JP7211802B2 - pneumatic tire - Google Patents

Description

The present invention relates to pneumatic tires.

The pneumatic tire carcass plies disclosed in Patent Documents 1 to 3 include a first ply that is continuous between a pair of bead portions and a discontinuous second ply that is arranged outside the first ply in the tire radial direction. Prepare. The second ply includes a pair of ply pieces extending from the tread portion to either one of the pair of bead portions. In the center of the tread portion, there is provided an area where neither of the two ply pieces exists, that is, a hollow portion. The hollow portion of the second ply is intended to achieve both of two fundamentally contradictory performances. One type of performance is rigidity (which contributes to improved steering stability) and cut resistance, and the other type of performance is weight reduction and thus rolling resistance reduction.

Patent No. 6125708 Patent No. 5629356 Patent No. 5178442

The structures disclosed in Patent Literatures 1 to 3 have room for further improvement in terms of reducing weight and thereby reducing rolling resistance while ensuring rigidity and cut resistance.

SUMMARY OF THE INVENTION An object of the present invention is to reduce the weight of a pneumatic tire including a carcass ply having a hollow portion while ensuring rigidity and cut resistance, thereby reducing rolling resistance.

In one aspect of the present invention, a tread portion, a pair of sidewall portions extending inward in the tire radial direction from both ends of the tread portion, and a pair of sidewall portions disposed at the inner end portions in the tire radial direction of the pair of sidewall portions, respectively. a pair of bead cores, a central portion positioned radially inward of the tread portion, and a pair of side portions extending inward in the tire radial direction from both ends of the central portion; , a first ply having an end portion that terminates outside the bead core in the tire radial direction without being wound up by the bead core; Each has an inner end positioned at a portion, each extending continuously from the inner end to the inner side in the tire radial direction and wound up on one of the pair of bead cores to form the pair of sidewall portions. a discontinuous second ply, one of said pair of side portions of said first ply, and said pair of ply pieces each comprising a pair of ply pieces each having a turnup having an outer end terminating at either. A pneumatic tire comprising a pair of joining members that join the roll-up portion of any one of the above.

The second ply comprises a pair of ply pieces and is discontinuous. In other words, there is a hollow portion where no ply exists between the inner ends of the pair of ply pieces. By adopting the second ply having such a hollow portion, the weight can be reduced as compared with the case where the second ply is one continuous ply. Moreover, the side portion of the first ply has an end portion that terminates outside the bead core in the tire radial direction. That is, the first ply is not wound onto the bead core, and only one ply, ie, a pair of ply pieces, is wound onto each bead core. Weight reduction can also be achieved by this configuration.

The first ply is not wound up on the bead core. However, the side portions of the first ply are joined to the ply pieces forming the second ply by joining members. The ply piece (second ply) has an inner end positioned at the tread portion and a roll-up portion rolled up around the bead core. In other words, both ends of the ply pieces forming the second ply are held relatively firmly. Since the first ply is joined by the joining member to the ply pieces of the second ply whose both ends are held relatively firmly, the necessary rigidity is ensured by the cooperation of the first and second plies. . Also, by bonding to the firmly held second ply, the distortion of the first ply can be reduced.

Over the entire sidewall portion, two layers of plies are arranged, namely a side portion of a first ply and a side portion of a ply piece (second ply). In addition, in the region of the sidewall portion on the bead core side, a ply of one layer, that is, a roll-up portion of a ply piece is arranged. By providing two or three layers of plies in the sidewall portion in this manner, the required cut resistance is ensured. In addition, by providing two or three layers of plies, the required rigidity in the sidewall portion is ensured.

As described above, according to one aspect of the present invention, it is possible to reduce the weight and thereby reduce the rolling resistance while ensuring the rigidity and the resulting steering stability and cut resistance.

The tread portion further includes a belt layer disposed outside the central portion of the first ply in the tire radial direction, and the inner end portion of the ply piece is connected to the belt layer and the central portion of the first ply. may be placed between

With this configuration, the inner end of the ply piece (second ply) is firmly held by the belt layer, so that the rigidity of the second ply can be ensured more reliably.

