JP6577221B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire (hereinafter, also simply referred to as “tire”), and more particularly, to a pneumatic tire that is excellent in lightness and durability and has improved workability during tire manufacture.

  In recent years, there has been an increasing demand for lighter tires in order to improve the fuel efficiency of automobiles. Conventionally, in order to reduce the weight of tires, a technology that uses a steel cord as a belt cord without twisting steel monofilament is known instead of a twisted cord in which a plurality of steel filaments are twisted as a belt cord. A cross belt has been developed in which at least two belt layers are arranged so as to cross each other. When the belt cord is made into a monofilament in this way, the belt layer can be thinned, and the weight of the tire can be reduced.

  However, when a belt layer made of steel monofilament is used, there is a problem that the bending rigidity in the belt surface (in-plane bending rigidity) is lowered, and the durability of the tire is lowered. Therefore, in Patent Document 1, a pneumatic radial tire for a passenger car provided with a belt auxiliary layer made of a steel cord embedded at an angle of 80 to 90 ° with respect to the tire circumferential direction in order to compensate for the insufficient in-plane bending rigidity. Has been proposed. According to Patent Document 1, by providing the belt auxiliary layer, it is possible to suppress the buckling of the belt cord and to compensate the fatigue property against bending that is reduced due to monofilament formation.

JP 2012-254668 A

  However, if a belt reinforcing layer made of steel cord is provided, the amount of steel used increases, leading to an increase in tire weight. Therefore, in the tire described in Patent Document 1, the advantage of reducing the weight of the tire by configuring the cross belt with a belt layer made of steel monofilament cannot be fully utilized, and the weight reduction of the tire is not always satisfactory. This is not the case. Further, in the manufacture of tires, improvement in workability is desired.

  Accordingly, an object of the present invention is to provide a pneumatic tire which is excellent in lightness and durability and has improved workability at the time of tire manufacture.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by setting the reinforcing elements of the carcass and the belt reinforcing layer to be predetermined, and the present invention is completed. It came to.

That is, in the pneumatic tire of the present invention, a belt layer in which a plurality of steel monofilaments arranged without being twisted are embedded in rubber on the outer side in the tire radial direction of the carcass intersects with each other between the layers. In a pneumatic tire provided with a cross belt arranged in at least two layers
Comprising at least one belt reinforcing layer in which a reinforcing element is embedded in rubber in at least one of a tire radial direction outer side, a tire radial direction inner side, and a cross belt layer of the cross belt,
An angle of the steel monofilament of the cross belt with respect to the tire circumferential direction is 45 ° or more, and the steel monofilament has at least two different diameters,
The number of driven steel filaments of the cross belt is 26 to 100/50 mm,
The reinforcing element of the belt reinforcing layer is an organic fiber cord.

In the tire of the present invention, among the at least two types of steel monofilaments, when the wire diameter of the steel filament having the largest wire diameter is d1, and the wire diameter of the steel filament having the smallest wire diameter is d2, the following formula:
1 <d1 / d2 <4
It is preferable to satisfy the relationship represented by these. In the tire of the present invention, the reinforcing element of the belt reinforcing layer is preferably an organic fiber cord made of at least one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, nylon, polyketone and aramid. Furthermore, in the present invention, the angle of the reinforcing element of the belt reinforcing layer with respect to the tire circumferential direction is preferably 0 to 10 °. Furthermore, in the pneumatic tire of the present invention, it is preferable that the steel monofilament is straight.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which was excellent in the lightness and durability, and improved the workability | operativity at the time of tire manufacture can be provided.

1 is a cross-sectional view in the width direction of a pneumatic tire according to a preferred embodiment of the present invention. It is a schematic plan view which shows the relationship between the belt layer and belt reinforcement layer of the pneumatic tire which concerns on one preferable embodiment of this invention. 1 is a cross-sectional view in the tire width direction of a cross belt and a belt reinforcing layer of a pneumatic tire according to a preferred embodiment of the present invention.

