JP6523761B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire (hereinafter, also simply referred to as a "tire"), and more specifically, a pneumatic tire which is highly compatible in lightness and cut resistance and is excellent in workability and cost in manufacturing. About.

  In recent years, in order to improve the fuel consumption of automobiles, demands for weight reduction of tires are increasing more and more. Conventionally, in order to reduce the weight of a tire, a technology is known in which a steel monofilament is used as a belt cord without being twisted instead of a twisted cord in which a plurality of steel filaments are twisted together as a belt cord. Cross belts have been developed in which at least two belt layers are arranged to cross each other. When the belt cord is monofilamentized as described above, the thickness of the belt layer can be reduced, so that the weight of the tire can be reduced.

  However, in the case of using a belt layer made of steel monofilaments, there is a problem that the bending rigidity (in-plane bending rigidity) in the belt surface is reduced. 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 for the fatigue resistance to bending which is reduced by monofilamentization.

Unexamined-Japanese-Patent No. 2012-254668

  However, the provision of the belt reinforcing layer made of steel cord increases the amount of steel used, which leads to an increase in the weight of the tire. Therefore, in the tire described in Patent Document 1, it is not possible to fully utilize the advantage of the weight reduction of the tire by forming the cross belt with the belt layer made of steel monofilaments, and the weight reduction of the tire is necessarily satisfactory. It is not the current situation. In the case of a belt layer made of steel monofilaments, if the belt angle is 35 ° or more with respect to the circumferential direction in order to impart in-plane bending stiffness, the stiffness in the tire circumferential direction is reduced, so cut resistance is improved. It may decrease. In addition, improvement in workability and manufacturing cost at the time of manufacturing a tire is also desired.

  Therefore, an object of the present invention is to provide a pneumatic tire that is highly compatible in lightness and cut resistance and is excellent in workability at the time of manufacturing and manufacturing cost.

  As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by setting the arrangement and the material of the belt layer and the belt auxiliary layer to predetermined ones. It came to complete.

That is, in the pneumatic tire according to the present invention, at least two layers of belt layers, in which a plurality of aligned steel monofilaments are embedded in rubber without being twisted, are arranged so as to cross each other between layers. In a pneumatic tire provided with a cross belt,
Between the layers of said cross belts there is provided at least one belt reinforcement layer in which a reinforcement element is embedded in rubber,
The angle of the cross belt with the steel monofilament of the cross belt is 35 ° or more, and the reinforcing element of the belt reinforcing layer is made of an organic fiber cord,
When the thickness of the belt layer 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 (1),
1.24 <(T + S) / (t + s) <3.63 (1)
It is characterized by satisfying the relationship represented by

  In the tire of the present invention, the organic fiber cord is preferably a cord made of at least one selected from the group consisting of polyethylene naphthalate, polyethylene terephthalate, nylon, polyketone, and rayon.

  According to the present invention, it is possible to provide a pneumatic tire capable of achieving both lightness and cut resistance in a highly compatible manner, and being excellent in workability at the time of production and cost.

FIG. 1 is a widthwise cross-sectional view of a pneumatic tire according to a preferred embodiment of the present invention. It is a schematic plan view which shows the relationship of the belt layer and belt reinforcement layer of the pneumatic tire concerning one preferable embodiment of this invention. FIG. 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 using 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. The tire 10 of the present invention includes a tread portion 1 forming a ground contact portion, a pair of sidewall portions 2 continuously extending inward in the tire radial direction on both sides of the tread portion 1, and each side as illustrated. And a bead portion 3 continuous to 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 made of a carcass ply which extends 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 provided outside 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 aligned in parallel in the tire width direction without being twisted in the rubber, and the first belt layer 5a and the The two belt layers 5 b are disposed to cross each other between the layers to form a cross belt 5.

  In the tire 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 arranging the steel monofilaments 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 the wear resistance of the tire 10 are secured. Preferably, the angle of the steel monofilament with respect to the tire circumferential direction is 45 ° or more.

