JP6845086B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire with a belt configured to include a spirally wound cord.

Pneumatic tires to be mounted on automobiles include two or more inclined belt plies configured to include a cord inclined with respect to the tire circumferential direction on the outer side of the carcass in the tire radial direction, and on the outer side of the inclined belt ply in the tire radial direction. A structure including a belt composed of a plurality of layers including an arranged reinforcing layer or the like is common (see, for example, Patent Documents 1 and 2).

JP 2013-244930 Japanese Unexamined Patent Publication No. 2013-220741

Since the pneumatic tires of Patent Documents 1 and 2 are provided with two or more inclined belt plies and a reinforcing layer, it is possible to secure the in-plane shear rigidity required for reinforcing the crown portion of the carcass. However, it is difficult to reduce the weight of the tire due to the large number of plies and reinforcing layers.
In recent years, there has been an increasing need for weight reduction of pneumatic tires, and there is a demand for pneumatic tires that meet these needs.

In consideration of the above facts, an object of the present invention is to provide a pneumatic tire in which the in-plane shear rigidity of the belt is ensured and the weight is reduced.

The pneumatic tire according to claim 1 includes a carcass extending from one bead portion to the other bead portion, and at least the outer portion of the carcass in the tire width direction is coated with a first rubber material. a case, a tread of a second rubber material are arranged in the tire radial direction outer side of the tire casing, the said tire casing is molded separately, the tire is arranged between the tire casing said tread A resin-coated cord that is vulture-bonded to the case and the tread and is formed by coating the cord with a resin having a tensile elasticity higher than that of the first rubber material and the second rubber material in a spiral shape. A single layer that is wound and is integrally bonded to the resin of one of the resin-coated cords and the resin of the other resin-coated cord that are adjacent to each other in the tire width direction in terms of the tire width direction. With a tire.

In the belt of the pneumatic tire according to claim 1, a cord coated with resin is spirally wound, and a resin coating one cord adjacent to the tire width direction and the other cord are coated. The structure is such that the resin is integrally bonded.

Further, in the belt, the first rubber material that covers the outer portion of the carcass and the resin having a higher tensile elastic modulus than the second rubber material that constitutes the tread are continuous in the tire width direction, so that between the cords. Higher in-plane shear rigidity can be obtained as compared with the belt on which the rubber is arranged.

According to the second aspect of the present invention, in the pneumatic tire according to the first aspect, the resin-coated cord has an inner peripheral surface on the carcass side and an outer peripheral surface on the tread side displaced in the belt width direction. There is.

In the resin-coated cord of the pneumatic tire according to claim 2, the inner peripheral surface on the carcass side and the outer peripheral surface on the tread side are displaced in the belt width direction, and the inner peripheral surface on the carcass side and the outer peripheral surface on the tread side are displaced. Compared to a resin-coated cord whose outer peripheral surface is not displaced in the belt width direction, in other words, a resin-coated cord having a rectangular cross-sectional shape, the length of the side surface of the end of the resin-coated cord in the tire width direction can be made longer. You can.

Therefore, when the resin-coated cord is wound in a spiral shape, the side surface of the resin-coated cord on one side in the belt width direction on the tire width direction side and the side surface of the resin-coated cord on the other side on the tire width direction side. The contact area, in other words, the joining area by joining can be increased, and the joining strength between the resin-coated cord on one side in the belt width direction and the resin-coated cord on the other side can be increased.

The invention according to claim 3 is the pneumatic tire according to claim 1 or 2, which is configured to include fibers or cords and is provided with a layer covering the end of the belt.

Since the belt is configured by coating the cord with a resin having a higher tensile elastic modulus than the second rubber material constituting the tread, it has higher rigidity than the second rubber material and is the end portion of the belt in the tire width direction. The stiffness step, which is the difference in stiffness between the rubber material and the second rubber material, becomes large, but in the pneumatic tire according to claim 3, the end portion of the belt is covered with a layer composed of fibers or cords. As a result, the rigidity step between the belt and the second rubber material can be effectively alleviated.

