WO2019244776A1

WO2019244776A1 - Pneumatic tyre

Info

Publication number: WO2019244776A1
Application number: PCT/JP2019/023525
Authority: WO
Inventors: 好秀河野; 正之有馬
Original assignee: 株式会社ブリヂストン
Priority date: 2018-06-21
Filing date: 2019-06-13
Publication date: 2019-12-26
Also published as: JP2019217957A

Abstract

This pneumatic tire is provided with a tire case which is configured to include a carcass extending from one bead portion to another bead portion, and in which at least an outside portion, in the width direction of the tire, of the carcass is covered by a rubber material, and a belt which is configured by coating reinforcing cords, wound in the circumferential direction of the tire, with resin, and which is joined to an outer circumferential side of the carcass, wherein, in a cross section through the belt in the width direction of the tire, the number of reinforcing cords per unit width of the belt is greater in end portions in the width direction of the tire than in a central portion in the width direction of the tire.

Description

Pneumatic tire

The present disclosure relates to a pneumatic tire provided with a belt including a cord wound in a spiral shape.

As a pneumatic tire to be mounted on an automobile, for example, as disclosed in JP-A-2013-244930 and JP-A-2013-220743, the tire is inclined outward in the tire radial direction of the carcass with respect to the tire circumferential direction. Generally, a structure including a belt composed of two or more inclined belt plies including a cord and a plurality of layers including a reinforcing layer and the like disposed outside the inclined belt plies in the tire radial direction is generally used.

On the other hand, Japanese Patent Application Laid-Open No. 2018-0665426 discloses a tire having a belt formed by spirally winding a resin-coated cord formed by coating a reinforcing cord with a resin in the tire circumferential direction on the outer periphery of a tire frame member. Is disclosed.

The pneumatic tires disclosed in JP-A-2013-244930 and JP-A-2013-220743 are provided with two or more inclined belt plies and a reinforcing layer, and thus are necessary for reinforcing the carcass crown. Although it is possible to secure in-plane shear rigidity and the like, it is difficult to reduce the weight of the tire due to the large number of plies and reinforcing layers.

Therefore, it is possible to reduce the weight by forming a pneumatic tire provided with a resin belt disclosed in Japanese Patent Application Laid-Open No. 2018-065426 instead of the belt including the inclined belt ply and the reinforcing layer. However, in this case, the tension in the circumferential direction of the tire acting on the belt cannot be supported by a plurality of skewed cords as in the conventional inclined belt ply, and the reinforcing cords extending in the circumferential direction of the tire independently support each other. It becomes. On the other hand, the tension in the tire circumferential direction acting on the belt increases toward the end in the tire width direction, so that the tension borne by one reinforcing cord increases toward the end in the tire width direction. Therefore, when the conventional belt is simply replaced with a resin belt in the pneumatic tire, it is difficult to improve the durability.

The present disclosure aims to provide a pneumatic tire that can ensure the durability of a belt when a belt is formed by covering a reinforcing cord with a resin.

The pneumatic tire of the present disclosure is configured to include a carcass straddling from one bead portion to the other bead portion, at least a tire case in which an outer portion in the tire width direction of the carcass is covered with a rubber material, and a tire circumferential direction. And a belt joined to the outer peripheral side of the tire case, wherein the reinforcing cord is wound around the belt, and is joined to an outer peripheral side of the tire case. Are greater at the end in the tire width direction than at the center in the tire width direction.

ベルト The pneumatic tire belt according to the present disclosure includes a reinforcing cord covered with a resin. The number of reinforcing cords per unit width in the cross section in the tire width direction of the belt is larger at the end portion in the tire width direction where the tension in the tire circumferential direction acting on the belt is larger, so that the tension borne by one reinforcing cord is equalized. can do. Thereby, the durability of the belt including the reinforcing cord can be secured.

According to the pneumatic tire of the present disclosure, when forming a belt by covering a reinforcing cord with a resin, the durability of the belt can be ensured.

