WO2022270069A1

WO2022270069A1 - Pneumatic tire

Info

Publication number: WO2022270069A1
Application number: PCT/JP2022/013250
Authority: WO
Inventors: 遥鈴木; 勲桑山
Original assignee: 株式会社ブリヂストン
Priority date: 2021-06-21
Filing date: 2022-03-22
Publication date: 2022-12-29
Also published as: JP2023001549A

Abstract

A pneumatic tire (10, 10A) has a reinforcing belt (70) that extends along the tire width direction and the tire radial direction between a belt layer (60) and a tread (41) and covers a plurality of reinforcing cords (70a) disposed at a prescribed distance from each other. In a tire cross section of the tire radial direction and tire width direction, a tire-width direction end (611) on an outer side, which is the outer side (OUT) during installation on a vehicle, of at least one belt (61) included in the belt layer (60), is positioned further inward in the tire radial direction than an end (613) on an inner side, which is the inner side (IN) during installation on a vehicle, and the width (L611) from the tire center line plane (CL) to the end (611) on the outer side is wider than the width (L613) from the tire center line plane (CL) to the end (613) on the inner side.

Description

pneumatic tire

The present invention relates to a pneumatic tire provided with a reinforcing belt positioned between the belt layer and the tread in the tire radial direction.

As a conventional pneumatic tire, a carcass layer extending in a substantially annular shape in which both ends in the tire width direction are folded back around a pair of bead cores and respectively moored, and two sheets arranged outside the carcass layer in the tire radial direction A protection consisting of a belt layer composed of belt plies, a belt reinforcing layer having embedded reinforcing elements extending substantially parallel to the tire equatorial plane arranged radially outside the belt layer and extending substantially parallel to the tire equatorial plane, and a protection ply having reinforcing cords embedded therein. A pneumatic tire having layers is known (see, for example, Patent Document 1).

According to such a conventional pneumatic tire, it is possible to suppress the expansion of the tread portion of the tire in the tire radial direction due to the centrifugal force during high-speed running, thereby improving durability performance and steering stability performance for high-speed running. It is said that

Patent No. 5084834

However, during high-speed turning, a large load is applied to the tires mounted on the outer wheels in the turning radial direction. In a conventional pneumatic tire, when the tire is deformed by this load, there is a possibility that the edge of the belt layer may touch the road surface to the outside in the tire width direction. When the tire width direction outer side of the edge of the belt layer touches the ground, there is a possibility that lateral force loss may occur due to effects such as an excessive increase in contact length in the vicinity of the contact edge.

SUMMARY OF THE INVENTION An object of the present invention is to provide a tire capable of reducing lateral force loss and improving cornering performance (improving longitudinal force) even when the tire is mounted on the outer side in the turning radial direction and performing high-speed cornering. and

A pneumatic tire according to one embodiment of the present invention includes a tread in contact with a road surface, a belt layer having a plurality of belts provided inside the tread in the tire radial direction, and provided inside the belt layer in the tire radial direction, and an annular carcass layer forming the skeleton of the tire. The pneumatic tire has, between the belt layer and the tread, a reinforcing belt covered with a plurality of reinforcing cords extending along the tire width direction and the tire radial direction and arranged at predetermined intervals. In the tire cross section along the tire radial direction and the tire width direction, the outer end portion of at least one belt included in the belt layer in the tire width direction, which is the outer side when mounted on the vehicle, is the inner side when mounted on the vehicle. It is positioned radially inward of the end portion. In the tire width direction, the width from the tire equatorial plane to the outer edge is wider than the width from the tire equatorial plane to the inner edge.

In the above configuration, the pneumatic tire includes the reinforcing belt, and the outer end portion of at least one belt included in the belt layer that is on the outer side when mounted on the vehicle in the tire width direction is the inner end portion that is on the inner side when mounted on the vehicle. located radially inward of the The width in the tire width direction from the tire equatorial plane to the outer end is wider than the width in the tire width direction from the tire equatorial plane to the inner end. Therefore, it is possible to provide a tire that can reduce lateral force loss and improve turning performance (longitudinal force can be improved) even when the tire is mounted on the outer side in the turning radial direction and performs high-speed turning.