The invention according to claim 4 is the pneumatic tire according to any one of claims 1 to 3, wherein the first rubber material and the said rubber material are formed on the inner peripheral surface of the belt in the tire radial direction. A resin layer made of a resin having a tensile elastic modulus larger than that of the second rubber material is arranged, and the resin layer is integrally bonded to the resin coated with the cord.

In the pneumatic tire according to claim 4, a resin layer made of a first rubber material and a resin having a tensile elastic modulus larger than that of the second rubber material covers the cord on the inner peripheral surface of the belt in the tire radial direction. Since it is integrally formed with the resin, the in-plane shear rigidity of the belt can be further improved.

In the invention according to claim 5, in the pneumatic tire according to any one of claims 1 to 4, the width measured along the tire width direction of the belt is 75 of the ground contact width of the tread. It is set to% or more.

In the pneumatic tire according to claim 5, the width measured along the tire width direction of the belt is set to 75% or more of the ground contact width of the tread, so that the width in which the belt restrains the outer peripheral portion of the carcass is set. Can be taken widely. By restraining the outer periphery of the carcass with a belt, the contact patch of the tread when the pneumatic tire is viewed in a cross section along the tire axis can be flattened, and the width measured along the tire width direction of the belt. Is set to 75% or more of the ground contact width of the tread, so that the ground contact surface of the tread flattened in the tire width direction can be sufficiently secured in the tire width direction. By flattening the tread's tread contact patch when the pneumatic tire is viewed in cross section along the tire axis, the tread's deformation at the time of contact is reduced compared to a pneumatic tire whose tread's tread contact patch is arcuate. It can be suppressed and the rolling resistance of the pneumatic tire can be reduced.

As described above, the pneumatic tire of the present invention has an excellent effect that the in-plane shear rigidity of the belt can be ensured and the weight can be reduced at the same time.

It is sectional drawing along the tire rotation axis which shows the pneumatic tire which concerns on 1st Embodiment of this invention. It is an enlarged cross-sectional view which shows the vicinity of the shoulder of the pneumatic tire which concerns on 1st Embodiment. It is sectional drawing which shows the process of winding a resin coating cord around a belt forming drum. It is an enlarged cross-sectional view which shows the vicinity of the shoulder of the pneumatic tire which concerns on 2nd Embodiment. It is an enlarged cross-sectional view which shows the vicinity of the shoulder of the pneumatic tire which concerns on 3rd Embodiment. It is an enlarged cross-sectional view which shows the vicinity of the shoulder of the pneumatic tire which concerns on the modification of 3rd Embodiment. (A) to (D) are cross-sectional views showing resin coating cords according to other embodiments.

[First Embodiment]
The pneumatic tire 10 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1, the pneumatic tire 10 of the present embodiment is, for example, a so-called radial tire used in 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. A carcass 16 composed of one carcass ply 14 straddles the bead portion 20 of the above. Note that FIG. 1 shows the shape of the pneumatic tire 10 in a natural state before being filled with air.

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 material of the cord of the carcass ply 14 is, for example, PET, but other conventionally known materials may be used.

The carcass ply 14 has a bead core 12 folded outward in the tire radial direction at an end portion in the tire width direction. In the carcass ply 14, the portion extending from one bead core 12 to the other bead core 12 is called a main body portion 14A, and the portion folded back from the bead core 12 is called a folded portion 14B.

A bead filler 18 whose thickness gradually decreases from the bead core 12 toward the outside in the tire radial direction is arranged between the main body portion 14A and the folded-back portion 14B of the carcass ply 14. In the pneumatic tire 10, the bead portion 20 is a portion of the bead filler 18 on the inner side in the tire radial direction from the outer end 18A in the tire radial direction.

An inner liner 22 made of rubber is arranged inside the tire of the carcass 16, and a side rubber layer 24 made of a first rubber material is arranged outside the tire width direction of the carcass 16.
In the present embodiment, the tire case 25 is composed of the bead core 12, the carcass 16, the bead filler 18, the inner liner 22, and the side rubber layer 24. In other words, the tire case 25 is a tire skeleton member that forms the skeleton of the pneumatic tire 10.