The winding portion of the ply piece includes an inner portion arranged inward of the bead core in the tire width direction, a winding portion provided continuously with the inner portion and wound around the bead core, and the winding portion. an outer portion provided continuously with the hanging portion, disposed outside the bead core in the tire width direction and including the outer end portion, and a portion including the end portion of the side portion of the first ply; , and the inner portion of the ply piece may be joined by the joining member.

With this configuration, the first ply can be joined to the ply piece (second ply) with sufficient joining strength.

The pneumatic tire further comprises a pair of bead fillers each having a base end arranged adjacent to the outer side in the tire radial direction of one of the pair of bead cores and a tip opposite to the base end, The end portion of the side portion of the first ply may be positioned inside the tip of the bead filler in the tire radial direction and outside the base end of the bead filler in the tire radial direction. .

With this configuration, the bead filler functions to hold the end of the first ply when the pneumatic tire is mounted on the wheel, so the rigidity of the first ply can be more reliably secured.

The position of the end of the first ply is such that the amount of overlap of the side portion of the first ply with respect to the bead filler is 5 mm or more, and the end of the first ply is the base end of the bead filler. may be set to be 5 mm or more away from the

With this configuration, stress concentration can be prevented without causing an unnecessary weight increase of the first ply.

The outer end portion of the ply piece may be positioned radially outward of the tip of the bead filler and radially inward of the tread portion.

With this configuration, a sufficient area is secured in the sidewall portion where three plies exist, that is, the side portion of the first ply, the side portion of the ply piece (second ply), and the outer portion of the roll-up portion of the ply piece. be. As a result, rigidity and cut resistance can be ensured more reliably.

The outer end portion of the ply piece may be positioned radially outside the maximum width position of the sidewall portion and radially inside the tread portion.

By arranging the outer ends of the ply pieces at this position, in particular, the rigidity of the sidewall portion can be improved.

The end portion of the first ply may be positioned between an inner end portion and an outer end portion of the joining member in the tire radial direction.

With this configuration, the portion including the end portion of the first ply can be firmly joined to the second ply, and the distortion of the first ply can be reduced more effectively.

The joining member may have an adhesive strength of 500 gf or more.

The modulus of the first ply may be lower than the modulus of the pair of ply pieces of the second ply.

Carcass plies generally tend to have a lower modulus (stress generated when a certain strain is applied), a lighter weight, and a higher modulus, a heavier weight. The second ply has a hollow portion while the first ply has a central portion in the tread portion. The central portion of the first ply contributes less to the improvement of rigidity and cut resistance than the ply pieces forming the side portions of the first ply and the second ply. By making the first ply having such a central portion lower modulus and thus relatively lighter than the ply pieces of the second ply, further weight reduction can be achieved without sacrificing rigidity and cut resistance. .

The breaking strength of the first ply may be lower than the breaking strength of the pair of ply pieces of the second ply.

Carcass plies generally tend to be lighter in weight as the breaking strength (tensile load causing breakage) is lower, and heavier as the breaking strength is higher. The second ply has a hollow portion while the first ply has a central portion in the tread portion. The central portion of the first ply contributes less to the improvement of rigidity and cut resistance than the ply pieces forming the side portions of the first ply and the second ply. The first ply having such a central portion has a lower breaking strength than the ply pieces of the second ply, and is therefore relatively lightweight, thereby further reducing weight without impairing rigidity and cut resistance. can be done.

In order to make the modulus or breaking strength different, the pair of ply pieces of the first ply and the second ply have at least one of cord material, cord diameter, number of ends, rubber hardness, and rubber thickness. can be different.

Advantageous Effects of Invention According to the present invention, in a pneumatic tire including a carcass ply having a hollow portion, it is possible to reduce weight and thereby reduce rolling resistance while ensuring rigidity and cut resistance.

1 is a meridional cross-sectional view of a pneumatic tire according to an embodiment of the present invention; FIG. 1 is a meridional cross-sectional view of a tread portion of a pneumatic tire according to an embodiment of the present invention and its surroundings. FIG. 2 is an enlarged view of portion III of FIG. 1; FIG. 2 is an enlarged view of portion IV of FIG. 1;

1 to 4 show a rubber pneumatic tire (hereinafter referred to as tire) 1 according to an embodiment of the present invention.

