JP6203597B2 - 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 realizes lightness, durability, and wear resistance at a high level.

  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 a steel monofilament is used, there is a problem that the bending rigidity (in-plane bending rigidity) in the belt surface is lowered, and the durability and wear resistance of the tire are 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.

  Accordingly, an object of the present invention is to provide a pneumatic tire in which lightness, durability, and wear resistance are realized in a high dimension.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by making the belt layer and the belt auxiliary layer have a predetermined structure, thereby completing the present invention. It came to.

That is, the tire of the present invention has at least two layers such that a belt layer in which a plurality of steel monofilaments arranged in parallel in the tire width direction without being twisted are embedded in rubber intersects each other between the layers. A cross belt formed, and at least one belt reinforcing layer in which a reinforcing element is embedded at an angle of 0 to 10 ° with respect to the tire circumferential direction on the inner side or the outer side in the tire radial direction of the cross belt. In pneumatic tires,
The number of driven steel monofilaments in the belt layer is 26 to 100/50 mm, the angle of the steel monofilament with respect to the tire circumferential direction is 35 ° or more, and the reinforcing element of the belt reinforcing layer is organic Made of fiber cord,
When the interlayer rubber gauge of the at least two belt layers is h1, and the interlayer rubber gauge between the belt layer and the belt reinforcing layer is h2, the following formula (1):
h1> h2 (1)
It is characterized by satisfying the relationship represented by

In the tire of the present invention, the thickness of each belt layer of the at least two belt layers is S (mm), the diameter of the steel monofilament is s (mm), and the thickness of the belt reinforcing layer is T (mm). When the diameter of the organic fiber cord is t (mm), the following formula (2),
1.24 <(T + S) / (t + s) <3.63 (2)
It is preferable to satisfy the relationship represented by these.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which implement | achieved lightweight, durability, and abrasion resistance in the high dimension can be provided.

1 is a tire width direction cross-sectional view of a tire according to a preferred embodiment of the present invention. 1 is a partial cross-sectional view of a cross belt and a belt reinforcing layer of a tire according to a preferred embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a tire width direction sectional view of a pneumatic tire according to a preferred embodiment of the present invention. The illustrated tire 10 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 side portions of the tread portion 1, and an inner periphery of each sidewall portion 2. And a bead portion 3 continuous on the side. 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 5 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 each other between the layers to form a cross belt.

  In the tire 10 of the present invention shown in the drawing, the number of steel monofilaments driven in the first belt layer 5a and the second belt layer 5b is 26 to 100/50 mm. By setting the number of steel monofilaments to be 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.

  Further, in the illustrated tire 10 of the present invention, the angle of the steel monofilaments of the belt layers (the first belt layer 5a and the second belt layer 5b) is 35 ° or more with respect to the tire circumferential direction. By arranging the steel monofilament at a high angle with respect to the tire circumferential direction, in-plane bending rigidity is imparted to the cross belt 5, and the durability and wear resistance of the tire 10 are ensured. Preferably, the angle of the steel monofilament with respect to the tire circumferential direction is 45 ° or more.

  Further, the tire 10 according to the present invention includes at least one belt in which reinforcing elements are embedded at an angle of 0 to 10 ° with respect to the tire circumferential direction on the inner side or the outer side (outer side in the illustrated example) of the cross belt 5 in the tire radial direction. A reinforcing layer 6 is embedded. Since the belt layers of the tire of the present invention (the first belt layer 5a and the second belt layer 5b in the illustrated example) have an angle of 35 ° or more with respect to the tire circumferential direction, the tensile stiffness in the tire circumferential direction is Not enough. Therefore, the belt reinforcing layer 6 compensates for insufficient tensile rigidity in the tire circumferential direction.

  Furthermore, in the tire of the present invention, the reinforcing element of the belt reinforcing layer 6 is made of 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) or the like can be used.

FIG. 2 is a partial cross-sectional view of a cross belt and a belt reinforcing layer of a tire according to a preferred embodiment of the present invention. In the tire 10 of the present invention, at least two belt layer interlayer rubber gauges (in the illustrated example, the rubber gauges of the first belt layer 5a and the second belt layer 5b) are h1, and the interlayer rubber gauge between the belt layer and the belt reinforcing layer (see FIG. In the example shown, when the rubber gauge of the second belt layer 5b and the belt reinforcing layer 6 is h2, the following formula (1),
h1> h2 (1)
It is preferable to satisfy the relationship represented by these.