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

It is preferable that the reinforcing cord 30 of the belt 26 is thicker than the cord of the carcass ply 14 and has a large 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 (twisted wire) obtained by twisting these fibers. The reinforcing cord 30 of this 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.

As the resin 32 that covers the reinforcing cord 30, a resin material having a higher tensile elastic modulus than the rubber constituting the side rubber layer 24 and the second rubber material constituting the tread 36 described later is used. As the resin 32 for coating the reinforcing cord 30, an elastic thermoplastic resin, 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). , Dynamic crosslinked thermoplastic elastomer (TPV) and the like.

Examples of the thermoplastic resin include polyurethane resin, polyolefin resin, vinyl chloride resin, and polyamide resin. Further, as the thermoplastic resin material, for example, the deflection temperature under load (at 0.45 MPa load) specified in ISO75-2 or ASTM D648 is 78 ° C. or higher, and the tensile yield strength specified in JIS K7113 is 10 MPa. As described above, those having a tensile fracture elongation (JIS K7113) specified in JIS K7113 of 50% or more and a Bikat softening temperature (method A) specified in JIS K7206 of 130 ° C. or more can be used.

The tensile elastic modulus (specified in JIS K7113: 1995) of the resin 32 covering the reinforcing cord 30 is preferably 50 MPa or more. Further, the upper limit of the tensile elastic modulus of the resin 32 covering the reinforcing cord 30 is preferably 1000 MPa or less. The tensile elastic modulus of the resin 32 covering the reinforcing cord 30 is particularly preferably in the range of 200 to 500 MPa.

As shown in FIG. 1, the thickness dimension t of the belt 26 of the present embodiment is preferably larger than the diameter dimension of the reinforcing cord 30, in other words, the reinforcing cord 30 is completely embedded in the resin 32. Is preferable. When the pneumatic tire 10 is for a passenger car, the thickness dimension t of the belt 26 is preferably 0.70 mm or more.

A tread 36 made of a second rubber material is arranged on the outer side of the belt 26 in the tire radial direction. As the second rubber material used for the tread 36, a conventionally known material is used. A drainage groove 37 is formed in the tread 36. Further, as the pattern of the tread 36, a conventionally known pattern is used.

The width BW of the belt 26 measured along the tire axial direction is preferably 75% or more of the ground contact width TW of the tread 36 measured along the tire axial direction. The upper limit of the width BW of the belt 26 is preferably 110% with respect to the ground contact width TW.

Here, the ground contact width TW of the tread 36 means that the pneumatic tire 10 is attached to the standard rim specified in JATMA YEAR BOOK (2016 version, Japan Automobile Tire Association standard), and the applicable size in JATMA YEAR BOOK. The internal pressure is 100% of the air pressure (maximum air pressure) corresponding to the maximum load capacity (internal pressure-load capacity correspondence table in bold) in the ply rating, and the rotation axis becomes parallel to the horizontal flat plate in a stationary state. It is the one when the mass corresponding to the maximum load capacity is added. If the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards will be followed.

Further, the in-plane shear rigidity of the belt 26 is preferably equal to or higher than that of the belt formed of the rubber coating.

(Manufacturing method of pneumatic tires)
Next, an example of the method for manufacturing the pneumatic tire 10 of the present embodiment will be described.
First, from the outer circumference of a known tire forming drum (not shown), an inner liner 22 made of a rubber material, a bead core 12, a bead filler 18 made of a rubber material, a car casply 14 whose cord is coated with a rubber material, and a side rubber layer 24. The unvulcanized tire case 25 is formed. The manufacturing method up to this point is the same as before.

Further, the belt 26 is formed by spirally winding a resin coating cord 34 (shown by a two-dot chain line in FIG. 2) in which two reinforcing cords 30 are coated with a coating resin 32. The cross-sectional shape of the resin coating cord 34 is a rectangle (horizontal width rectangle).

An example of the manufacturing process of the belt 26 will be described below 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 arranged in the vicinity of the belt forming drum 40.

