JP6577345B2 - 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 in which steering stability and ride comfort are both highly compatible.

  Today, in a pneumatic tire, it is known to increase the rigidity of the sidewall portion from the bead portion as a method for improving the steering stability. For example, a configuration in which a reinforcement member that includes a bead core and a bead filler from the bead portion to the sidewall portion, a so-called flipper, a configuration in which a so-called insert reinforcement layer is disposed from the bead portion to the sidewall portion, and the like are widely known. .

  For example, Patent Document 1 proposes a pneumatic tire for a passenger car using a rubber-steel cord composite having a predetermined structure and excellent in elasticity and bending rigidity as an insert reinforcing layer. Since the tire proposed in Patent Document 1 has an insert reinforcing layer in the sidewall portion, the amount of deflection of the sidewall portion is small and heat generation is small. Therefore, even during running, particularly run-flat running, the adhesiveness between the rubber and the reinforcing cord does not decrease, and the durability in the normal running at the time of filling with the internal pressure is not impaired.

JP 2000-25423 A

  However, when the insert reinforcing layer is disposed, the rigidity in the vertical direction of the tire is also increased, which causes another problem that ride comfort is deteriorated. Ride comfort is particularly important when driving on uneven and stepped road surfaces. When an insert is placed from the bead to the sidewall, the size of the bump (shock) over the step and its fit (dumping) Will greatly deteriorate. Therefore, it is difficult to achieve both steering stability and riding comfort, and further investigation is necessary.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire that is highly compatible with handling stability and riding comfort.

  As a result of intensive studies to solve the above problems, the present inventor has found that the in-plane bending rigidity of the insert reinforcing layer affects the steering stability, and the out-of-plane bending rigidity affects the riding comfort. It came to complete.

That is, the pneumatic tire according to the present invention includes a pair of left and right bead portions, a sidewall portion connected to the radially outer side of the bead portion, a tread portion straddling the sidewall portions, and the pair of left and right bead portions. Air having a carcass formed of at least one carcass ply extending in a toroid shape, and at least one insert reinforcing layer disposed in at least a part of a region from the bead portion to a shoulder portion of the tread portion. In entering tires,
The reinforcing material of the insert reinforcing layer consists of a steel cord and a cord other than a steel cord,
The ratio of cords other than steel cords in the reinforcing material is 10 to 48%. Here, the in-plane bending rigidity is expressed by a first-order differential component (ΔFxi / ΔXi) when defined as an in-plane deformation ΔXi of the insert reinforcing layer and a force ΔFxi acting at that time. The out-of-plane bending stiffness is expressed as a first-order differential component (ΔFyi / Δyi), where ΔYi is the amount of deformation that deforms in a direction perpendicular to the insert cord direction (out-of-plane) and the force ΔFyi acting at that time.

  In the tire of the present invention, the steel cord is preferably a steel monofilament. Moreover, in the tire of this invention, it is preferable that the in-plane bending rigidity of the said insert reinforcement layer is 14 to 34 times the out-of-plane bending rigidity of the said insert reinforcement layer. Furthermore, in the tire of the present invention, it is preferable that the reinforcing material of the insert reinforcing layer is arranged at 0 ° to 70 ° with respect to the radial direction.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which made the steering stability and riding comfort highly compatible 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.

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, the tire 10 of the present invention includes a pair of left and right bead portions 1, a sidewall portion 2 that continues to the outside in the radial direction of the bead portion 1, a tread portion 3 that straddles between the sidewall portions 2, and a pair of left and right portions. A carcass 4 made of at least one carcass ply extending in a toroidal shape is provided between the bead portions 1. In the illustrated tire 10, a bead core 5 is embedded in each bead portion 1, and a bead filler 6 is disposed between the main body portion 4 a and the folded portion 4 b of the carcass 4 on the outer side in the tire radial direction. ing. Further, in the tire of the present invention, the belt 7 composed of at least one layer (two layers in the illustrated example) of the belt layers 7 a and 7 b is provided on the outer side in the radial direction of the carcass 4, and the shoulder portion of the tread portion 3 from the bead portion 1. At least a part of the insert reinforcing layer 8 is disposed in at least a part of the region up to this point.