1 is a cross-sectional view along a tire rotation axis showing a pneumatic tire according to a first embodiment. It is an expanded sectional view showing the neighborhood of the shoulder of the pneumatic tire concerning a 1st embodiment. It is a sectional view of a belt of a pneumatic tire concerning a 1st embodiment. It is a sectional perspective view showing a process of winding a resin coating cord on a belt forming drum. FIG. 7 is a cross-sectional view (a cross-sectional view taken along line 5-5 in FIG. 6) of the belt of the pneumatic tire according to the second embodiment. It is a top view of a belt of a pneumatic tire concerning a 2nd embodiment.

[First Embodiment]
A pneumatic tire 10 according to an embodiment of the present disclosure will be described with reference to FIGS.

As shown in FIG. 1, the pneumatic tire 10 of the present embodiment is, for example, a so-called radial tire used for a passenger car, includes a pair of bead portions 20 in which a bead core 12 is embedded, and one bead portion 20 and the other bead portion. A carcass 16 composed of one carcass ply 14 straddles the bead portion 20. FIG. 1 shows the shape of the pneumatic tire 10 in a natural state before air filling. The carcass 16 is an example of a tire case.

The carcass ply 14 is formed by coating a plurality of cords (not shown) extending in the radial direction of the pneumatic tire 10 with a coating rubber (not shown). That is, the pneumatic tire 10 of the present embodiment is a so-called radial tire. The cord material of the carcass ply 14 is, for example, PET, but may be another known material.

The end portion of the carcass ply 14 in the tire width direction (tire axial direction) has the bead core 12 folded back in the tire radial direction. In the carcass ply 14, a portion extending from one bead core 12 to the other bead core 12 is referred to as a main body portion 14A, and a portion folded from the bead core 12 is referred to as a folded portion 14B.

Bead fillers 18 whose thickness gradually decreases from the bead core 12 to the outside in the tire radial direction are disposed between the main body portion 14A and the folded portion 14B of the carcass ply 14. In the pneumatic tire 10, a portion of the bead filler 18 from the tire radial outer end 18 </ b> A to the tire radial direction inside is a bead portion 20.

An inner liner 22 made of rubber is arranged inside the tire of the carcass 16, and a side rubber layer 24 made of the first rubber material is arranged outside the carcass 16 in the tire width direction.

In the present embodiment, the tire case 25 is constituted by the bead core 12, the carcass 16, the bead filler 18, the inner liner 22, and the side rubber layer 24. The tire case 25 is, in other words, a tire frame member that forms the frame of the pneumatic tire 10.

(belt)
A belt 26 is arranged outside the crown portion of the carcass 16, in other words, outside the carcass 16 in the tire radial direction, and the belt 26 is in close contact with the outer peripheral surface of the carcass 16. As shown in FIG. 2, the belt 26 is formed by winding a resin-coated cord 34 in which a plurality of reinforcing cords 30 are covered with a resin 32 in the tire circumferential direction. The method of manufacturing the belt 26 will be described later.

Here, in the resin-coated cord 34 of the present embodiment, the number of the reinforcing cords 30 that are covered with the resin 32 is set such that the belt 26 is larger at the end in the tire width direction than at the center in the tire width direction. I have. The end of the belt 26 in the tire width direction refers to a predetermined range from the end of the belt 26 in the tire width direction, and is preferably a region of 15 to 30% of the width BW of the belt 26. The central portion of the belt 26 in the tire width direction refers to a predetermined range around the tire equatorial plane CL, and is preferably 40 to 70% of the width BW of the belt 26 sandwiched between the end portions in the tire width direction. Area. The width BW of the belt 26 refers to a range from one tire width direction end of the belt 26 to the other tire width direction end.

In the present embodiment, as shown in FIG. 3, in the cross section in the tire width direction, the resin-coated cords 34 at the end portions of the belt 26 in the tire width direction (five on both sides in the tire width direction) each have three reinforcements. The cords 30 are covered with the resin 32, and the resin-coated cords 34 at the center portion of the belt 26 in the tire width direction (the sixth and subsequent cords from both ends in the tire width direction) are each formed of two reinforcing cords 30 with the resin 32. Here, in the belt 26, the range in which the number of the reinforcing cords 30 to be covered is larger than the central portion in the tire width direction is a range of 1/4 of the width BW of the belt 26 from the end in the tire width direction of the belt 26. In particular, it is desirable that the groove 37 be described below and be in a range outside the groove 37 at the end in the tire width direction.