The cord supply device 42 guides the reel 43 around which the resin coating cord 34 obtained by coating the reinforcing cord 30 with the coating resin 32 and the resin coating cord 34 unwound from the reel 43 to the outer periphery of the belt forming drum 40. It is configured to include a guide member 44 for the purpose. The guide member 44 has a tubular shape, and the resin coating cord 34 passes through the inside. Further, the resin coating cord 34 is sent out from the mouth portion 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, the air heated by the heating wire (not shown) is blown out from the outlet 52 by the air flow generated by the fan (not shown), and the blown out hot air is blown to the resin coating 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, the side surface of the resin-coated cord 34 may be brought into contact with a hot iron to heat and melt the side surface, the side surface may be heated and melted by radiant heat, or infrared rays may be irradiated to heat and melt the side surface.

The pressing roller 60 presses the resin-coated cord 34, which will be described later, against the outer peripheral surface of the belt forming drum 40, and the pressing force F can be adjusted. Further, the roller surface of the pressing roller 60 is processed to prevent the resin material in a molten state from adhering to the roller surface. The pressing roller 60 is rotatable, and in a state where the resin coating 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 (arrow A direction) of the belt forming drum 40. It has become like.

Further, the cooling roller 70 is arranged on the downstream side in the rotation direction of the belt forming drum 40 with respect to the pressing roller 60, 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 processed so that the pressing force can be adjusted and the surface of the roller is prevented from adhering to the molten resin material. Further, the cooling roller 70 is rotatable like the pressing roller 60, and in a state where the resin coating 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). It is designed to rotate in a driven manner with respect to the direction). Further, in the cooling roller 70, a liquid (for example, water or the like) circulates inside the roller, and a member (resin coating cord 34 in the present embodiment) or the like that comes into contact with the roller surface by heat exchange of the liquid or the like. Can be cooled. When the molten resin material 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, hot air is blown from the outlet 52 of the heating device 50 toward the resin coating cord 34 to heat the resin 32, and the resin coating cord 34 is attached to the belt forming drum 40 while melting the surface of the resin 32. Is pressed against the outer peripheral surface of the belt forming drum 40 by the pressing roller 60. The pressing roller 60 deforms the resin-coated cord 34 so that the side portions bulge in the tire axial direction (deformation due to crushing), and the side surfaces of the resin 32 adjacent to each other in the tire axial direction are brought into contact with each other and welded. ..
After that, the molten portion of the resin 32 comes into contact with the cooling roller 70 and is solidified, and welding of the adjacent resin coating cords 34 is completed.

In this way, the resin coating cord 34 is spirally wound around the outer peripheral surface of the belt forming drum 40 and pressed against the outer peripheral surface to form the belt 26 on the outer peripheral surface of the belt forming drum 40. In order to wind the resin-coated cord 34 in a spiral shape, the position of the mouth portion 46 of the cord supply device 42 may be moved in the tire axial direction as the tire case 17 rotates, or the tire case 17 may be moved in the tire axial direction. You can move it.

Next, the belt 26 in which the resin 32 is solidified is removed from the belt forming drum, arranged 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 peripheral surface of the carcass 16. Is crimped to the inner peripheral surface of the belt 26.
Finally, the unvulcanized tread 36 is attached to the outer peripheral surface of the belt 26 in the same manner as a general pneumatic tire to complete the raw tire.

The raw tire produced in this manner is vulcanized and molded by a vulcanization molding mold in the same manner as a general pneumatic tire, and the pneumatic tire 10 is completed.

(Action, effect)
Next, the action and effect of the pneumatic tire 10 of the present embodiment will be described.
In the pneumatic tire 10 of the present embodiment, since the crown portion of the carcass 16 is reinforced by the belt 26 in which the spirally wound reinforcing cord 30 is coated with the resin 32, two or more tires of the conventional tire are used. It is lighter and easier to manufacture than a multi-layer belt made of belt ply.

Since the belt 26 of the present embodiment has a tensile elastic modulus of 50 MPa or more and a thickness of 0.7 mm or more of the resin 32 covering the reinforcing cord 30, in-plane shear of the belt 26 in the tire width direction is secured. Sufficient rigidity can be ensured.