  In the tire 10 of the present invention, the reinforcing material of the insert reinforcing layer 8 is composed of a steel cord and a cord other than the steel cord. In the tire having the insert reinforcing layer 8, the in-plane bending rigidity of the insert reinforcing layer 8 affects the steering stability, and the out-of-plane bending rigidity affects the riding comfort. That is, the driving stability can be improved by increasing the in-plane bending rigidity, and the riding comfort can be maintained by suppressing the out-of-plane bending rigidity. Therefore, a steel cord and a cord other than the steel cord are used as a reinforcing material for the insert reinforcing layer 8. Examples of cords other than steel cords include cords made of organic fibers and cords made of inorganic fibers other than steel. Cords other than this steel cord contribute to the in-plane rigidity but do not greatly contribute to the out-of-plane rigidity, so that both steering stability and riding comfort can be achieved. Moreover, since the insert reinforcement layer 8 is reduced in weight by using cords other than steel cords, the effect of improving rolling resistance can be obtained.

The steel cord of the insert reinforcing layer 8 according to the tire 10 of the present invention is preferably a steel monofilament from the viewpoint of reducing the weight of the tire, but may be a twisted cord having a single twist structure or a layer twist structure. In this case, it is preferable to use a steel filament having a tensile strength of 2700 N / mm ² or more. As the steel filament having a high tensile strength, one containing at least 0.72% by mass, particularly at least 0.82% by mass of carbon can be suitably used. In addition, when using a twisted cord as the steel cord, conditions such as a twisting direction and a twisting pitch are not particularly limited, and can be appropriately configured according to a conventional method.

  Organic fiber cords other than steel cords include polyethylene naphthalate (PEN), polyethylene terephthalate (PET), rayon, Zylon (registered trademark) (polyparaphenylene benzobisoxazole (PBO) fiber), aliphatic Examples thereof include a cord made of polyamide (nylon) or the like. Examples of inorganic fiber cords include cords made of carbon fiber, glass fiber, basalt fiber, and the like. Basalt fiber is a biomass material, has a small environmental load, and has low heat shrinkage characteristics. Therefore, cord shrinkage during vulcanization is low. Therefore, it is possible to suppress the deterioration of the new circularity of the tire due to the variation in the contraction of the cord. Therefore, the tire uniformity is improved and the rolling resistance is improved.

  In the insert reinforcing layer 8 according to the tire of the present invention, the ratio of cords other than steel cords in the reinforcing material is preferably 10 to 90%. By setting the ratio of the cords other than steel cords within the above range, it is possible to balance the in-plane bending rigidity and the out-of-plane bending rigidity of the insert reinforcing layer 8 and achieve both good driving stability and riding comfort. Can be made. In particular, it is preferable to adjust the ratio of the steel cord and the cord other than the steel cord so that the in-plane bending stiffness of the insert reinforcing layer 8 is 14 to 34 times the out-of-plane bending stiffness of the insert reinforcing layer. The number of reinforcements to be inserted in the insert reinforcing layer 8 is 20 pieces / 50 mm or more, preferably 30 to 50 pieces / 50 mm.

  In the tire 10 of the present invention, the insert reinforcing layer 8 is preferably formed by arranging reinforcing materials at 0 ° to 70 ° with respect to the radial direction. In the illustrated example, the insert reinforcing layer 8 is disposed in a region extending from the bead portion 1 to the sidewall portion 2, but at least in a region from the bead portion 1 through the sidewall portion 2 to the shoulder portion of the tread portion 3. It suffices that at least one layer is arranged in part, and two or more layers may be arranged. Also, the arrangement position in the tire width direction is not limited to the outer side in the tire width direction of the folded portion 4b of the carcass 4 shown in the figure, and between the bead filler 6 and the folded portion 4b of the carcass 4 (not shown), the carcass You may arrange | position between the main-body part 4a and the bead filler 6 (not shown).

  In the steel cord of the insert reinforcing layer 8 according to the tire of the present invention, the diameter of the steel filament is preferably 0.16 to 0.40 mm. If the steel filament diameter exceeds the above range, the tire weight increases, such being undesirable. On the other hand, if the filament diameter is less than the above range, sufficient strength may not be obtained.