Hereinafter, the pneumatic tire of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view in the width direction of a pneumatic tire according to a preferred embodiment of the present invention. As shown in the drawing, a tire 10 of the present invention includes a tread portion 1 that forms a ground contact portion, a pair of sidewall portions 2 that extend inward in the tire radial direction continuously to both sides of the tread portion 1, and each side. And a bead portion 3 continuous on the inner peripheral side of the wall portion 2. The tread portion 1, the sidewall portion 2, and the bead portion 3 are reinforced by a carcass 4 including a single carcass ply extending in a toroidal shape from one bead portion 3 to the other bead portion 3.

  In the tire 10 of the present invention, at least two layers (two layers in the illustrated example), preferably two layers of the first belt layer 5a and the second belt layer 5b, are formed on the outer side of the crown region of the carcass 4 in the tire radial direction. A belt is provided. The first belt layer 5a and the second belt layer 5b are formed by embedding a plurality of steel monofilaments arranged in parallel in the tire width direction without being twisted in the rubber. The two belt layers 5b are arranged so as to intersect with each other between the layers to form the intersecting belt 5.

  In the tire 10 of the present invention, the angle of the steel monofilament of the cross belt 5 with respect to the tire circumferential direction is 35 ° or more. By disposing the steel monofilament at a high angle with respect to the tire circumferential direction, in-plane bending rigidity can be imparted to the cross belt 5 and the durability and wear resistance of the tire 10 can be ensured. Preferably, the angle of the steel monofilament with respect to the tire circumferential direction is 45 ° or more.

  Further, the tire 10 of the present invention has a belt reinforcing layer at least at one position (in the illustrated example, the outer side in the tire radial direction of the cross belt 5) among the outer side in the tire radial direction, the inner side in the tire radial direction, and the cross belt layer. 6. The angle of the reinforcing element of the belt reinforcing layer 6 is preferably 0 ° to 10 ° with respect to the tire circumferential direction because the purpose is to supplement the tensile stiffness in the tire circumferential direction, which is insufficient for that purpose. FIG. 2 is a schematic plan view showing a relationship between a belt layer and a belt reinforcing layer of a pneumatic tire according to a preferred embodiment of the present invention. FIG. 2 (a) is a tire in which the belt reinforcing layer 6 is a cross belt 5. In (b), the belt reinforcement layer 6 is disposed on the inner side in the tire radial direction of the cross belt 5, and in (c), the belt reinforcement layer 6 is disposed between the cross belt layers 5a and 5b.

  Furthermore, in the tire 10 of the present invention, the steel monofilaments of the cross belt 5 are at least two types having different diameters. FIG. 3 shows a cross-sectional view in the tire width direction of a crossing belt and a belt reinforcing layer of a pneumatic tire according to a preferred embodiment of the present invention. As shown in the figure, the distance between adjacent steel filaments can be changed randomly by using steel filaments having different wire diameters. Thereby, both rigidity and durability of the belt can be achieved.

  Focusing on the cross belt 5, the distance L1 between the steel filaments 7a having a large wire diameter is the distance L2 between the steel filament 7a having a large wire diameter and the steel filament 7b having a small wire diameter, or the distance between the steel filaments 7b having a small wire diameter. It is narrower than L3. The rigidity of the belt can be maintained by the presence of a portion having a narrow interval between the steel filaments at random. In addition, the belt edge separation (BES) in which rubber peeling starting from the steel filament end of the belt width direction end easily propagates between the adjacent steel filaments is possible because there is a portion where the distance between the steel filaments is randomly present. Can be suppressed.

  When attention is paid to the belt reinforcing layer 6 and the belt layer adjacent to the belt reinforcing layer 6 (second belt layer 5b in the illustrated example), the steel filament 7b having a thin wire diameter embedded in the second belt layer 5b and the belt A distance L4 between the reinforcing element embedded in the reinforcing layer 6 (in the illustrated example, the organic fiber cord 6) is wider than a distance L5 between the steel filament 7a having a large wire diameter and the organic fiber cord 6 of the belt reinforcing layer 6. . Accordingly, a wide area appears randomly in the interval between the reinforcing elements of the second belt layer 5b and the belt reinforcing layer 6. Therefore, the crack of rubber propagating between the steel filaments can be suppressed.