A tire 1 includes a tread portion 2 , a pair of sidewall portions 3 , and a pair of ring-shaped bead portions 4 .

The tread portion 2 extends in the tire width direction (indicated by symbol TW in FIG. 1). Grooves 2a are provided on the surface of the tread portion 2, that is, on the tread surface.

The pair of sidewall portions 3 each extend inward in the tire radial direction (symbol TR in FIG. 1) from both ends of the tread portion 2 .

The pair of bead portions 4 are arranged at the inner end portions of the pair of sidewall portions 3 in the tire radial direction, respectively. Each bead portion 4 comprises a bead core 5 and a bead filler 6 . The bead core 5 comprises a large number of steel wires bundled into a ring. The bead filler 6 is ring-shaped and made of rubber harder than the rubber forming the tread portion 2 and the sidewall portion 3 . The bead filler 6 has a base end 6a arranged adjacent to the outer side of the bead core 5 in the tire radial direction, and a tip end 6b opposite to the base end 6a. It tapers outward. Each bead portion 4 comprises a strip rubber 7 provided so as to wrap a bead core 5 and a bead filler 6 .

The tire 1 includes a carcass 10 that is toroidally spanned between the bead portions 4 . In this embodiment, the carcass 10 includes a first carcass ply (hereinafter referred to as “first ply”) 11 and a second carcass ply (hereinafter referred to as “second ply”) 12 . The second ply 12 is a ply having a hollow portion 13b, while the first ply 11 is a normal ply having no hollow portion. The first and second plies 11, 12 will be detailed later. An inner liner 8 is provided inside the carcass 10 , that is, on the innermost peripheral surface of the tire 1 .

With reference to FIGS. 2 and 3 , an endless belt layer 20 is provided between the tread portion 2 , more specifically the carcass 10 and the tread portion 2 . In this embodiment, the belt layer 20 has two belts 21 and 22 . The belt 21 is arranged adjacent to the outer side of the carcass 10 in the tire radial direction, and the belt 22 is arranged adjacent to the outer side of the belt 21 in the tire radial direction. In addition, in the present embodiment, the dimension of the lower belt 21 in the tire width direction is larger than the dimension of the upper belt 22 in the tire width direction, and the end 21a of the belt 21 is closer to the tire than the end 22a of the belt 22. It is positioned on the outside in the width direction. The belts 21 and 22 are formed by coating steel or organic fiber belt cords with rubber. The belt layer 20 may be composed of one belt, or may be provided with three or more belts.

An endless cap layer 30 is provided adjacent to the outer side of the belt layer 20 in the tire radial direction. The cap layer 30 of this embodiment comprises a pair of narrow edge plies 31 directly covering either of the ends 21a, 22a of the belts 21, 22, respectively. In addition, the cap layer 30 of the present embodiment includes a wide cap ply 32 that is arranged adjacent to the edge ply 31 in the tire radial direction and covers the entire belts 21 and 22 including the ends 21a and 22a with one sheet. . Cap layer 30 may comprise one or more plies. Alternatively, the cap layer 30 may be omitted.

A pair of endless rubber pads 40 are arranged between the outer end portions of the belt layer 20 in the tire width direction and the carcass layer 10 . The cross-sectional shape of the pad 40 is a flat triangular shape. The positions of the ends 21a and 22a of the belts 21 and 22, the outer end 31a of the edge ply 31 in the tire width direction, and the end 32a of the cap ply 32 in the tire width direction correspond to the outer ends of the pad 40 in the tire width direction. It is set in the area between the portion 40a and the inner end portion 40b, that is, the area where the pad 40 exists. Pad 40 may be eliminated.

The first and second plies 11, 12 constituting the carcass 10 will be described below.

The first ply 11 is a single ply, while the second ply 12 is a discontinuous ply having a hollow portion 13b as described above, and is composed of a pair of ply pieces 13. As shown in FIG. As will be described later, the first ply 11 and the pair of ply pieces 13 are joined by a joining tape (joining member) 14 . Each of the ply pieces 13 of the first ply 11 and the second ply 12 is a band-shaped sheet in which a plurality of cords arranged side by side with a gap are covered with rubber.