By ensuring the in-plane shear rigidity of the belt 26, it is possible to sufficiently generate a lateral force when a slip angle is applied to the pneumatic tire 10, and it is possible to secure steering stability and respond. The sex can also be improved.

Further, by ensuring the out-of-plane bending rigidity of the belt 26, when a large lateral force is applied to the pneumatic tire 10, the buckling of the tread 36 (the surface of the tread 36 is wavy and a part of the tread 36 is separated from the road surface). The phenomenon of tire tread) can be suppressed.

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

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 the case where the belt 26 is composed of two or more conventional belt plies, and the tread 36 can be made thinner by that amount. The thickness can be increased and the depth of the groove 37 can be increased. This also makes it possible to extend the life of the pneumatic tire 10.

The belt 26 in the pneumatic tire 10 has the reinforcing cord 30 spirally wound around the tire, and the reinforcing cord 30 does not overlap in the tire radial direction on the circumference, so that the thickness is uniform in the tire peripheral direction. The pneumatic tire 10 has excellent uniformity.

If the thickness t of the belt 26, in other words, the thickness of the resin 32 is less than 0.7 mm, the reinforcing cord 30 embedded in the resin 32 may be thickened so that the tag effect cannot be obtained.

Further, if the width BW of the belt 26 is less than 75% of the ground contact width TW of the tread 36, the tag effect of the belt 26 becomes insufficient and it becomes difficult to suppress the generation of noise near the shoulder 39. There is a risk. On the other hand, if the width BW of the belt 26 exceeds 100% with respect to the ground contact width TW of the tread 36, the tag effect reaches a plateau, the belt 26 becomes more than necessary, and the weight of the pneumatic tire 10 increases.

[Second Embodiment]
Next, the pneumatic tire 10 according to the second embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.
As shown in FIG. 4, in the pneumatic tire 10 of the present embodiment, the vicinity of the end portion 26A of the belt 26 in the tire width direction is covered with a band-shaped layer 38 from the outside in the tire radial direction. The layer 38 preferably covers at least the outermost reinforcing cord 30 in the tire width direction of the belt 26 from the outer side in the tire radial direction. In the present embodiment, the layer 38 covers up to the second outermost reinforcing cord 30 in the tire width direction. It is covered. Further, the layer 38 covers the end portion 26A of the belt 26 from the outside in the tire width direction, and extends from the end portion 26A of the belt 26 to the outside in the tire width direction along the outer peripheral surface of the carcass 16 to be one of the outer peripheral surfaces of the carcass 16. It covers the part. The layer 38 is joined to the belt 26 and the carcass 16.

As the layer 38, for example, a plurality of cords (not shown) arranged in parallel and coated with rubber can be used. Examples of the cord used for the layer 38 include an organic fiber cord and a steel cord. When a steel cord is used for the layer 38, a cord having a lower bending rigidity than the cord used for the belt 26, in other words, a cord thinner than the cord used for the belt 26 is used. In addition, the layer 38 may use a woven fabric made of fibers or the like or a non-woven fabric instead of the cord. Further, as the layer 38, a cord, a woven fabric, or a non-woven fabric coated with a resin may be used.

Further, the layer 38 may be composed of only a rubber material or a resin material. In this case, the rubber material or resin material forming the layer 38 has an intermediate tensile elastic modulus between the resin 32 covering the reinforcing cord 30 and the rubber material forming the side rubber layer 24 and the second rubber material forming the tread 36. Use the one with.

Looking at the rigidity distribution in the tire width direction, there is a large difference in rigidity between the belt 26 in which the reinforcing cord 30 is embedded and the tread 36 made of only rubber, in other words, the difference in rigidity is large. Stress tends to concentrate in a portion where the rigidity changes significantly, such as near the end portion 26A of the belt 26. In the pneumatic tire 10 of the present embodiment, by covering the end portion 26A of the belt 26 with the layer 38, the rigidity can be gradually changed from the end portion 26A of the belt 26 to the tread 36 when viewed in the tire width direction. , The concentration of stress near the belt end 26A can be suppressed.