  Furthermore, by adding a steel filament having a large wire diameter as a reinforcing element of the cross belt 5, the workability of the belt treat is improved as compared with the case of a steel filament having a thin wire diameter. That is, only with the steel filament 7b having a thin wire diameter is difficult to determine because the bending rigidity of the belt treat is insufficient, but by including the steel filament 7a with a large wire diameter, the bending rigidity of the belt treat increases. As a result, the workability of the decency work is improved.

In the tire 10 of the present invention, in order to obtain the above effect satisfactorily, among the at least two types of steel monofilaments, the wire diameter of the steel filament with the largest wire diameter is d1, and the wire diameter of the steel filament with the smallest wire diameter is Where d2 is the following formula:
1 <d1 / d2 <4
It is preferable to satisfy the relationship represented by these. Preferably,
1.1 <d1 / d2 <2
It is. When d1 / d2 is larger than 4, the cross belt 5 becomes thick, and the effect of using a steel monofilament as a reinforcing element may not be sufficiently obtained.

  Furthermore, in the tire 10 of the present invention, the ratio of the steel filament having a large wire diameter to the total steel filament is preferably 10% or more. The said effect can be acquired favorably by making a steel filament with a big wire diameter into 10% or more. In addition, in order to acquire the effect of this invention satisfactorily, the ratio of the steel filament with a large wire diameter is preferably 80% or less.

  Moreover, in the tire 10 of the present invention, it is preferable that the number of driven steel filaments of the cross belt 5 is 26 to 100/50 mm. If the number of steel monofilaments to be driven is 26/50 mm or more, sufficient in-plane bending rigidity can be ensured. Further, by setting the number of steel monofilaments to be driven to 100/50 mm or less, rubber edge separation starting from the cord end at the end in the belt width direction can easily suppress belt edge separation (BES) that propagates between adjacent cords. BES resistance can be exhibited. The suitable range which can maintain these balance favorably is 40-55 piece / 50mm.

  In the tire 10 of the present invention, the reinforcing element of the belt reinforcing layer 6 is preferably an organic fiber cord. By using a cord made of organic fiber as the reinforcing element, the weight of the tire can be reduced as compared with the case where steel is used. In the tire 10 of the present invention, the reinforcing element constituting the belt reinforcing layer 6 is intended to ensure tensile rigidity in the tire circumferential direction, and therefore, a cord made of highly elastic organic fibers is preferably used. Organic fiber cords include aromatic polyamide (aramid), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), rayon, Zylon (registered trademark) (polyparaphenylene benzobisoxazole (PBO) fiber), aliphatic polyamide ( Nylon), polyketone, and other organic fibers can be used.

  In the tire 10 of the present invention, when the organic fiber cord 8 is used as the reinforcing element of the belt reinforcing layer 6, the total fineness of the organic fiber cord 8 is preferably 470 to 5000 dtex. By setting the total fineness of the organic fiber cord 8 to 470 dtex or more, the circumferential tensile rigidity of the belt reinforcing layer 6 can be sufficiently ensured. On the other hand, the total fineness of the organic fiber cord 8 is preferably 5000 dtex or less. By setting the total fineness to 5000 dtex or less, the belt reinforcing layer 6 can be thinned, and both the circumferential tensile rigidity and the weight reduction can be achieved. In the tire 10 of the present invention, the organic fiber cord 8 may be either a single twist or a double twist or a twisted cord in which three or more are twisted together. In this case, the upper twist coefficient is desirably 0.05 to 0.8.

  In the tire 10 of the present invention, when the belt reinforcing layer 6 is inserted between the layers of the cross belt 5 or when the belt reinforcing layer 6 is disposed inside the cross belt 5 in the tire radial direction, the cross belt layer made of steel monofilament. (In the illustrated example, the second belt layer 5b) plays the role of a protective layer, so that the cut resistance can be improved.