The ply pieces 13 of the first ply 11 and the second ply 12 may have the same or different moduli (stress generated when a certain strain is applied). Further, the breaking strength (tensile load at which breakage occurs) may be the same or different between the ply pieces 13 of the first ply 11 and the second ply 12 . A case where the ply pieces 13 of the first ply 11 and the second ply 12 have different moduli and breaking strengths will be described in detail later.

The first ply 11 includes a central portion 11a located inside the tread portion 2 in the tire radial direction, and a pair of side portions 11b extending inward in the tire radial direction from both ends of the central portion 11a in the tire width direction. The side portion 11 b is arranged on the sidewall portion 3 . Each side portion 11b of the first ply 11 has an end portion 11c that terminates outside the bead core 5 in the tire radial direction. In other words, the first ply 11 is not rolled up on the bead core 5 .

In the present embodiment, the end portion 11c of the side portion 11b of the first ply 11 is located radially inside the tip 6b of the bead filler 6 and outside the base end 6a of the bead filler 6 in the tire radial direction. . That is, the side portion 11 b of the first ply 11 overlaps the bead filler 6 . Referring to FIG. 4, the position of the end portion 11c of the first ply 11 is the overlap amount R ( from the end portion 11c of the first ply 11 to the tip 6b of the bead filler 6) of the side portion 11b of the first ply 11 with respect to the bead filler 6. ) is 5 mm or more, and the separation distance S of the end portion 11c of the first ply 11 from the base end 6a of the bead filler 6 is set to be 5 mm or more.

The second ply 12 is arranged adjacent to the first ply 11 on the radially outer side of the tire, and is a discontinuous ply made up of a pair of ply pieces 13 . The ply piece 13 has an inner end portion 13a located between the belt layer 20 and the central portion 11a of the first ply 11 . A pad 40 is interposed between the inner end portion 13 a and the belt layer 20 . The position of the inner end portion 13a of the ply piece 13 in the tire width direction is located in the outer region in the tire width direction of the tread portion 2, more specifically, the end portions 21a and 22a of the belts 21 and 22 forming the belt layer 20. It is set in a region on the inner side in the tire width direction than any of them. A central area of the tread portion 2 in the tire width direction, more specifically, an area between the inner end portions 13a of the pair of ply pieces 13, is provided with a hollow portion 13b. The second ply 12 does not exist in the hollow portion 13b, and only the central portion 11a of the first ply 11 exists.

The ply piece 13 has a side portion 13c extending radially inward from the inner end portion 13a. The side portion 13c is arranged adjacent to the side portion 11b of the first ply 11 on the outside in the tire width direction.

The ply piece 13 is provided continuously with the side portion 13c and has a roll-up portion 13d rolled up from the inside to the outside of the bead core 5 in the tire width direction. The roll-up portion 13 d terminates at the sidewall portion 3 .

A roll-up portion 13d of the ply piece 13 includes an inner portion 13e arranged inside the bead portion 4, that is, the bead core 5 and the bead filler 6 in the tire width direction. Further, the roll-up portion 13d includes a winding portion 13f provided continuously with the inner portion 13e and wound around the bead core 5. As shown in FIG. Further, the roll-up portion 13d includes an outer portion 13g that is provided continuously with the winding portion 13f and arranged outside the bead portion 4 in the tire width direction. The outer portion 13g is arranged to overlap with the side portion 13c on the outside in the tire width direction. An end portion of the outer portion 13g constitutes an outer end portion 13h of the ply 13. As shown in FIG. The outer end portion 13h is located radially outside the tip 6b of the bead filler 6 and inside the tread portion 2 in the tire radial direction.

The pneumatic tire 1 includes a pair of joints for jointing one of the pair of side portions 11b of the first ply 11 and one of the winding portions 13d of the pair of ply pieces 13, more specifically, the inner portion 13e. A tape 14 is provided. As shown most clearly in FIG. 4, the splicing tape 14 joins the portion of the side portion 11b of the first ply 11 including the end portion 11c and the inner portion 13e of the roll-up portion 13d of the ply piece 13. .

The joining tape 14 is made of rubber, and preferably has an adhesive force of 500 gf or more in order to ensure the joining strength of the first ply 11 to the second ply 12 .