FIG. 1 is a cross-sectional view along the tire radial direction and the tire width direction of the pneumatic tire according to the embodiment. FIG. 2 is a partially broken plan view of the tread portion. FIG. 3 is an explanatory diagram showing a usage state of the pneumatic tire according to the embodiment. FIG. 4 is a cross-sectional view of a pneumatic tire 10A according to Modification 1 along the tire radial direction and the tire width direction. FIG. 5 is a cross-sectional view of a pneumatic tire 10B according to Modification 2 along the tire radial direction and the tire width direction. FIG. 6 is a partial plan development view of the tread of a pneumatic tire 10B according to Modification 2. As shown in FIG.

Hereinafter, embodiments will be described based on the drawings. The same or similar reference numerals are given to the same functions and configurations, and the description thereof will be omitted as appropriate.

(1) Schematic Configuration of Entire Pneumatic Tire FIG. 1 is a cross-sectional view along the tire radial direction and the tire width direction of a pneumatic tire 10 according to an embodiment. FIG. 2 is a partially broken plan view of the tread portion 40. FIG.

The pneumatic tire 10 of this embodiment shown in FIGS. 1 and 2 is a pneumatic tire mounted on high-performance passenger cars, trucks, buses, and the like. The pneumatic tire 10 is mainly in contact with a pair of bead portions 20 in which bead cores 21 are respectively embedded, sidewall portions 30 extending substantially outward in the tire radial direction from each of the pair of bead portions 20, and a road surface GND. A substantially cylindrical tread portion 40 that connects the outer ends of the sidewall portions 30 in the tire radial direction.

The pneumatic tire 10 has a carcass layer 50 that extends in a substantially annular shape (toroidal shape) between the bead cores 21 to reinforce the sidewall portion 30 and the tread portion 40 to form the frame of the tire. Both ends of the carcass layer 50 in the width direction are tethered to the pair of bead cores 21 by folding back around the bead cores 21 from the inside toward the outside.

(2) Specific Configuration of Each Layer Constituting Tire The carcass layer 50 is composed of at least one sheet. In this embodiment, as shown in FIG. 2, it is composed of two carcass plies 51 . In each carcass ply 51, a large number of parallel straight carcass cords 51a are embedded. The carcass cords 51a are arranged so as to extend at 90 degrees with respect to the tire equatorial plane CL, that is, in the radial direction (meridian direction). The carcass layer 50 may be a laminate of carcass plies 51 having carcass cords 51a embedded so that the angle between the tire equatorial plane CL and the tire equatorial plane CL is 45 degrees or more and less than 90 degrees. The embedded carcass cords 51a and the carcass cords 51a embedded in other carcass plies 51 may intersect when viewed from the tread surface.

The carcass cords 51a may be made of nylon, aromatic polyamide, steel, or the like. In this embodiment, the carcass cords 51a are made of nylon.

A belt layer 60 having a plurality of

belts

61 and 63 is arranged outside the carcass layer 50 in the tire radial direction. The belt layer 60 includes at least two

inclined belts

61 and 63 laminated on the outer side in the tire radial direction. A large number of

parallel belt cords

61a, 63a extending linearly are embedded in each of the

inclined belts

61, 63. As shown in FIG. That is, the

belt cords

61a and 63a constitute the

inclined belts

61 and 63 while being covered with the

coating rubbers

61b and 63b.

The material of the

belt cords

61a and 63a is also not particularly limited, and may be composed of, for example, cords twisted from steel, aromatic polyamide, or the like, or monofilaments. The belt cord 61a of the inclined belt 61 and the belt cord 63a of the inclined belt 63 are arranged so that at least two

belt plies

61 and 63 are inclined with respect to the tire width direction (or the tire circumferential direction). The belt cords 63a intersect each other by being inclined in the opposite direction to the tire width direction. That is, the

inclined belts

61 and 63 included in the belt layer 60 are so-called intersecting belts.

In this embodiment, the belt layer 60 further includes a circumferential belt 65 in which a belt cord 65a extending substantially parallel to the tire equatorial plane CL is covered with a coating rubber 65b. The circumferential belt 65 is composed of belt cords 65a composed of twisted cords of steel or organic fibers (eg nylon, aromatic polyamide). Although the material of the belt cord 65a and the material of the

belt cords

61a and 63a may be the same, considering the performance required of the pneumatic tire 10, they are preferably different. Specifically, the belt cord 65a preferably has higher strength than the

belt cords

61a and 63a.