  In the tire of the present invention, the belt layers 7a and 7b are formed by rubberizing steel cords arranged in parallel, and the cord angles can be appropriately set. The steel cord structure of the belt 7 is not particularly limited, and may be a single twist structure, a layer twist structure, or a bundle cord in which a plurality of steel filaments are bundled without being twisted together. Good. Further, the number of steel cords driven into the belt 7 is preferably 28 to 57 pieces / 50 mm. Furthermore, a cap layer 9a and a layer layer 9b are disposed as the belt reinforcing layer 9 on the outer side in the tire radial direction of the belt layers 7a and 7b. As shown in the drawing, the cap layer 9a is arranged in at least one layer over the entire width of the belt 7, and is formed by rubberizing organic fiber cords or inorganic fiber cords arranged substantially parallel to the tire circumferential direction. Further, the layer layer 9b is arranged in at least one layer in both end regions of the belt 7, and an organic fiber cord arranged substantially parallel to the tire circumferential direction is rubberized.

  In the pneumatic tire 10 of the present invention, it is important that the insert reinforcing layer 8 satisfies the above relationship, and there is no particular limitation on the configuration other than this. In the illustrated example, the tread portion 3, the sidewall portion 2, and the bead portion 1 have a toroidal shape extending from one bead portion 1 to the other bead portion 1, and the carcass 4 is composed of a single carcass ply. In this tire, a plurality of tires may be used, and as the cord of the carcass 4, an organic fiber cord extending in a direction substantially orthogonal to the tire circumferential direction, for example, an angle of 70 to 90 ° can be suitably used. Further, the tread portion 3 is reinforced by a belt 7 including at least two layers disposed in the tire radial direction outside the crown region of the carcass 4, in the illustrated example, two layers of a first belt layer 7 a and a second belt layer 7 b. However, the tire 10 of the present invention may have two or more layers.

  Further, a tread pattern is appropriately formed on the surface of the tread portion 3, and an inner liner may be formed on the innermost layer of the tread portion 3 (not shown). Furthermore, as a gas filled in the tire, an inert gas such as nitrogen, argon, helium, etc. can be used in addition to normal or air with adjusted oxygen partial pressure. The tire 10 of the present invention can be suitably used for passenger car tires.

Hereinafter, the present invention will be described in more detail with reference to examples.
<Examples 1-8, Reference Examples 1 and 2 and Comparative Examples 1 and 2>
As shown in FIG. 1, pneumatic tires in which one insert reinforcing layer was disposed from the bead portion to the sidewall portion were manufactured at a tire size of 225 / 45R17. A steel cord satisfying the conditions shown in Tables 1 to 3 below was used for the insert reinforcing layer, and the cord angle was 45 ° with respect to the radial direction. Steel cords were used for the two belt layers, the cord angles were ± 63 ° with respect to the circumferential direction, and nylon was used as the material for the cap layer and the layer layer.

<Steering stability and ride quality evaluation>
Each test tire was mounted on an actual vehicle, and the driver's feeling was evaluated by running the vehicle on the circuit. In addition, evaluation is (double-circle), (circle), (triangle | delta), and x in order with favorable.

<Rolling resistance>
In accordance with SAE J 1269, the low rolling resistance was measured using a rolling resistance tester. On the basis of Comparative Example 1, the case where it was superior was evaluated as ◎, and the case where it was equivalent was evaluated as ○. The obtained results are also shown in Tables 1-3.

  From Tables 1 to 3, it can be seen that the tire of the present invention is highly compatible with ride comfort and steering stability.

DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread part 4 Carcass 5 Bead core 6 Bead filler 7 Belt 8 Insert reinforcement layer 9 Belt reinforcement layer 9a Cap layer 9b Layer layer 10 Pneumatic tire (tire)

Claims (4)

A pair of left and right bead portions, a sidewall portion continuous to the outside in the radial direction of the bead portion, a tread portion straddling between the sidewall portions, and at least one sheet extending in a toroidal shape between the pair of left and right bead portions In a pneumatic tire having a carcass made of a carcass ply and at least one insert reinforcing layer disposed in at least a part of a region from the bead portion to the shoulder portion of the tread portion,
Reinforcement of the insert reinforcing layer, Ri Do from the steel cord and the code other than steel cord,
A pneumatic tire characterized in that a ratio of cords other than steel cords in the reinforcing material is 10 to 48% .   The pneumatic tire according to claim 1, wherein the steel cord is a steel monofilament.   The pneumatic tire according to claim 1 or 2, wherein the in-plane bending rigidity of the insert reinforcing layer is 14 to 34 times the out-of-plane bending rigidity of the insert reinforcing layer. The pneumatic tire according to any one of claims 1 to 3, wherein the reinforcing members of the insert reinforcing layer are arranged at 0 ° to 70 ° with respect to a radial direction.

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