It is preferable that the reinforcing cord 30 of the belt 26 is thicker than the cord of the carcass ply 14 and has high strength (tensile strength). The reinforcing cord 30 of the belt 26 can be composed of a monofilament (single wire) such as a metal fiber or an organic fiber, or a multifilament (stranded wire) obtained by twisting these fibers. The reinforcing cord 30 of the present embodiment is a steel cord. As the reinforcing cord 30, for example, a “1 × 5” steel cord having a diameter of 0.225 mm can be used, but a steel cord having another conventionally known structure can also be used.

(4) As the resin 32 for covering the reinforcing cord 30, a rubber material forming the side rubber layer 24 and a resin material having a higher tensile modulus than a second rubber material forming a tread 36 described later are used. As the resin 32 that covers the reinforcing cord 30, a thermoplastic resin having elasticity, a thermoplastic elastomer (TPE), a thermosetting resin, or the like can be used. Considering the elasticity during running and the moldability during manufacturing, it is desirable to use a thermoplastic elastomer.

Examples of the thermoplastic elastomer include polyolefin-based thermoplastic elastomer (TPO), polystyrene-based thermoplastic elastomer (TPS), polyamide-based thermoplastic elastomer (TPA), polyurethane-based thermoplastic elastomer (TPU), and polyester-based thermoplastic elastomer (TPC). And dynamically crosslinked thermoplastic elastomers (TPV).

Further, examples of the thermoplastic resin include a polyurethane resin, a polyolefin resin, a vinyl chloride resin, and a polyamide resin. Further, as the thermoplastic resin material, for example, the deflection temperature under load (under a load of 0.45 MPa) specified in ISO75-2 or ASTM D648 is 78 ° C. or more, and the tensile yield strength specified in JIS K7113 is 10 MPa. As described above, a material having a tensile elongation at break specified in JIS K 7113 of 50% or more and a Vicat softening temperature (A method) specified in JIS K 7206 of 130 ° C. or more can be used.

引張 The tensile modulus of elasticity of the resin 32 that covers the reinforcing cord 30 (defined by JIS K7113: 1995) is preferably 100 MPa or more. The upper limit of the tensile modulus of the resin 32 covering the reinforcing cord 30 is preferably 1000 MPa or less. The tensile modulus of the resin 32 covering the reinforcing cord 30 is particularly preferably in the range of 200 to 700 MPa.

It is preferable that the thickness t of the belt 26 of the present embodiment is larger than the diameter of the reinforcing cord 30. In other words, it is preferable that the reinforcing cord 30 is completely embedded in the resin 32. When the pneumatic tire 10 is for a passenger car, the thickness t of the belt 26 is preferably set to 0.70 mm or more.

As shown in FIG. 1, a tread 36 made of a second rubber material is disposed outside the belt 26 in the tire radial direction. As the second rubber material used for the tread 36, a generally known material is used. A groove 37 for drainage is formed in the tread 36. Further, the tread 36 has a conventionally known pattern.

幅 It is preferable that the width BW of the belt 26 measured along the tire width direction is 75% or more with respect to the contact width TW of the tread 36 measured along the tire width direction. In addition, it is preferable that the upper limit of the width BW of the belt 26 be 110% with respect to the contact width TW.

Here, the contact width TW of the tread 36 means that the pneumatic tire 10 is mounted on a standard rim stipulated in JATMA YEAR BOOK (2018 edition, Japan Automobile Tire Association Standard) and the applicable size in JATMA YEAR BOOK. Fills with 100% internal pressure of the air pressure (maximum air pressure) corresponding to the maximum load capacity (the bold load in the internal pressure-load capacity correspondence table) in the ply rating, and the rotation axis is parallel to the horizontal flat plate in a stationary state And a mass corresponding to the maximum load capacity is added. When the TRA standard and the ETRTO standard are applied at the place of use or the place of manufacture, the respective standards are followed.

ベルト In addition, the in-plane shear rigidity of the belt 26 is preferably equal to or greater than that of the belt formed by rubber coating.

(Method of manufacturing pneumatic tires)
Next, an example of a method for manufacturing the pneumatic tire 10 of the present embodiment will be described.