The number of belt cords 65a driven in the tire width direction (which may also be called an arrangement interval or arrangement density) is preferably 6 cords/cm or more.

The circumferential belt 65 is provided outside the

inclined belts

61 and 63 in the tire radial direction. In this embodiment, the circumferential belt 65 is positioned at the tire radial direction outer end of the belt layer 60 . The circumferential belt 65 is a belt reinforcing layer that is arranged so as to overlap the

inclined belts

61 and 63 and effectively suppresses the radial growth of the tread portion 40 . As shown in FIG. 2, the circumferential belt 65 is wider than the

inclined belts

61 and 63 in the tire width direction, so that the

inclined belts

61 and 63 overlap over the entire width. Note that the width of the circumferential belt 65 is in the range of 90% to 110% of the tread width.

The circumferential belt 65 can be easily formed as a so-called spiral belt, for example, by arranging one or a few belt cords 65a and covering them with rubber to form a strip having a constant width spirally wound around the

inclined belts

61 and 63 on the outside in the tire radial direction. can be molded.

The tread 41 of the tread portion 40 is a portion that comes into contact with the road surface, and is made of rubber arranged outside the circumferential belt 65 in the tire radial direction. Although not shown in the present embodiment, the outer surface (tread surface) of the tread 41 may be formed with a plurality of wide main grooves extending continuously in the circumferential direction in order to improve drainage performance. Also, a large number of lateral grooves extending in the tire width direction or oblique direction may be formed on the outer surface of the tread 41 . In the case of racing tires, the main grooves and lateral grooves may not be formed.

The belt layer 60 is provided inside the tread 41 in the tire radial direction, and a reinforcing belt 70 is arranged between the tread 41 and the belt layer 60 . Specifically, the reinforcing belt 70 is provided between the inclined belt 63 and the tread 41 (specifically, the tread rubber forming the tread 41). In this embodiment, the reinforcing belt 70 is arranged between the tread 41 and the circumferential belt 65 .

The reinforcement belt 70 is a belt in which a plurality of reinforcement cords 70a extending along the tire width direction and the tire radial direction are arranged. The reinforcing belt 70 is formed by coating a plurality of reinforcing cords 70a extending in the tire width direction and the tire radial direction and arranged at predetermined intervals in the tire circumferential direction with a coating rubber 70b.

The reinforcement cords 70a extend in the tire width direction when viewed from the tread surface, and extend along the tire radial direction (which may also be called the radial direction) when viewed from the side of the tire. Therefore, the reinforcing belt 70 may be called a radial belt or the like having cords extending along the radial direction.

The reinforcing belt 70 can be interpreted as a type of reinforcing belt that is relatively freely stretched and deformed in the tire circumferential direction, and is difficult to stretch and deform in the tire width direction. In this way, the reinforcing belt 70 can function as a component that imparts anisotropy inside the tread 41 (inward in the tire radial direction).

Further, the reinforcing belt 70 is provided between the circumferential belt 65 and the tread 41 and has the characteristics described above, so it may be called a floating belt or the like.

The thickness of the rubber layer disposed between the reinforcing cords 70a of the reinforcing belt 70 and the belt cords 65a positioned at the tire radial direction outer end of the belt layer 60 is in the range of 0.3 mm or more and 1.5 mm or less. It's okay.

The reinforcement belt 70 is provided from the outer side (OUT side) when mounted on the vehicle to the inner side (IN side) when mounted on the vehicle. Specifically, the reinforcing belt 70 may be provided on the OUT side and the IN side with respect to the tire equatorial plane CL.

Also, the reinforcing belt 70 may be provided at least up to the ground contact end in the tire width direction. The ground contact edge may be based on a state in which a normal load is applied to the pneumatic tire 10 set to a normal internal pressure. The end of the reinforcing belt 70 in the tire width direction may be located on the shoulder side of the tread 41 beyond the ground contact edge.

Here, the normal internal pressure is the air pressure corresponding to the maximum load capacity in the YearBook of JATMA (Japan Automobile Tire Manufacturers Association) in Japan, and the normal load is the maximum load corresponding to the maximum load capacity (load index) in the JATMA YearBook. capacity (maximum load). In addition, ETRTO in Europe, TRA in the United States, and tire standards in other countries are compatible.

