main body portion 6a to the folded portion 6b. Such a chafer 12 can reinforce the bead portion 4 and improve the durability performance of the pneumatic tire 1 .

Although the particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and can be implemented in various modified forms.

A pneumatic tire having the basic structure shown in FIGS. 1 and 2 was made as a trial based on the specifications in Tables 1 and 2, and the time required for vulcanization molding at the time of trial was tested. Common specifications and test methods are as follows.

<Common specifications>
Tire size: 195/65R15
Bead thickness > tread rubber thickness

<Vulcanization time>
The shortest time during vulcanization molding of a pneumatic tire was measured to prevent insufficient vulcanization. The results are expressed as an index with Comparative Example 1 being 100, and the smaller the number, the shorter the vulcanization time.

The results of the tests are shown in Tables 1 and 2.

As a result of the test, it was confirmed that the pneumatic tire of the example has a shorter vulcanization time than the comparative example, and vulcanization molding can be performed in a short time even when the thickness of the bead portion is large. .

1 pneumatic tire 2 tread portion 2G tread rubber 3 sidewall portion 4 bead portion 5 bead core 11 bead reinforcing layer 11c central position

Claims (12)

A pneumatic tire,
A tread portion having a ground contact surface, a pair of sidewall portions extending radially inward from both sides of the tread portion in the tire axial direction, and a bead portion having a bead core inside each of the sidewall portions in the tire radial direction. and
The tread portion has a tread rubber that forms the ground contact surface,
The bead portion has a bead reinforcing layer extending outward in the tire radial direction from the bead core,
The thickness of the bead portion at the center position in the tire radial direction of the bead reinforcing layer is greater than the thickness of the tread rubber at the tire equator position,
The bead reinforcing layer includes a metal member,
pneumatic tires. 2 . The pneumatic tire according to claim 1 , wherein the inner end of the bead reinforcing layer in the tire radial direction is positioned radially outward of the outer end surface of the bead core in the tire radial direction. 3. The pneumatic tire according to claim 2, wherein a distance in the tire radial direction between said inner end of said bead reinforcing layer and said outer end surface of said bead core is 20 mm or less. The pneumatic tire according to any one of claims 1 to 3, wherein the thickness of the bead portion at the center position of the bead reinforcing layer is 10 mm or more. The pneumatic tire according to any one of claims 1 to 4, wherein an outer end of the bead reinforcing layer in the tire radial direction is located in the sidewall portion radially inward of the tire maximum width position. The distance between the bead reinforcing layer and the outer surface of the sidewall portion at the position of the outer end of the bead reinforcing layer is the thickness of the sidewall portion at the position of the outer end of the bead reinforcing layer. 60% to 90% of the pneumatic tire according to claim 5. The distance between the bead reinforcing layer and the outer surface of the bead portion at the central position of the bead reinforcing layer is 30% to 80% of the thickness of the bead portion at the central position of the bead reinforcing layer. The pneumatic tire according to any one of claims 1 to 6, wherein: A carcass extending between the pair of bead portions via the tread portion and the pair of sidewall portions,
The carcass includes at least one carcass ply,
At least one of the carcass plies includes a main body portion extending from the tread portion through the sidewall portion to the bead core of the bead portion, and continuing from the main body portion and surrounding the bead core from the inner side in the tire axial direction. and a folded portion folded outwardly,
The pneumatic tire according to any one of claims 1 to 7, wherein the bead reinforcing layer is arranged between the body portion and the folded portion. The pneumatic tire according to claim 8, wherein the bead reinforcing layer is arranged adjacent to the folded portion. The pneumatic tire according to claim 8 or 9, wherein the carcass ply includes carcass cords made of organic fiber cords. 11. The pneumatic tire according to any one of claims 1 to 10, wherein said metal member is made of copper. The pneumatic tire according to any one of claims 1 to 10, wherein the metal member is a steel cord.

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