The tire radially outer end portion 14 a of the joining tape 14 is positioned further outside the tire radial direction than the tip 6 b of the bead filler 6 . The radially inner end portion 14 b of the joining tape 14 is positioned between the proximal end 6 a and the distal end 6 b of the bead filler 6 .

The end portion 11c of the first ply 11 is located between the inner end portion 14b and the outer end portion 14b of the splicing tape in the tire width direction.

Next, the features of the pneumatic tire of this embodiment will be described.

The second ply 12 is a discontinuous ply having a pair of ply pieces 13. Between the inner ends 13b of the pair of ply pieces 13 is a hollow portion 13b where no ply exists. By adopting the second ply 12 having such a hollow portion 13b, the weight can be reduced as compared with the case where the second ply 12 is one continuous ply. Further, the side portion 11b of the first ply 11 has an end portion 11c that terminates outside the bead core 5 in the tire radial direction. That is, the first ply 11 is not wound around the bead cores 5 , and only one ply, that is, the ply piece 13 is wound around the individual bead cores 5 . Weight reduction can also be achieved by this configuration.

The first ply 11 is not wound up on the bead core 5 . However, the side portions 13 c of the first ply 11 are joined to the ply pieces 13 forming the second ply 12 by the joining tape 14 . The ply piece 13 has an inner end portion 13a positioned between the tread portion 2 (more specifically, between the belt layer 20 and the central portion 11a of the first ply 11) and a roll-up portion 13d wound around the bead core 5. . That is, both ends of the ply pieces 13 constituting the second ply 12 are held relatively firmly. Since the first ply 11 is joined by the joining tape 14 to the ply pieces 13 of the second ply 12 whose both ends are held relatively firmly, the first and second plies 11 and 12 cooperate to The required rigidity is ensured. In addition, by bonding to the firmly held second ply 12, strain of the first ply 11 can be reduced.

Over the entire sidewall portion 3, two layers of plies, that is, the side portion 11b of the first ply and the side portion 13c of the ply piece 13 are arranged. Further, in the region of the sidewall portion 3 on the side of the bead core, a single layer of ply, that is, the roll-up portion 13d of the ply piece 13 is arranged. By providing two or three layers of plies in the sidewall portion 3 in this manner, the required cut resistance is ensured. In addition, by providing two or three layers of plies, the required rigidity in the sidewall portion is ensured.

As described above, according to the present embodiment, it is possible to reduce the weight and thereby reduce the rolling resistance while ensuring rigidity, steering stability and cut resistance.

As described above, the inner end portion 13a of the ply piece 13 is positioned between the belt layer 20 and the central portion 11a of the first ply 11 . With this configuration, the inner ends 13a of the ply pieces 13 are firmly held by the belt layer 20, so that the rigidity of the second ply can be ensured more reliably.

As described above, the portion including the end portion 11c of the side portion 11b of the first ply 11 and the inner portion 13e of the winding portion 13d of the ply piece 13 are joined by the joining tape 14. As shown in FIG. With this configuration, the first ply 11 can be joined to the ply pieces 13 with sufficient joining strength.

As described above, the end portion 11c of the side portion 11b of the first ply 11 is located radially inside the tip 6b of the bead filler 6 and outside the base end 6a of the bead filler 6 in the tire radial direction. . That is, the side portion 11 b of the first ply 11 overlaps the bead filler 6 . With this configuration, the bead filler 6 functions to hold the end portion 11c of the first ply 11 when the pneumatic tire 1 is mounted on the wheel, so that the rigidity of the first ply 11 can be more reliably secured. .

As described above, the position of the end portion 11c of the first ply 11 is such that the overlapping amount R of the side portion 11b of the first ply 11 with respect to the bead filler 6 is 5 mm or more, and the end portion 11c of the first ply 11 is located above the bead filler. The distance S from the base end 6a of 6 is set to be 5 mm or more. When the overlap amount R is less than the distance R of 5 mm, the distance from the end 11c of the side portion 11b of the first ply 11 to the tip 6b of the bead filler 6 is small, so that the end of the side portion 11b of the first ply 11 Stress concentration is likely to occur at the portion 11 c or the tip 6 b of the bead filler 6 . On the other hand, if the portion of the side portion 11b of the first ply 11 that overlaps the bead filler 6 is set excessively long, the degree of contribution to the improvement in rigidity and cut resistance is low. Further, in this case, since the distance from the end portion 11c of the first ply 11 to the base end 6a of the bead filler 6 is small, stress concentration at the end portion 11c of the first ply 11 or the base end 6a of the bead filler 6 is reduced. likely to occur. On the other hand, by setting the position of the end portion 11c of the first ply as described above, stress concentration can be prevented without causing an unnecessary increase in the weight of the first ply 11. FIG.