In this embodiment, the reinforcing cords 70a embedded in the reinforcing belt 70 are preferably arranged parallel to the tire width direction, that is, arranged so that the angle formed with the tire width direction is 0 degree. However, it may have a slight angle with respect to the tire width direction. Specifically, the reinforcement cords 70a may be embedded in the reinforcement belt 70 so that the angle with respect to the tire width direction is 0 degrees or more and 15 degrees or less.

As the cord material for the reinforcing cords 70a of the reinforcing belt 70, it is desirable to use organic fibers with relatively high strength. For example, aramid fibers, specifically Kevlar (registered trademark), etc. can be used. Although nylon, polyethylene terephthalate (PET), etc. may be used depending on the use environment, it is preferable to use higher-strength organic fibers (aromatic polyamide).

The reinforcing cords 70a may be formed by twisting a plurality of the above-described organic fibers or the like, and the thickness of the reinforcing cords 70a is preferably 0.5 mm to 2.0 mm, and the Young's modulus of the reinforcing cords 70a is , 50 GPa or more.

The number of reinforcement cords 70a embedded in the reinforcement belt 70 can be, for example, in the range of 20 to 60 cords/50 mm. However, the number of reinforcement cords 70a driven into the reinforcement belt 70 is not limited to this range.

In the pneumatic tire 10 of the present embodiment, as shown in FIG. 1, the belt layer 60 is arranged asymmetrically with respect to the tire equatorial plane CL in cross sections along the tire radial direction and the tire width direction.

Specifically, as shown in FIG. 1, at least one belt included in the belt layer 60, which is the outer side OUT when mounted on the vehicle in the tire width direction, for example, the outer end 611 of the inclined belt 61 is positioned on the inner side IN when mounted on the vehicle. It is located inside the inner end portion 613 in the tire radial direction. Furthermore, a width L611 in the tire width direction from the tire equatorial plane CL to the outer end 611 is wider than a width L613 in the tire width direction from the tire equatorial plane CL to the inner end 613 . That is, the relational expression of L611>L613 is satisfied.

In this embodiment, the outer end 611 of the inclined belt 61 extends to the outer side in the tire width direction (that is, the outer side OUT when mounted on the vehicle) from the ground contact end of the pneumatic tire 10 .

Further, in this embodiment, all the belts included in the belt layer 60, that is, the inclined belts 63 and the circumferential belts 65 are also arranged asymmetrically with respect to the tire equatorial plane CL. The positions of the outer ends 631, 651 and the inner ends 633, 653 of the inclined belt 63 and the circumferential belt 65 satisfy the same conditions as the positions of the outer end 611 and the inner end 613 of the inclined belt 61. there is

Specifically, the

outer end portions

631 and 651 of the inclined belt 63 and the circumferential belt 65, which become the outer OUT when mounted on the vehicle, are positioned radially inward of the

inner end portions

633 and 653 which become the inner IN when mounted on the vehicle. ing. Furthermore, the width in the tire width direction from the tire equatorial plane CL to the outer ends 631 and 651 is wider than the width in the tire width direction from the tire equatorial plane CL to the inner ends 633 and 653 .

As shown in FIG. 1, the reinforcing belt 70 is arranged asymmetrically with respect to the tire equatorial plane CL in cross sections along the tire radial direction and the tire width direction.

Specifically, as shown in FIG. 1, the outer end (first end) 701 of the reinforcing belt 70, which is the outer OUT when mounted on the vehicle in the tire width direction, is the inner end (first end) which is the inner IN when mounted on the vehicle. 703 in the tire radial direction. Furthermore, a width L701 in the tire width direction from the tire equatorial plane CL to the outer end portion 701 is wider than a width L703 in the tire width direction from the tire equatorial plane CL to the inner end portion 703 . That is, the relational expression of L701>L703 is satisfied.

In this embodiment, the outer end 701 of the reinforcing belt 70 extends to the outer side in the tire width direction (that is, the outer side OUT when mounted on the vehicle) from the ground contact end of the pneumatic tire 10 .

(action/effect)
FIG. 3 is an explanatory diagram showing the usage state of the pneumatic tire 10 according to the embodiment. Specifically, FIG. 3 shows the state of use of a pneumatic tire 10 (hereinafter referred to as an outer wheel tire) attached to the rim RM of a wheel positioned on the outside in the turning radius direction during high-speed turning of a four-wheeled vehicle. ing. In FIG. 3, an arrow CF indicates the direction of lateral force during turning.