First, an inner liner 22 made of a rubber material, a bead core 12, a bead filler 18 made of a rubber material, a carcass ply 14 having a cord covered with a rubber material, and a side rubber layer 24 are provided on the outer periphery of a known tire forming drum (not shown). An unvulcanized tire case 25 is formed. The manufacturing method up to here is the same as the conventional one.

On the other hand, the resin-coated cord 34 (shown by a two-dot chain line in FIGS. 2 and 3) is formed by covering two or three reinforcing cords 30 with the resin 32 for covering. For example, when forming the resin-coated cord 34, first, the three reinforcing cords 30 are covered with the resin 32 to a length wound by １／ of the width BW of the belt 26. Then, the reinforcing cord 30 at the center in the width direction among the three is cut, and the two reinforcing cords 30 are covered with the resin 32 until the reinforcing cord 30 reaches a length wound by 分 of the width BW of the belt 26. After one reinforcing cord 30 is inserted again between the two reinforcing cords 30, the three reinforcing cords 30 reach a length wound by １／ of the width BW of the belt 26. Up to the resin 32.

In the present embodiment formed as described above, the cross-sectional shape of the resin-coated cord 34 is a rectangle (a rectangle that is long in the tire width direction).
The belt 26 is formed by spirally winding a resin-coated cord 34.

Hereinafter, an example of a manufacturing process of the belt 26 will be described with reference to FIG.
First, the cord supply device 42, the heating device 50, the pressing roller 60, and the cooling roller 70 are movably disposed near the belt forming drum 40.

The cord supply device 42 guides the reel 43 around which the resin-coated cord 34 in which the reinforcing cord 30 is coated with the coating resin 32 and the resin-coated cord 34 unwound from the reel 43 to the outer periphery of the belt forming drum 40. And a guide member 44 for performing the operation. The guide member 44 has a cylindrical shape, and the resin-coated cord 34 passes through the inside thereof. Further, the resin-coated cord 34 is sent out from the mouth 46 of the guide member 44 toward the outer peripheral surface of the belt forming drum 40.

The heating device 50 blows hot air onto the resin-coated cord 34 to heat and melt the blown portion. In the present embodiment, air heated by a heating wire (not shown) is blown out from the outlet 52 by an airflow generated by a fan (not shown), and the blown hot air is blown against the resin-coated cord 34. ing. The configuration of the heating device 50 is not limited to the above configuration, and may be any configuration as long as the thermoplastic resin can be heated and melted. For example, a hot iron may be brought into contact with the side surface of the resin-coated cord 34 to heat and melt the side surface, may be heated and melted by radiant heat, or may be heated and melted by irradiating infrared rays.

The pressing roller 60 is for pressing a resin-coated cord 34 described later against the outer peripheral surface of the belt forming drum 40, and is capable of adjusting the pressing force F. Further, the roller surface of the pressing roller 60 is processed to prevent the resin material in a molten state from adhering. The pressing roller 60 is rotatable. When the resin-coated cord 34 is pressed against the outer periphery of the belt forming drum 40, the pressing roller 60 is driven to rotate in the rotation direction (the direction of the arrow A) of the belt forming drum 40. It has become.

The cooling roller 70 is disposed downstream of the pressing roller 60 in the rotation direction of the belt forming drum 40, and cools the resin coating cord 34 while pressing the resin coating cord 34 against the outer peripheral surface of the belt forming drum 40. is there. Like the pressing roller 60, the cooling roller 70 is capable of adjusting the pressing force, and has been subjected to processing for preventing adhesion of a molten resin material to the roller surface. Further, the cooling roller 70 is rotatable similarly to the pressing roller 60, and when the resin-coated cord 34 is pressed against the outer peripheral surface of the belt forming drum 40, the rotation direction of the belt forming drum 40 (arrow A) Direction). The cooling roller 70 is configured such that a liquid (for example, water) flows through the inside of the roller, and a member (the resin-coated cord 34 in the present embodiment) that comes into contact with the roller surface by heat exchange of the liquid. Can be cooled. When the resin material in the molten state is naturally cooled, the cooling roller 70 may be omitted.

Next, the belt forming drum 40 is rotated in the direction of arrow A, and the resin-coated cord 34 is sent out from the mouth 46 of the cord supply device 42 toward the outer peripheral surface of the belt forming drum 40.