As described above, the outer end portion 13h of the ply piece 13 is located radially outside the tip 6b of the bead filler 6 and inside the tread portion 2 in the tire radial direction. With this configuration, the sidewall portion 3 has three layers of plies, that is, the region where the side portion 11b of the first ply, the side portion 13c of the ply piece 13, and the outer portion 13g of the roll-up portion 13d of the ply piece 13 exist. Secured. As a result, rigidity and cut resistance can be ensured more reliably.

The outer end portion 13h of the ply piece 13 may be positioned radially outward of the maximum width position 3a of the sidewall portion 3 and radially inward of the tread portion 2 . Arranging the outer end portion 13h of the ply piece 13 at this position can particularly improve the rigidity of the sidewall portion 3 .

As described above, the end portion 11c of the first ply 11 is located between the inner end portion 14a and the outer end portion 14b of the joining tape 14 in the tire width direction. With this configuration, the portion including the end portion 11c of the first ply 11 is firmly joined to the second ply 12, and the distortion of the first ply 11 can be reduced more effectively.

Next, a case where the modulus and breaking strength of the ply pieces 13 of the first ply 11 and the ply pieces 13 of the second ply 12 are made different will be described.

The modulus of the first ply 11 may be lower than the modulus of the ply pieces 13 of the second ply 12 . In carcass plies, generally, the lower the modulus, the lighter the weight, and the higher the modulus, the heavier the weight. The second ply 12 has a hollow portion 13b, while the first ply 11 has a central portion 11a in the tread portion 2. As shown in FIG. Compared to the side portions 11b of the first ply 11 and the ply pieces 13 of the second ply 12, the central portion 11a of the first ply 11 contributes less to improving rigidity and cutting resistance. By making the first ply 11 having such a central portion 11a lower in modulus than the ply pieces 13 of the second ply 12, and therefore relatively light, further weight reduction can be achieved without impairing rigidity and cut resistance. can be planned.

The breaking strength of the first ply 11 may be lower than the breaking strength of the ply pieces 13 of the second ply 12 . In carcass plies, generally, the lower the breaking strength, the lighter the weight, and the higher the breaking strength, the heavier the weight. The second ply 12 has a hollow portion 13b, while the first ply 11 has a central portion 11a in the tread portion 2. As shown in FIG. Compared to the side portions 11b of the first ply 11 and the ply pieces 13 of the second ply 12, the central portion 11a of the first ply 11 contributes less to improving rigidity and cutting resistance. By making the first ply 11 having such a central portion 11a lower in breaking strength and therefore relatively lighter than the ply pieces 13 of the second ply 12, the weight is further reduced without impairing rigidity and cut resistance. can be improved.

By varying at least one of cord material, cord diameter, number of ends, rubber hardness, and rubber thickness, the modulus of the first ply 11 is set lower than the modulus of the ply pieces 13 of the second ply 12. Alternatively, the breaking strength of the first ply 11 can be set lower than the breaking strength of the ply pieces 13 of the second ply 12 .

The cord diameter, number of ends, rubber hardness, and rubber thickness generally have the following tendencies. First, the thicker the cord diameter, the higher the modulus and breaking strength. Also, the greater the number of ends, the higher the modulus and breaking strength. Furthermore, the higher the rubber hardness, the higher the modulus and breaking strength. Furthermore, the thicker the rubber, the higher the modulus and breaking strength.

As for cord materials, metal (steel), aramid, rayon, polyester, and nylon have the highest modulus in that order. Regarding cord materials, metal (steel), aramid, nylon, polyester, and rayon have the highest breaking strength in that order.