During high-speed turning, a large load is applied to the tires attached to the wheels. In particular, a larger load is applied to the tire mounted on the outer wheel in the turning radial direction than the tire mounted on the inner wheel in the turning radial direction. For this reason, in the conventional pneumatic tire, when the tire is deformed by this load, there is a possibility that the edge of the belt layer on the outer side in the tire width direction of the ground contact surface touches the road surface GND.

When such a situation occurs, in the conventional pneumatic tire, since the rubber layer of the tire near the ground contact position GE is not supported by the belt layer 60 from the inner side in the tire radial direction, the ground contact length becomes excessive near the ground contact end of the tire. increased, resulting in a large lateral force loss.

On the other hand, in the pneumatic tire 10 of the present embodiment, as shown in FIG. 1, at least one belt included in the belt layer 60, which is the outer side OUT when mounted on the vehicle in the tire width direction, for example, the outer side of the inclined belt 61 The end portion 611 is positioned inside in the tire radial direction of the inner end portion 613 which is the inner side IN when mounted on the vehicle. Furthermore, a width L611 in the tire width direction from the tire equatorial plane CL to the outer end 611 is wider than a width L613 in the tire width direction from the tire equatorial plane CL to the inner end 613 .

In this configuration, the outer end portion 611 of the belt layer 60 (at least the inclined belt 61) extends to the outer side in the tire width direction (that is, the outer side OUT when mounted on the vehicle) from the ground contact end of the pneumatic tire 10, and the outer end portion A sufficient thickness of the rubber layer is secured from 611 to the tire surface. Therefore, even when the tire touches the ground to the ground contact position GE which is outside the ground contact edge when mounted on the vehicle, the rubber layer near the ground contact position GE is pushed from the inner side in the tire radial direction by the belt layer 60 as shown in FIG. Supported. As a result, in the pneumatic tire 10, an excessive increase in contact length, which causes a large lateral force loss, is effectively suppressed in the vicinity of the contact position GE.

However, in a state where the rubber layer is supported from the tire radially inner side near the ground contact position GE by the belt layer 60 as shown in FIG. Power loss may occur.

Specifically, when the tread portion 40 contacts the road surface GND, the curved tire surface deforms into a planar contact surface. Along with this, in the pneumatic tire 10 of the present embodiment, the vicinity of the

ends

611, 631, 651 of the belt layer 60 extending to the tire width direction outside and the tire radial direction inside and located on the tire radial direction outside is the ground contact surface GND. (the belt layer 60 approaches a state parallel to the ground contact surface GND) in the tire radial direction. As a result, the

belt cords

61a, 63a, 65a included in the belt layer 60 are subjected to high tension in the tire circumferential direction. Therefore, the rigidity of the vicinity of the

ends

611, 631, 651 of the belt layer 60 increases in the contact state, and the contact pressure may increase in the vicinity of the contact position GE.

In addition, in the tread portion 40, an in-plane contraction force toward the center in the tire width direction acts upon contact with the road surface GND, and the tread 41 undergoes deformation called wiping deformation along the tire width direction. The wiping deformation occurs over the entire ground-contacting surface, but is particularly large in the shoulder region positioned on the outside in the tire width direction near the contact edge. Therefore, especially in the vicinity of the ground contact position GE, the tread rubber may flow toward the center in the tire width direction due to wiping deformation, further increasing the contact pressure.

In this way, there is a risk that the contact pressure will locally increase in the vicinity of the ground contact position GE due to the increased rigidity in the vicinity of the

ends

611, 631, 651 of the belt layer 60 and the wiping deformation. When such an increase in contact pressure occurs, the rubber layer in the vicinity of the contact point GE may be deformed not only in the tire circumferential direction but also in the tire width direction, increasing the lateral force loss.

The pneumatic tire 10 of this embodiment includes a reinforcing belt 70 which is arranged between the tread 41 and the belt layer 60 and in which reinforcing cords 70a extending substantially in the radial direction are embedded. Since the reinforcing belt 70 has only cords arranged along the tire width direction, it can be stretched and deformed relatively freely in the tire circumferential direction, and conversely, it has the characteristic of being difficult to deform in the tire width direction. .