Then, while the hot air is blown out from the outlet 52 of the heating device 50 toward the resin-coated cord 34 and heated to melt the surface of the resin 32, the resin-coated cord 34 is attached to the belt forming drum 40 while Is pressed against the outer peripheral surface of the belt forming drum 40 by the pressing roller 60. The resin-coated cord 34 is deformed (deformed by crushing) so that the side portion swells in the tire width direction by the pressing roller 60, and the side surfaces of the resin 32 adjacent to each other in the tire width direction come into contact with each other and weld. .
Thereafter, the molten portion of the resin 32 contacts the cooling roller 70 and is solidified, and the welding of the adjacent resin-coated cords 34 is completed.

In this manner, the resin-coated cord 34 is spirally wound around the outer peripheral surface of the belt forming drum 40 and pressed against the outer peripheral surface, whereby the belt 26 is formed on the outer peripheral surface of the belt forming drum 40. In order to spirally wind the resin-coated cord 34, the position of the mouth 46 of the cord supply device 42 is moved in the tire width direction with the rotation of the tire case 17, or the tire case 17 is moved in the tire width direction. You can move it.

Next, the belt 26 in which the resin 32 has been solidified is removed from the belt forming drum 40, and disposed outside the tire case of the tire forming drum in the radial direction, and the tire case is expanded to expand the outer peripheral surface of the tire case, in other words, the outer periphery of the carcass 16. The surface is pressed against the inner peripheral surface of the belt 26.

Finally, an unvulcanized tread 36 is attached to the outer peripheral surface of the belt 26 in the same manner as a general pneumatic tire, and a green tire is completed.

The green tire thus manufactured is vulcanized and molded by a vulcanization mold in the same manner as a general pneumatic tire, and the pneumatic tire 10 is completed.

(Action, effect)
Next, the operation and effect of the pneumatic tire 10 of the present embodiment will be described.

In the pneumatic tire 10 of the present embodiment, the crown portion of the carcass 16 is reinforced by the belt 26 covered with the resin 32 on the reinforcing cord 30 wound in a spiral shape. Compared to a belt composed of a plurality of layers composed of a belt ply, it is lighter in weight and easier to manufacture.

In the belt 26 of the present embodiment, the tensile modulus of the resin 32 covering the reinforcing cord 30 is set to 50 MPa or more and the thickness is secured to 0.7 mm or more, so that the in-plane shearing of the belt 26 in the tire width direction is performed. The rigidity can be sufficiently secured.

By ensuring the in-plane shear stiffness of the belt 26, lateral force can be sufficiently generated when the pneumatic tire 10 is given a slip angle, steering stability can be ensured, and the response can be improved. Performance can also be improved.

In addition, by securing the out-of-plane bending rigidity of the belt 26, when a large lateral force is input to the pneumatic tire 10, the buckling of the tread 36 (the surface of the tread 36 undulates and a part of the tread 36 is separated from the road surface) Phenomenon).

Further, in the pneumatic tire 10 of the present embodiment, the belt 26 having a high in-plane shear rigidity is used, and the width BW of the belt 26 is set to be 75% or more of the contact width TW of the tread 36, so that the rigidity near the shoulder 39 is obtained. Can be increased.

In the pneumatic tire 10 of the present embodiment, since the belt 26 has a one-layer structure, the thickness of the belt 26 can be reduced as compared with a conventional case where two or more belt plies are used, and the tread 36 The thickness can be increased, and the depth of the groove 37 can be increased. As a result, the life of the pneumatic tire 10 can be extended.

In the belt 26 of the pneumatic tire 10, the reinforcing cord 30 is spirally wound, and there is no portion where the reinforcing cord 30 overlaps in the tire radial direction on the circumference, and the thickness is uniform in the tire circumferential direction. The pneumatic tire 10 is excellent in uniformity.

By the way, in the pneumatic tire, the belt is formed so as to have a slightly smaller diameter at the end side in the tire width direction than at the center side in the tire width direction according to the shape of the tire case. Therefore, when the pneumatic tire rolls, the belt receives the force in the tire expanding direction at the end in the tire width direction, that is, the tension in the tire circumferential direction, and the tire contracts at the center in the tire width direction. Directional force, that is, a compressive force in the tire circumferential direction.