  Furthermore, in the tire 10 of the present invention, at least one belt reinforcing layer 6 in which a reinforcing element is embedded in rubber is embedded between layers of the cross belt 5. FIG. 2 is a schematic plan view showing the relationship between the belt layer and the belt reinforcing layer of the pneumatic tire according to one preferred embodiment of the present invention. The belt layer (the first belt layer 5a and the second belt layer 5b in the illustrated example) of the tire according to the present invention has an angle of 35 ° or more with respect to the tire circumferential direction, so the tensile rigidity in the tire circumferential direction is It is not enough. Therefore, by arranging the belt reinforcing layer 6 between the layers of the cross belt 5, the insufficient tensile rigidity in the tire circumferential direction is compensated. Further, by inserting the belt reinforcing layer 6 between the layers of the cross belt 5, the cross belt layer (in the illustrated example, the second belt layer 5b) made of a steel monofilament plays a role of a protective layer to improve the cut resistance. be able to. The angle of the organic fiber cord of the belt reinforcing layer 6 is preferably 0 ° to 10 ° with respect to the circumferential direction of the tire because the purpose is to compensate for the tensile rigidity in the circumferential direction of the tire.

  Furthermore, in the tire 10 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 of using steel. In the tire 10 of the present invention, the reinforcing element constituting the belt reinforcing layer 6 is intended to secure tensile rigidity in the circumferential direction of the tire, so it is preferable to use a cord made of high-elasticity organic fiber. As the organic fiber cord, aromatic polyamide (aramid), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), rayon, Zylon (registered trademark) (polyparaphenylene benzobisoxazole (PBO) fiber), aliphatic polyamide ( Organic fiber cords such as nylon) can be used.

FIG. 3 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. In the tire 10 of the present invention, the thickness of the belt layer (the first belt layer 5a and the second belt layer 5b in the illustrated example) is S (mm), the diameter of the steel monofilament 7 is s (mm), the belt reinforcing layer 6 When the thickness of the organic fiber cord 8 is T (mm) and the diameter of the organic fiber cord 8 is t (mm) (see FIG. 2), the following formula (1),
1.24 <(T + S) / (t + s) <3.63 (1)
It is preferable to satisfy the relationship represented by 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 at least 1.25, belt edge separation (BES) in which the interlayer gauge is maintained and rubber peeling starting from the cord end at the belt width direction end easily propagates between adjacent cords (BES Can be well prevented. On the other hand, by setting the amount to less than 3.63, the amount of rubber used can be reduced, and belt edge separation resistance (hereinafter referred to as "BES resistance") and lightness can be compatible.

  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 refers to the maximum width of the tire contact surface in the tire axial direction when the tire is mounted on a regular rim, filled with a regular internal pressure, placed perpendicular to a 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 the organic fiber cords 8 in the belt reinforcing layer 6 is preferably 20 to 80/50 mm. The tensile rigidity in the circumferential direction of the tire can be sufficiently secured by setting the number to be driven to 20/50 mm or more. On the other hand, the tensile rigidity of the tire circumferential direction and the BES resistance can be made compatible by setting the number of insertions to 80/50 mm or less.

  Moreover, in the tire 10 of the present invention, the total fineness of the organic fiber cords 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 secured. On the other hand, the total fineness of the organic fiber cord 8 is preferably 8000 dtex or less, and by setting the total fineness to 8000 dtex or less, thinning of the belt reinforcing layer 6 can be achieved to achieve both tensile rigidity in the circumferential direction and weight reduction.

  Furthermore, in the tire 10 of the present invention, the wire diameter of the steel monofilaments 7 constituting the cross belt 5 is preferably 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 0.25-0.35 mm.

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

  Furthermore, in the tire 10 of the present invention, it is preferable that the intervals between the steel monofilaments 7 be equal. By making the intervals between the steel filaments 7 uniform, the manufacture of the belt treat becomes easy and the productivity is improved. In addition, 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 at symmetrical angles with respect to the tire circumferential direction. With this configuration, the productivity of the tire can be improved, and stress can be shared equally, which is preferable from the viewpoint of tire durability.