The present invention is not limited to the embodiments, and various modifications are possible. For example, in addition to the first ply 11 and the second ply 12, the pneumatic tire 1 may further include a ply having a hollow portion similar to the second ply 12 or a normal ply similar to the first ply 11. . In addition, there may be a plurality of joining tapes (joining members) for joining the individual side portions 11b of the first ply 11 to the ply pieces 13 of the second ply 12 .

REFERENCE SIGNS LIST 1 pneumatic tire 2 tread portion 2a groove 3 sidewall portion 3a maximum width position 4 bead portion 5 bead core 6 bead filler 6a base end 6b tip 7 strip rubber 8 inner liner 10 carcass 11 first carcass ply (first ply)
11a central portion 11b side portion 11c end portion 12 second carcass ply (second ply)
13 ply piece 13a inner end portion 13b hollow portion 13c side portion 13d winding portion 13e inner portion 13f winding portion 13g outer portion 13h outer end portion 14 joining tape (joining member)
14a, 14b end 20 belt layer 21 belt 21a end 22 belt 22a end 30 cap layer 31 edge ply 31a end 32 cap ply 32a end 40 pad 40a end 40b end

Claims (11)

a tread portion;
a pair of sidewall portions extending radially inward from both ends of the tread portion;
a pair of bead cores respectively arranged at the tire radial direction inner end portions of the pair of sidewall portions;
A central portion positioned radially inward of the tread portion and a pair of side portions extending inward in the tire radial direction from both ends of the central portion are provided, and the individual side portions are wound up around the bead core. a first ply having an end portion terminating outside the bead core in the tire radial direction;
Arranged radially outward with respect to the first ply, each having an inner end positioned at the tread portion in the tire width direction, and extending continuously from the inner end to the tire radially inner side. a discontinuous second ply comprising a pair of discontinuous ply pieces each having a wound portion wound on one of a pair of bead cores and having an outer end portion terminating in one of said pair of sidewall portions;
A pneumatic tire, comprising: a pair of joining members for joining one of the pair of side portions of the first ply and the winding portion of one of the pair of ply pieces, respectively. Further comprising a belt layer disposed radially outward of the central portion of the first ply in the tread portion,
2. The pneumatic tire of claim 1, wherein the inner ends of the ply pieces are positioned between the belt layer and the central portion of the first ply. The roll-up portion of the ply piece is
an inner portion arranged inside the tire width direction from the bead core;
a winding portion provided continuously with the inner portion and wound around the bead core;
an outer portion provided continuously with the winding portion, disposed outside the bead core in the tire width direction, and including the outer end portion;
The pneumatic tire according to claim 1 or 2, wherein the portion including the end portion of the side portion of the first ply and the inner portion of the ply piece are joined by the joining member. Further comprising a pair of bead fillers each having a base end arranged adjacent to the outer side in the tire radial direction of the pair of bead cores and a tip opposite to the base end,
3. The end portion of the side portion of the first ply is located inside the tip of the bead filler in the tire radial direction and outside the base end of the bead filler in the tire radial direction. 4. The pneumatic tire according to any one of 1 to 3. 5. The pneumatic tire according to claim 4 , wherein the outer end portion of the ply piece is located radially outward of the tip of the bead filler and radially inward of the tread portion. . 6. The pneumatic tire according to claim 5 , wherein the outer end portion of the ply piece is positioned radially outside the maximum width position of the sidewall portion and radially inside the tread portion. entered tire. The pneumatic according to any one of claims 1 to 6 , wherein the end of the first ply is positioned between an inner end and an outer end of the joining member in the tire radial direction. tire. The pneumatic tire according to any one of claims 1 to 7 , wherein the joining member has an adhesive strength of 500 gf or more. 9. The pneumatic tire of any preceding claim, wherein the modulus of the first ply is lower than the modulus of the pair of ply pieces of the second ply. The pneumatic tire according to any one of claims 1 to 8 , wherein the breaking strength of the first ply is lower than the breaking strength of the pair of ply pieces of the second ply. 11. The first ply and the pair of ply pieces of the second ply according to claim 9 or 10 , wherein at least one of cord material, cord diameter, number of ends, rubber hardness, and rubber thickness is different. pneumatic tires.

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