The reinforcement cords 70a of the reinforcement belt 70 generate tension in the tire width direction while the pneumatic tire 10 is under ground pressure. According to the reinforcing belt 70 configured as described above, even if the compressive stress in the tire radial direction increases in the tread portion 40 due to the ground contact pressure or the air pressure of the tire, the reinforcing belt 70 disperses the influence of the compressive stress in the tire width direction. Thus, the circumferential tension applied to the

belt cords

61a, 63a, 65a of the belt layer 60 can be reduced. As a result, the rigidity in the vicinity of the

ends

611, 631, 651 of the belt layer 60 can be optimized in the grounded state.

Further, when the reinforcing cords 70a having a Young's modulus of 50 GPa or more are used as the reinforcing cords 70a, the rigidity of the reinforcing belt 70 is ensured by the reinforcing cords 70a, and the flow of the tread rubber toward the center in the tire width direction due to wiping deformation is reduced. can do. At this time, the effect of optimizing the rigidity in the vicinity of the

ends

611, 631, and 651 of the belt layer 60 by suppressing wiping deformation is greater than the effect of the rigidity of the reinforcing belt 70. The rigidity in the vicinity of the

ends

611, 631, 651 of the belt layer 60 is further optimized, and the effect of suppressing local increases in contact pressure in the vicinity of the

ends

611, 631, 651 of the belt layer 60 is further enhanced.

Therefore, even when a large load is applied to the tire mounted on the wheel during high-speed turning, a pneumatic tire 10 capable of reducing lateral force loss and improving turning performance (improving longitudinal force) is provided. be able to.

In the pneumatic tire 10 of the present embodiment, as shown in FIG. 1, the outer end portion 701 of the reinforcement belt 70 on the outer side OUT when mounted on the vehicle is positioned further in the tire radial direction than the inner end portion 703 on the inner side IN when mounted on the vehicle. located inside. Furthermore, a width L701 in the tire width direction from the tire equatorial plane CL to the outer end portion 701 is wider than a width L703 in the tire width direction from the tire equatorial plane CL to the inner end portion 703 .

In this configuration, the outer end 701 of the reinforcing belt 70 extends to the outer side in the tire width direction (that is, the outer side OUT when mounted on the vehicle) from the ground contact end of the pneumatic tire 10 . A sufficient thickness of the rubber layer is ensured from the outer edge 701 to the tire surface. Furthermore, between the ends of the reinforcing belt 70 and the belt layer 60, that is, between the outer end 701 and the outer end 651, the thickness of the rubber layer is ensured by the

coating rubbers

70b, 65b and the like.

Therefore, even if the tire touches the ground up to the ground contact position GE, which is outside the ground contact edge when mounted on the vehicle, the rubber layer of the tire in the vicinity of the ground contact position GE is supported by the reinforcing belt 70 in the tire radial direction, as shown in FIG. supported from the inside. According to this configuration, wiping deformation is effectively suppressed by the reinforcement cords 70a in the vicinity of the ground contact position GE where wiping deformation is likely to occur. Directional tension is effectively reduced.

As a result, even if a large load is applied to the tires mounted on the wheels during high-speed cornering, lateral force loss is further reduced and cornering performance is further improved.

Further, in the present embodiment, the

belt cords

61a, 63a in the

inclined belts

61, 63 have an inclination angle of 45 degrees or more and less than 90 degrees with respect to the tire equatorial plane CL. By setting the cord angle within this range, the shear strain in the circumferential direction that occurs between the road surface GND and the outermost inclined belt 63 is alleviated, suppressing the slip acting there and suppressing the tangential force in the tread width direction. can be made uniform and traction can be improved.

Also, in the present embodiment, the width of the circumferential belt 65 is within the range of 90% to 110% of the tread width. According to this configuration, the durability of the circumferential belt 65 at the tire width direction

outer end portions

651 and 653 is improved, and the radial growth of the tread portion 40 can be effectively suppressed.

(Change example)
Although the embodiment has been described above, it is obvious to those skilled in the art that the present invention is not limited to the description of the embodiment, and that various modifications and improvements are possible.

For example, in the embodiment described above, the circumferential belt 65 was provided, but the circumferential belt 65 is not essential. That is, depending on the application of the pneumatic tire 10, the reinforcing belt 70 is provided outside the crossing belts (the inclined belts 61 and 63) in the tire radial direction, and the tread 41 (tread rubber) is provided outside the reinforcing belt 70 in the tire radial direction. The structure provided may be sufficient.