  In the tire 10 of the present invention, the width of the belt reinforcing layer 6 is preferably 60% or more of the tread width. By setting the width of the belt reinforcing layer 6 to 60% or more of the tread width, the tensile rigidity in the tire circumferential direction can be effectively improved. Preferably, the belt reinforcing layer 6 is disposed over the entire tread width. The tread width is the maximum width in the tire axial direction of the tire contact surface when a tire is mounted on a regular rim, filled with a regular internal pressure, placed perpendicular to the flat plate in a stationary state, and a regular load is applied. Say.

  Furthermore, although the belt reinforcing layer 6 of the tire shown in FIG. 1 covers the entire width of the tread (so-called cap structure), it may be a structure that covers only both ends in the width direction of the cross belt 5 (so-called layer structure). Further, the first belt reinforcing layer may be provided so as to cover at least the center of the cross belt 5 in the width direction, and the second belt reinforcing layer may be provided so as to cover both ends of the cross belt 5 in the width direction (cap layer). Construction). In this case, the second belt reinforcement layer may be provided until the vicinity of the first belt reinforcement layer, or continuously or intermittently until they overlap. Further, in the belt reinforcing layer 6, reinforcing elements may be arranged at intervals with respect to the groove below the tread according to the shape of the tread.

  Furthermore, in the tire 10 of the present invention, it is preferable that the wire diameter of the steel monofilament 7 constituting the cross belt 5 is 0.12 to 0.45 mm. By setting the wire diameter of the steel monofilament 7 to 0.12 mm or more, the in-plane bending rigidity of the cross belt 5 can be sufficiently secured. On the other hand, by setting the wire diameter of the steel monofilament 7 to 0.45 mm or less, an increase in the thickness of the belt layer can be prevented, and both in-plane bending rigidity and weight reduction of the belt layer can be achieved. More preferably, it is 0.25 to 0.35 mm.

  Furthermore, it is preferable that the steel monofilament 7 constituting the cross belt 5 and the organic fiber cord 8 constituting the belt reinforcing layer 6 have straightness that is not shaped. This is because a straight cord does not have initial elongation, so that sufficient rigidity can be obtained immediately after input from the outside.

  In the tire 10 of the present invention, the steel monofilaments constituting the first belt layer 5a and the second belt layer 5b are preferably at an angle symmetrical to the tire circumferential direction. By adopting such a configuration, the productivity of the tire is improved and the stress can be shared equally, which is preferable from the viewpoint of the durability of the tire.

  In the tire 10 of the present invention, the number of driven reinforcing elements of the carcass 4 and the reinforcing elements of the belt reinforcing layer 6 is preferably 20 to 80/50 mm. By setting the number of drivings to 20/50 mm or more, the tensile rigidity in the tire circumferential direction can be sufficiently secured. Moreover, the tensile rigidity of a tire circumferential direction and BES resistance can be made compatible by making the number of driving | running | working into 80 pieces / 50mm or less. The carcass 4 is usually composed of at least one layer (in the illustrated example, one layer) of carcass plies made of a plurality of organic fiber cords arranged at a cord angle of 70 ° to 90 ° with respect to the tire equatorial plane. However, the present invention is not limited to this, and it may be composed of two or more carcass plies. An organic fiber cord can be used as the reinforcing element of the carcass 4, and the organic fiber cord can be a single twist cord, a double twist cord, or three or more multiple twist cords.

  In the tire 10 of the present invention, it is only important to satisfy the above-described configuration, and a known structure can be adopted as the other structure. For example, as shown in the figure, a bead core 9 is embedded in each of the pair of bead portions 3 of the tire of the present invention, and the carcass 4 is folded and locked around the bead core 9 from the inside to the outside of the tire. The bead core 9 may be wound and locked, or may be sandwiched and locked with bead wires from both sides (not shown), and any fixing method may be used.