Here, when a resin-coated cord in which a reinforcing cord is coated with a resin is formed, and the resin-coated cord is spirally wound to form a belt, the tension in the tire circumferential direction acting on the belt is the same as in a conventional inclined belt ply. Cannot be supported by multiple codes skewed. Therefore, in the resin belt, the tension in the tire circumferential direction has a structure in which the reinforcing cords extending in the tire circumferential direction are independently supported. On the other hand, the tension in the tire circumferential direction acting on the belt increases toward the end in the tire width direction, so that the tension borne by one reinforcing cord increases toward the end in the tire width direction. Therefore, in the case where the conventional belt is simply replaced with a resin belt in the pneumatic tire, the load on the reinforcing cord at the end portion in the tire width direction becomes large, so that it is difficult to improve the durability.

On the other hand, according to the belt 26 of the present embodiment, the number of the reinforcing cords 30 covered with the resin 32 in the resin-coated cords 34 is greater at the end in the tire width direction than at the center in the tire width direction. It is set as follows. That is, in the belt 26 of the present embodiment, the number of the reinforcing cords 30 per unit width in the tire width direction cross section is larger at the tire width direction end side where the tension is larger, so that the tension borne by one reinforcing cord 30 is smaller. Can be equalized. Thereby, the durability of the belt 26 including the reinforcing cord 30 can be ensured.

The belt 26 of the present embodiment is configured by winding a resin-coated cord 34 in which a plurality of reinforcing cords 30 are covered with a resin 32, and changes the number of the reinforcing cords 30 arranged on the resin-coated cord 34. By doing so, the number of reinforcing cords 30 per unit width is changed. Therefore, the number of reinforcing cords 30 at the end portion in the tire width direction can be increased without changing the winding method of the resin-coated cord 34, and the durability of the belt 26 can be improved without increasing the number of man-hours for manufacturing the belt 26. Can be secured.

ベルト In the belt 26 of the present embodiment, the number of the reinforcing cords 30 is increased in a range of 1/4 of the width BW of the belt 26 from the end in the tire width direction. This range is a range outside the groove 37 at the end in the tire width direction among the grooves 37. According to the present embodiment, by increasing the number of the reinforcing cords 30 outside the groove 37, the tension load near the shoulder 39 can be reduced.

[Second embodiment]
Next, a pneumatic tire 10 according to a second embodiment of the present disclosure will be described. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 5, the belt 26 of the present embodiment is formed by winding a resin-coated cord 34 in which one reinforcing cord 30 is covered with a resin 32 in the tire circumferential direction. In the present embodiment, the number of reinforcing cords 30 per unit width is changed by changing the feed speed in the tire width direction when winding the resin-coated cords 34, in other words, by changing the interval between adjacent resin-coated cords 34. Let me.

樹脂 As shown in FIG. 6, in the resin-coated cords 34 from the end in the tire width direction to the ninth winding, the side surfaces of the resins 32 that are adjacent to each other in the tire width direction are directly joined by welding. Further, in the resin-coated cord 34 of the tenth and subsequent turns, the feeding speed in the tire width direction at the time of winding is increased. Therefore, a gap is formed between adjacent resin-coated cords 34, and in the present embodiment, the filling portion 33 is formed by filling the gap with a resin. That is, the adjacent resin-coated cords 34 are joined at the filling portion 33 via the resin.

It is desirable that the resin forming the filling portion 33 be the same material as the resin 32 forming the resin-coated cord 34.

In the present embodiment, the range in which the interval between the adjacent resin-coated cords 34 is narrower than the central portion in the tire width direction is preferably set to a range of １／ of the width BW of the belt 26 from the end in the tire width direction. In particular, it is desirable to be a range outside the groove 37 at the end in the tire width direction among grooves 37 described later.

において In this embodiment, the same operation and effect as those of the first embodiment can be obtained. Further, according to the present embodiment, since it is not necessary to form the resin-coated cords 34 in which the number of the reinforcing cords 30 is changed in the length direction, the belt 26 can be formed without increasing the man-hour for manufacturing the resin-coated cords 34. Durability can be ensured.