  Since the tire 10 of the present invention has the cross belt 5 at a high angle, the in-plane bending rigidity is high. Therefore, high grounding performance can be ensured during cornering. However, at the cornering limit, it cannot withstand the lateral force of the tire and causes belt buckling. At this time, if the gauge of h1 becomes thinner than h2, the out-of-plane bending rigidity is lowered and the belt buckling curvature is increased. As a result, the durability of the cross belt 5 may be reduced. Therefore, the fatigue resistance can be improved by making the rubber gauge between the intersecting first belt layer 5a and the second belt layer 5b larger than the rubber gauge between the belt reinforcing layer 6 and the second belt layer. Further, since the cross belt 5 has high in-plane bending rigidity, the shear strain generated during cornering is concentrated between the cross belt layers, and the shear strain between the belt layer and the belt reinforcement layer is small. Therefore, h2 can be made thinner than h1, and the weight of the tire can be reduced.

In the tire 10 of the present invention, the thickness of the belt layers (first belt layer 5a and second belt layer 5b in the illustrated example) is S (mm), the diameter of the steel monofilament 7 is s (mm), and the belt is reinforced. When the thickness of the layer 6 is T (mm) and the diameter of the organic fiber cord 8 is t (mm) (see FIG. 2), the following formula (2),
1.24 <(T + S) / (t + s) <3.63 (2)
It is preferable to satisfy the relationship represented by these. Here, T = 0.5 to 2.0, t = 0.2 m to 1.8, S = 0.66 to 1.2, and s = 0.12 to 0.45. By setting (T + S) / (t + s) to be 1.25 or more, belt edge separation (BES) in which the interlayer gauge is maintained and rubber peeling starting from the cord end of the belt width direction end portion easily propagates between adjacent cords. ) Can be satisfactorily prevented. On the other hand, when the amount is 3.63 or less, the amount of rubber used can be reduced, and both belt edge separation resistance (hereinafter referred to as “BES resistance”) and light weight can be achieved.

  Furthermore, 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, in the tire 10 of the present invention, the number of driven organic fiber cords 8 in the belt reinforcing layer 6 is preferably 20 to 80/50 mm. By setting the number of driving to 20 or more, sufficient tensile rigidity in the tire circumferential direction can be ensured. On the other hand, by setting the number of drivings to 80/50 mm or less, both the tensile rigidity in the tire circumferential direction and the BES resistance can be achieved.

  In the tire 10 of the present invention, the total fineness of the organic fiber cord 8 in the belt reinforcing layer 6 is preferably 500 to 8000 dtex. By setting the total fineness of the organic fiber cord to 500 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 8000 dtex or less. By setting the total fineness to 8000 dtex or less, the belt reinforcing layer 6 can be thinned, and both the circumferential tensile rigidity and the weight reduction can be achieved.

  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 subjected to any type. This is because a straight cord does not have initial elongation, so that sufficient rigidity can be obtained immediately after input from the outside.

  Furthermore, in the tire 10 of the present invention, it is preferable that the intervals between the steel monofilaments 7 are equal. By making the intervals between the steel filaments 7 uniform, the manufacture of the belt treat is facilitated and the productivity is improved. Further, since there is no extremely narrow portion between the steel filaments 7, the BES resistance is excellent.

  In the illustrated tire 10 of the present invention, the steel monofilaments constituting the first belt layer 5a and the second belt layer 5b are preferably symmetric with respect 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, a belt layer formed by embedding a plurality of steel monofilaments arranged in parallel in the tire width direction without being twisted in the tire radial direction outside the carcass 4 is interposed between the layers. Cross belt 5 that is arranged in at least two layers so as to cross each other, and at least one in which reinforcing elements are embedded at an angle of 0 to 10 ° with respect to the tire circumferential direction inside or outside the cross belt 5 in the tire radial direction. Belt reinforcing layers 6, and the number of steel monofilaments driven in the belt layers (in the illustrated example, the first belt layer 5 a and the second belt layer 5 b) constituting the cross belt 5 is 26 to 100/50 mm. The angle of the steel monofilament with respect to the tire circumferential direction is 35 ° or more, and the reinforcing element of the belt reinforcing layer 6 is an organic fiber. It is only important that the cord is made of a fiber cord, and a known structure can be adopted for other structures.

  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 around the bead core 9 from the inside to the outside and locked. Further, a tread pattern is appropriately formed on the surface of the tread portion 1, and an inner liner (not shown) is 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 pneumatic 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 1-8, Comparative Examples 1-4>
A tire of the type shown in FIG. 1 was produced with a tire size of 145 / 65R15. The cross belt 5 includes two belt layers 5a and 5b. Table 1 shows the wire diameter, the number of driven steel filaments, and the angle with respect to the tire circumferential direction. In Examples 1 to 8 and Comparative Examples 1 to 3, the belt reinforcing layer 6 is one layer, an aramid cord (1670 dtex / 3) having a total fineness of 5010 dtex is used, and the tire circumferential direction is substantially the entire width in the tread width direction. Arranged to be parallel. In Comparative Example 4, the belt reinforcing layer was omitted. Tables 1 to 3 show rubber gauges h1 of the first belt layer 5a and the second belt layer 5b, rubber gauges h2 of the second belt layer 5b and the belt reinforcing layer 6, and (T + S) / (t + s).