In the present embodiment, the layer 38 covers only the vicinity of the end portion 26A of the belt 26, but if necessary, at least one layer 38 formed wide covers the entire belt 26 from the outside in the tire radial direction. You may do so.

[Third Embodiment]
Next, the pneumatic tire 10 according to the third embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.
As shown in FIG. 5, in the pneumatic tire 10 of the present embodiment, a resin layer 33 made of only a resin material is provided between the belt 26 and the carcass 16, and the resin material constituting the resin layer 33 is provided. The belt 26 is joined to the resin 32 by welding to be integrated.

In the production of the belt 26 of the present embodiment, a cylindrical resin layer 33 is arranged on the outer periphery of the belt forming drum, and a resin coating cord 34 obtained by melting the surface of the resin 32 is spirally formed on the outer peripheral surface of the resin layer 33. By winding, the resin layer 33 and the resin 32 of the resin coating cord 34 can be joined and integrated by, for example, welding.

In the pneumatic tire 10 of the present embodiment, the resin layer 33 is integrated with the belt 26 and the resin portion is thickened, so that the in-plane shear rigidity of the belt 26 can be further increased. Further, in the belt 26 of the first embodiment, the resin coating cords 34 adjacent to each other are joined by welding only the side surfaces, but in the belt 26 of the second embodiment, they are adjacent to each other. Since the resin coating cord 34 is welded together not only between the side surfaces but also via the resin layer 33, high bonding strength can be obtained.

As the resin material constituting the resin layer 33, the same resin material as the resin 32 of the belt 26 can be used, but the resin layer 33 may be welded to the resin 32 of the belt 26, and in some cases, the same type of resin as the resin 32. A material having a different hardness may be used, or a resin material of a type different from that of the resin 32 may be used.

As shown in FIG. 6, the width of the resin layer 33 may form a protruding portion 33A that is wider than the width of the belt 26 in which the resin coating cord 34 is spirally wound. With this configuration, a resin-only portion having a rigidity lower than that of the belt 26 is formed at the end of the belt 26 made of the highly rigid resin-coated cord 34, and it becomes easy to alleviate the rigidity step. The end portion 26A of the belt 26 and the protruding portion 33A of the resin layer 33 may be covered with, for example, two layers 38.

Although the resin layer 33 of the present embodiment is injection-molded, it may be used by cutting an extrusion-molded resin cylinder to a predetermined length, and the production method may be used as long as it can be formed as a resin cylinder.

In the present embodiment, since the resin coating cord 34 is spirally wound around the outer peripheral surface of the cylindrical resin layer 33, the resin coating cord 34 is spirally wound around the outer peripheral surface of the belt forming drum, as compared with the case where the resin coating cord 34 is directly wound around the outer peripheral surface of the belt forming drum. Since there is a winding target having a fixed width, it is easy to wind the resin-coated cord 34.

Further, in the present embodiment, the cylindrical belt 26 having excellent uniformity can be easily formed.

By the way, since the resin layer 33 is integrated with the belt 26 of the pneumatic tire 10 of the present embodiment, the out-of-plane bending rigidity is increased as compared with the belt 26 of the pneumatic tire 10 of the first embodiment. This makes it possible to increase the vertical spring constant of the pneumatic tire 10. In other words, the pneumatic tire 10 of the first embodiment having the belt 26 without the resin layer 33 tends to lower the vertical spring constant and improve the riding comfort as compared with the pneumatic tire 10 of the second embodiment.

[Other Embodiments]
Although one embodiment of the present invention has 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 within a range not deviating from the gist thereof. Is.

The belt 26 of the above embodiment was formed with a constant diameter and a constant thickness in the tire axis direction, in other words, it was linear when viewed in a cross section along the tire axis, but the present invention is not limited to this. A circle in which the outer diameter of the central part in the tire width direction is larger than the outer diameter of both ends in the tire width direction, and the central part in the tire width direction is convex outward in the tire radial direction when viewed in a cross section along the tire axis. It may be arcuate.

In the above embodiment, the resin-coated cord 34 used in manufacturing the belt 26 has two reinforcing cords 30 coated with the resin 32, but the resin-coated cord 34 has one reinforcing cord 30. It may be coated with the resin 32, or may be a resin 32 coated with three or more reinforcing cords 30.