Further, other than the circumferential belt 65, another reinforcing belt, for example, a belt (which may be called a cap layer or the like) that covers the tire width direction end of the intersecting belt may be provided.

In the present embodiment, the reinforcing belt 70 is provided to the vicinity of the ground contact edges on the outer side (OUT side) when mounted on the vehicle and the inner side (IN side) when mounted on the vehicle, but the width of the reinforcing belt 70 is based on the tire equatorial plane CL. If provided on the OUT side and the IN side as described above, they may be narrowed to some extent.

Also, FIG. 4 describes a pneumatic tire 10A according to Modification 1 of the embodiment. FIG. 4 is a cross-sectional view of a pneumatic tire 10A according to Modification 1 along the tire radial direction and the tire width direction.

The pneumatic tire 10A according to Modification 1 differs from the pneumatic tire 10 of the present embodiment in that an additional cushioning rubber layer 80 is arranged between the reinforcing belt 70 and the belt layer 60. Other configurations of the pneumatic tire 10</b>A are the same as those of the pneumatic tire 10 .

The Young's modulus of the buffer rubber layer 80 is equal to or less than the elastic modulus of the coating rubber 65b of the circumferential belt 65 located at the tire radial direction outer end of the belt layer 60, or equal to or less than the elastic modulus of the coating rubber 70b of the reinforcing belt 70. .

As for the thickness of the cushioning rubber layer 80, the width in the tire radial direction is 0.2 mm or more and 1.5 mm or less. Moreover, the width of the buffer rubber layer 80 overlaps with the reinforcing belt 70 over the entire width.

In the pneumatic tire 10A according to Modification 1, even if a large load is applied to the tire attached to the wheel during high-speed turning, and the belt layer 60 is deformed in the tire width direction due to the deformation of the tire due to this load, the cushioning is performed. The shear stress generated between the belt layer 60 and the reinforcing belt 70 is effectively relieved by the rubber layer 80 .

5 and 6 describe a pneumatic tire 10B according to Modification 2. FIG. FIG. 5 is a cross-sectional view of a pneumatic tire 10B according to Modification 2 along the tire radial direction and the tire width direction. FIG. 6 is a partial plan development view of the tread of a pneumatic tire 10B according to Modification 2. As shown in FIG.

In the pneumatic tire 10 of the present embodiment, the pattern of the tread 41 is not particularly limited and illustration thereof is omitted. A pneumatic tire 10B according to Modification 2 has a cross-sectional structure similar to that of the pneumatic tire 10 according to the embodiment, as shown in FIG. On the outer surface of the pneumatic tire 10B, as shown in FIG. 6, a tread having an asymmetrical pattern with a low negative rate, which is the volume of grooves formed on the outer side (OUT side) when mounted on the vehicle, with respect to the tire equatorial plane CL. 41B pattern (tread pattern) can be formed.

Here, the volume of the groove that defines the negative rate may be interpreted as the area (or volume) of the portion that does not contact the road surface under the above-described normal internal pressure and normal load. On the other hand, the portion that touches the road surface under normal internal pressure and normal load may be interpreted as a land portion.

In addition, such a groove-to-land ratio may be defined as a so-called negative rate. The negative ratio can be expressed simply as groove/(land+groove), but more precisely, the entire tread 41B obtained by projecting the entire circumference (or unit length (pitch)) of the tread 41B two-dimensionally. It may be interpreted as the ratio of grooves to area.

Further, as described above, the contact edge in the tire width direction required to determine the area of the land portion is the maximum load capacity (load index) corresponding to the maximum load capacity (load index) of the pneumatic tire 10B set to the normal internal pressure. The maximum load) may be applied as a reference.

Specifically, as shown in FIG. 5, a pneumatic tire 10B according to Modification Example 2 has a pneumatic tire 10B according to the embodiment except that a pattern such as a circumferential groove 43B is formed in a tread 41B of a tread portion 40B. It may have a cross-sectional structure similar to that of the entered tire 10 .

In the tread pattern of the pneumatic tire 10B according to Modification 2, as shown in FIG. 6, a plurality of circumferential grooves 43B, widthwise sipes 45B, shoulder grooves 47B and lug grooves 49B may be formed in the tread 41B.