<Conventional example>
Tire size: A pneumatic tire having an intersecting belt composed of two belt layers and a belt reinforcing layer on the outer side in the tire radial direction of the intersecting belt was manufactured at 145 / 65R15. The cross belt is a steel cord having a 1 × 3 structure made of steel filaments having a wire diameter of 0.30 mm. The number of driven wires and the angle with respect to the tire circumferential direction are as shown in Table 1. Further, Conventional Example 1 has no belt reinforcing layer, Conventional Example 2 has one belt reinforcing layer, uses an aliphatic polyamide (nylon) cord having a total fineness of 2880 dtex (1440 dtex / 2), and is substantially parallel over the entire width of the tread width. Arranged to be. Table 3 shows the rubber gauge h1 of the first belt layer and the second belt layer, the rubber gauge h2 of the second belt layer and the belt reinforcing layer, and (T + S) / (t + s).

  About each obtained tire, tire weight, belt fatigue resistance, BES resistance, and abrasion resistance were evaluated according to the following procedures.

<Tire weight>
The weight per tire was measured, and the case where it was lighter than the tire of Conventional Example 1 was negative, and the case where it was increased was positive. The results are shown in Tables 1-3.

<Belt fatigue resistance>
In a vehicle equipped with an autopilot that can run in figure 8 with each tire assembled to a regular rim specified by JATMA, loaded with 1.05 times the normal load, filled with an internal pressure of 100 kPa After running the figure 8 turning test course at a turning acceleration of 0.7 G, a speed of 25 km / h and 300 laps, the tires were dissected and evaluated for belt breakage. The cord breakage rate of each tire is indicated by an index with the tire of Conventional Example 1 as 100. The smaller this value, the better the belt folding resistance. The results are shown in Tables 1-3.

<BES resistance>
Each tire is mounted on a regular rim prescribed by JATMA, loaded with twice the normal load, filled with 210 kPa of internal pressure, traveled for 20,000 km, then dissected the tire, and the belt layer end The length of the crack (separation length) generated in the film was measured. The crack length of each tire is indicated by an index with the crack length of the tire of Conventional Example 1 being 100. The smaller this value, the better the BES resistance. The results are shown in Tables 1-3.

<Abrasion resistance>
Each tire is mounted on an actual vehicle, and the remaining tire groove depth (center rib groove) after actual vehicle endurance travel (running an existing circuit of 3.5 km per lap for 20 laps in the limit travel mode) is measured. The tire was evaluated as an index. The smaller this value, the better the wear resistance. The results are shown in Tables 1-3.

  From Tables 1-3, it turns out that the pneumatic tire of this invention is excellent in durability, abrasion resistance, and lightweight property.

1 Tread part 2 Side wall part 3 Bead part 4 Carcass 5 Belt (cross belt)
6 Belt reinforcement layer 7 Steel monofilament 8 Organic fiber cord 9 Bead core 10 Pneumatic tire

Claims (2)

A belt layer in which a plurality of steel monofilaments arranged in parallel in the tire width direction without being twisted are embedded in rubber, and an intersecting belt in which at least two layers are arranged so as to intersect each other between the layers, In a pneumatic tire comprising: at least one belt reinforcing layer in which reinforcing elements are embedded at an angle of 0 to 10 ° with respect to the tire circumferential direction on the inner side or the outer side of the cross belt in the tire radial direction;
The number of driven steel monofilaments in the belt layer is 26 to 100/50 mm, the angle of the steel monofilament with respect to the tire circumferential direction is 35 ° or more, and the reinforcing element of the belt reinforcing layer is organic fiber code Tona is,
When the interlayer rubber gauge of the at least two belt layers is h1, and the interlayer rubber gauge between the belt layer and the belt reinforcing layer is h2, the following formula (1):
h1> h2 (1)
A pneumatic tire characterized by satisfying the relationship expressed by: The thickness of each belt layer of the at least two belt layers is S (mm), the diameter of the steel monofilament is s (mm), the thickness of the belt reinforcing layer is T (mm), and the diameter of the organic fiber cord Is t (mm), the following formula (2),
1.24 <(T + S) / (t + s) <3.63 (2)
The pneumatic tire of claim 1 satisfies the relationship in represented.

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