The resin-coated cord 34 of the above embodiment has a rectangular cross-sectional shape, and as shown in FIG. 2, the inner peripheral surface 34A on the carcass 16 side (lower side in the drawing) and the outer peripheral surface 34B on the tread 36 side (upper side in the drawing). Although the resin coating cord 34 is not displaced in the belt width direction, the cross-sectional shape of the resin coating cord 34 is not limited to a rectangular shape, and is shown in FIGS. 7 (A), 7 (B), 7 (C), and 7 (D). As described above, the inner peripheral surface 34A on the carcass side (lower side in the drawing) and the outer peripheral surface 34B on the tread side (upper side in the drawing) may be displaced in the belt width direction.

The resin-coated cord 34 shown in FIG. 7 (A) has a parallelogram in cross section, and the side surfaces are inclined at a constant angle. The resin-coated cord 34 shown in FIG. 7 (B) has the side surfaces inclined. At the same time, a step portion is formed in the middle portion, the resin coating cord 34 shown in FIG. 7 (C) has an arc shape on the side surface, and the resin coating cord 34 shown in FIG. 7 (D) has a side surface. Is wavy in an inverted S shape.

Each of the resin-coated cords 34 shown in FIGS. 7A to 7D has a longer side surface length when viewed in cross section than the resin-coated cord 34 having a rectangular cross section shown in FIG. In other words, the bonding area (welding area) between one resin-coated cord 34 and the other resin-coated cord 34 adjacent to each other in the belt width direction is longer than that of the belt 26 shown in FIG. 2, and the bonding strength is increased. Can be enhanced.

The belt 26 of the present embodiment is not limited to a general pneumatic tire, but can also be used for a run-flat tire whose side portion is reinforced with reinforcing rubber.

In the belt 26 of the above embodiment, the side surfaces of the resin coating cord 34 adjacent in the belt width direction in the tire width direction are joined by welding, but they may be joined by using an adhesive. Further, in the third embodiment, the resin layer 33 and the resin 32 of the belt 26 are joined by welding, but they may be joined by using an adhesive.

10 ... Pneumatic tire, 16 ... Carcass, 20 ... Bead part, 24 ... Side rubber layer (first rubber material), 25 ... Tire case, 26 ... Belt, 30 ... Reinforcement cord, 32 ... Resin, 34 ... Resin coating cord , 34A ... inner peripheral surface, 34B ... outer peripheral surface, 36 ... tread (second rubber material), 38 ... layer, 33 ... resin layer, BW ... belt width, TW ... ground contact width

Claims (5)

A tire case including a carcass extending from one bead portion to the other bead portion, and at least the outer portion of the carcass in the tire width direction is coated with a first rubber material.
A tread made of a second rubber material arranged on the outer side of the tire case in the tire radial direction,
It is molded separately from the tire case, placed between the tire case and the tread, and vulcanized and bonded to the tire case and the tread, and the cord is attached to the first rubber material and the first rubber material. A resin-coated cord formed by coating with a resin having a tensile elasticity higher than that of the rubber material of No. 2 is spirally wound, and one of the resins adjacent to the tire width direction when viewed in the tire width direction cross section. A single-layer belt in which the resin of the coating cord and the resin of the other resin coating cord are integrally bonded.
Pneumatic tires with. The pneumatic tire according to claim 1, wherein the resin-coated cord has an inner peripheral surface on the carcass side and an outer peripheral surface on the tread side displaced in the belt width direction. The pneumatic tire according to claim 1 or 2, further comprising a fiber or cord and provided with a layer covering the end of the belt. A resin layer made of the first rubber material and a resin having a tensile elastic modulus larger than that of the second rubber material is arranged on the inner peripheral surface of the belt in the tire radial direction.
The pneumatic tire according to any one of claims 1 to 3, wherein the resin layer is integrally bonded to the resin coated with the cord. The pneumatic tire according to any one of claims 1 to 4, wherein the width measured along the tire width direction of the belt is set to 75% or more of the ground contact width of the tread.