  Furthermore, in the tire 10 of the present invention, a tread pattern may be appropriately formed on the surface of the tread portion 1, and an inner liner (not shown) may be formed in the innermost layer. Further, in the tire 10 of the present invention, as the gas filled in the tire, normal or air having a changed oxygen partial pressure, or an inert gas such as nitrogen can be used. The tire of the present invention is suitable for a pneumatic tire for passenger cars.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Examples 1 to 10, Comparative Example>
A tire of the type shown in FIG. 1 was produced with a tire size of 145 / 65R15. Tables 1 to 3 below show the wire diameter and wire diameter ratio of the steel filament constituting the cross belt, the material of the belt reinforcing layer, and the number of driven-in wires. Steel filaments, which are reinforcing elements for the cross belts, had a steel wire with a large wire diameter of 50% of all the steel filaments, a belt angle of 45 °, and the number of driven wires of 45/50 mm. The belt reinforcing layer was substantially parallel to the tire circumferential direction, the twisted structure was 2200 dtex / 2, and the number of driven-in was 42/50 mm. On the other hand, the cross belt of the conventional example is 1 × 3, the driving is 30 pieces / 50 mm, and no belt reinforcing layer element is provided.

<Lightweight>
When the weight per tire was measured and the tire of the comparative example was used as a reference, the case where the weight could be reduced by less than 50 g than the comparative example was marked with ◯, and the case where the weight was reduced by 50 g or more was marked with ◎. The results are shown in Tables 1-3.

<BES resistance>
Each tire is mounted on a regular rim specified by JATMA, loaded with 1.2 times the normal load, filled with 210 kPa of internal pressure, run for 40,000 km, then dissected the tire, and belt layer The length of the crack (separation length) generated at the end was measured. When the tire of the conventional example was used as a reference (index: 100), the case of 120 or more was indicated by Δ, the case of 80 to 119 was indicated by ◯, and the case of less than 80 was indicated by ◎. The results are shown in Tables 1-3.

<Decisive workability>
On the basis of the workability of the belt treat in the manufacture of the tire of the comparative example, the case where the workability is equivalent is marked with ◯, and the case where the workability is improved is marked with ◎. The results are shown in Tables 1-3.

※：スチールモノフィラメント

*: Steel monofilament

  From the above Tables 1 to 3, it can be seen that the tire of the present invention is excellent in lightness and durability, and the workability at the time of manufacturing the tire can be improved.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass 5 Crossing belt 5a 1st belt layer 5b 2nd belt layer 6 Belt reinforcement layer 7 Steel filament 8 Organic fiber cord 9 Bead core 10 Pneumatic tire (tire)

Claims (5)

A cross belt in which at least two layers of a belt layer in which a plurality of steel monofilaments arranged without being twisted are embedded in rubber are arranged on the outer side in the tire radial direction of the carcass so as to cross each other. In a pneumatic tire comprising:
Comprising at least one belt reinforcing layer in which a reinforcing element is embedded in rubber in at least one of a tire radial direction outer side, a tire radial direction inner side, and a cross belt layer of the cross belt,
An angle of the steel monofilament of the cross belt with respect to the tire circumferential direction is 45 ° or more, and the steel monofilament has at least two different diameters,
The end count of the steel filaments of the cross belt Ri 26-100 present / 50 mm der,
A pneumatic tire reinforcing elements of the belt reinforcing layer, characterized in Rukoto Oh organic fiber cord. Of the at least two types of steel monofilaments, when the wire diameter of the steel filament having the largest wire diameter is d1, and the wire diameter of the steel filament having the smallest wire diameter is d2, the following formula:
1 <d1 / d2 <4
The pneumatic tire according to claim 1, satisfying a relationship represented by:   The pneumatic tire according to claim 1 or 2, wherein the reinforcing element of the belt reinforcing layer is an organic fiber cord made of at least one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, nylon, polyketone and aramid.   The pneumatic tire according to any one of claims 1 to 3, wherein an angle of the reinforcing element of the belt reinforcing layer with respect to a tire circumferential direction is 0 to 10 °.   The pneumatic tire according to any one of claims 1 to 4, wherein the steel filament is straight.

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