[Other embodiments]
Although the embodiments of the present disclosure have been described above, the present invention is not limited to the above, and it goes without saying that the present invention can be variously modified and implemented without departing from the gist thereof. is there. Further, the features of each embodiment may be combined.

In the first embodiment, the belt 26 is formed by winding the resin-coated cord 34. However, the present invention is not limited to this, and the belt 26 may be formed of a single cylindrical body made of resin. For example, the reinforcing cord 30 is wound around the outer periphery of a resin ring formed in a cylindrical shape in advance so that the number of end portions in the tire width direction is larger than that in the central portion in the tire width direction. Is further covered with a resin 32. Here, the resin-made cylindrical ring can be formed by cutting a resin cylinder formed by injection molding or extrusion molding into a predetermined length.

ベルト The belt 26 composed of one cylindrical body as described above also has the same function and effect as the first embodiment. In the case of a belt formed by winding a resin-coated cord and joining adjacent portions together, the belt may be divided in the width direction due to poor welding, but the belt 26 has an interface in the tire width direction. Therefore, there is no fear that the belt 26 is separated in the tire width direction due to poor welding, and the durability can be improved. Further, as compared with the case where the belt is formed by welding the resin-coated cord, the number of steps is reduced, so that the productivity is improved and the cost can be reduced.

Also, in the first embodiment, the resin-coated cord 34 used when manufacturing the belt 26 is formed by covering two or three reinforcing cords 30 with the resin 32, but the present invention is not limited to this. That is, if the number of reinforcing cords 30 per unit width in the cross section of the belt 26 in the tire width direction is larger at the end in the tire width direction than at the center in the tire width direction, three or more reinforcing cords 30 are covered. There may be.

The cross section of the resin-coated cord 34 of the above embodiment is rectangular, and as shown in FIG. 2, an inner peripheral surface 34A on the carcass 16 side (lower side in the drawing) and an outer peripheral surface 34B on the tread 36 side (upper side in the drawing). Are not displaced in the belt width direction, but the cross section of the resin-coated cord 34 is not limited to a rectangle, and the inner peripheral surface 34A on the carcass side (the lower side in the drawing) and the outer peripheral surface on the tread side (the upper side in the drawing). 34B may be displaced in the belt width direction. For example, the resin-coated cord 34 may have a parallelogram cross section.

The belt 26 of the present embodiment is not limited to a general pneumatic tire, and may be used for a run flat tire whose side portions are reinforced with reinforcing rubber.

In the belt 26 of the above embodiment, the side surfaces in the tire width direction of the resin-coated cords 34 adjacent in the belt width direction are joined by welding, but may be joined by using an adhesive.

The disclosure of Japanese Patent Application No. 2018-117979 filed on June 21, 2018 is incorporated herein by reference in its entirety.
All documents, patent applications, and technical standards mentioned herein are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference. Incorporated herein by reference.

Claims

A tire case configured to include a carcass straddling from one bead portion to the other bead portion, and at least an outer portion in the tire width direction of the carcass is covered with a rubber material,
A belt that is configured by covering a reinforcing cord wound in the tire circumferential direction with a resin, and that is joined to an outer peripheral side of the tire case,
In a cross section of the belt in the tire width direction, the number of the reinforcing cords per unit width of the belt at the end portion in the tire width direction is larger than that at the center portion in the tire width direction.
The belt is
The resin-coated cord formed by coating the plurality of the reinforcing cords with a resin is spirally wound, and portions of the resin-coated cord adjacent to each other in the tire width direction are joined,
The pneumatic tire according to claim 1, wherein the number of the reinforcing cords in the resin-coated cord is greater at a tire width direction end portion than at a tire width direction center portion.
The belt is
A resin-coated cord formed by coating one reinforcing cord with a resin is spirally wound, and portions of the resin-coated cord adjacent to each other in the tire width direction are joined directly or via a resin. And
The pneumatic tire according to claim 1, wherein an interval between the adjacent resin-coated cords is smaller at a tire width direction end portion than at a tire width direction central portion.
The belt according to any one of claims 1 to 3, wherein the number of the reinforcing cords per unit width of the belt is larger than the central portion in the tire width direction in a range of 1/4 of the width of the belt from the end in the tire width direction. Pneumatic tires.