Specifically, the circumferential groove 43B is a linear main groove extending along the tire circumferential direction. With the tire equatorial plane CL as a reference, two circumferential grooves 43B are formed on the IN side, and one circumferential groove 43B is formed on the OUT side. Thus, the groove formed on the outside (OUT side) when mounted on the vehicle may include at least one circumferential groove 43B.

The width direction sipes 45B are linear sipes extending in the tire width direction, and are formed in plurality at regular intervals in the tire circumferential direction.

The sipe is a narrow groove that closes in the contact surface of the tread 41B, and the opening width of the sipe when not contacting the ground is not particularly limited, but is preferably 0.1 mm to 1.5 mm.

The shoulder groove 47B is formed in the tread shoulder portion on the IN side. In Modification 2, the shoulder groove 47B extends in the tire width direction and has a shape that is bent at the central portion.

The lug groove 49B is formed in the tread shoulder portion on the OUT side. The lug grooves 49B are inclined with respect to the tire width direction along the tire width direction. That is, the lug grooves 49B are not parallel to the tire width direction, but are inclined with respect to the tire width direction.

The inclination angle of the lug grooves 49B with respect to the tire width direction is 45 degrees or less, similar to the width direction sipes 45B, and is 30 degrees or less in consideration of both the rigidity of the outer shoulder land portion and suppression of pass-through noise (PBN). is preferred.

Also, the peripheral portion of the lug groove 49B may be inclined inward in the tire radial direction from the tread surface side of the tread 41B (outer shoulder land portion). Such an inclination may be called a chamfer (chamfer) or the like.

In this way, in the pneumatic tire 10B according to Modification 2, the grooves (specifically, one circumferential groove 43B and the lugs 43B) formed in the tread 41B on the outside when mounted on the vehicle with respect to the tire equatorial plane CL The volume of the groove 49B) is the groove portion (specifically, the two circumferential grooves 43B, the widthwise sipes 45B, and the shoulder grooves 47B) formed in the inner tread 41B when mounted on the vehicle with reference to the tire equatorial plane CL. is less than the volume of

In order to facilitate the calculation of the negative ratio, only the main groove portion of the tread 41B may be treated as the groove portion, and the other grooves may be excluded. Specifically, in the present embodiment, the circumferential groove 43B extending in the tire circumferential direction is the target of the groove portion, and the widthwise sipe 45B, the shoulder groove 47B and the lug groove 49B extending in the tire width direction are calculated for the negative rate. may be excluded from

The entire contents of Japanese Patent Application No. 2021-102351 (filing date: June 21, 2021) are incorporated herein.

Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described in the present disclosure. The present disclosure can be practiced with modifications and variations without departing from the spirit and scope of the present disclosure as defined by the claims. Accordingly, the description of the present disclosure is for illustrative purposes and is not meant to be limiting in any way.

Claims

a tread in contact with the road surface;
A belt layer having a plurality of belts provided inside the tread in the tire radial direction;
An annular carcass layer that is provided inside the belt layer in the tire radial direction and forms a frame of the tire,
Between the belt layer and the tread, a reinforcing belt extending along the tire width direction and the tire radial direction and covered with a plurality of reinforcing cords arranged at a predetermined distance,
In the tire cross section along the tire radial direction and the tire width direction,
An outer end portion of at least one belt included in the belt layer in the tire width direction, which is the outer side when mounted on a vehicle, is located radially inward of an inner end portion which is the inner side when mounted on the vehicle, and the tire width A pneumatic tire, wherein, in a direction, the width from the tire equatorial plane to the outer edge is greater than the width from the tire equatorial plane to the inner edge.
In the tire cross section,
A first end portion of the reinforcement belt in the tire width direction, which is positioned outside when the belt is mounted on the vehicle, is located radially inward of a second end portion, which is the inside when the belt is mounted on the vehicle, in the tire width direction, and the tire equator is positioned in the tire width direction. The pneumatic tire according to claim 1, wherein the width from the plane to the first end is wider than the width from the tire equatorial plane to the second end.
In the tire cross section,
The outer end of each belt of the belt layer in the tire width direction is located radially inward of the inner end of the belt, and the tire equatorial plane of each belt of the belt layer in the tire width direction 3 . The pneumatic tire according to claim 1 , wherein a width from to the outer end is wider than a width from the tire equatorial plane to the inner end.
The pneumatic tire according to any one of claims 1 to 3, further comprising a buffer rubber layer arranged between said belt layer and said reinforcing belt.