  In the tire 10 of the present invention, at least the belt layers formed by embedding a plurality of steel monofilaments aligned without being twisted together in the tire radial direction outer side of the carcass 4 in the rubber cross each other between the layers. The cross section of the steel monofilament of the cross belt 5 is provided with at least one belt reinforcing layer 6 in which a reinforcing element is embedded in rubber between the layers of the cross belt 5. It is only important to set the angle to the direction to 35 ° or more and to use the organic fiber cord as a reinforcing element, and for other structures, known structures can be adopted.

  For example, as shown in the drawings, bead cores 9 are embedded in a pair of bead portions 3 of the tire according to the present invention, and the carcass 4 is folded around the bead cores 9 from the inside to the outside of the tire and locked. The carcass usually comprises a carcass ply of at least one layer (one layer in the illustrated example) composed of a plurality of organic fiber cords arranged at a cord angle of 70 ° to 90 ° with respect to the tire equatorial plane. The organic fiber cord used for the carcass can be a single-twist cord, a twin-twist cord, or three or more multi-twist cords. The organic fiber cord used for the carcass may be a strand of filaments of one type of organic fiber or a strand of filaments of two or more types of organic fibers. Furthermore, it is preferable that the number of impacts of the organic fiber cord used for the carcass is 40 to 70 per 50 mm.

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

Hereinafter, the present invention will be described in more detail using examples.
Examples 1-5
A tire of the type shown in FIG. 1 was produced at a tire size of 145 / 65R15. A cross belt is composed of the first layer (first belt layer) and the third layer (second belt layer), and the second layer is a belt reinforcing layer. The wire diameter of the steel filament that constitutes the first and third layers is 0.3 mm, the number of threadings is 45/50 mm, the angle to the circumferential direction of the tire is + 45 ° for the first belt layer, -45 for the second belt layer °. The second layer is a belt reinforcing layer, and the reinforcing elements are disposed substantially in parallel to the tire circumferential direction over the entire width in the tread width direction. The reinforcing elements and the structure of the second layer (belt reinforcing layer) are as shown in Tables 1 and 2. The number of reinforcement elements of the second layer (belt reinforcing layer) was 50/50 mm.

<Conventional example>
Tire size: A pneumatic tire having a cross belt consisting of a first layer and a second layer was produced at 145 / 65R15. The reinforcing element of the cross belt is a steel cord of a 1 × 3 structure made of steel filament having a wire diameter of 0.30 mm, the number of implantation is 45/50 mm, and the angle to the circumferential direction of the tire is ± 45 °. The conventional tire does not have a belt reinforcing layer.

Comparative Example 1
The tire of Comparative Example 1 has a tire size of 145 / 65R15, and a steel filament constituting a cross belt by the first layer (first belt layer) and the second layer (second belt layer) and constituting these belt layers The wire diameter was 0.3 mm, the number of punches was 45/50 mm, the angle with respect to the circumferential direction of the tire was + 45 ° for the first belt layer and −45 ° for the second belt layer. The third layer is a belt reinforcing layer, and is disposed such that the reinforcing elements are substantially parallel to the tire circumferential direction over the entire width in the tread width direction. The reinforcing elements and the structure of the third layer (belt reinforcing layer) are as shown in Table 2, and the number of impact was 50/50 mm.

Comparative Example 2
The tire of Comparative Example 2 has a tire size of 145 / 65R15, and a steel filament constituting a cross belt by the first layer (first belt layer) and the second layer (second belt layer) and constituting these belt layers The wire diameter was 0.3 mm, the number of punches was 45/50 mm, the angle with respect to the circumferential direction of the tire was + 45 ° for the first belt layer and −45 ° for the second belt layer. The third layer and the fourth layer are belt reinforcing layers, and were arranged such that the reinforcing elements were substantially parallel to the tire circumferential direction over the entire width in the tread width direction. The reinforcing elements and the structures of the third and fourth layers (belt reinforcing layer) are as shown in Table 2, and the number of inserted sheets was 50/50 mm.

  Evaluation of the tire weight was performed for each of the obtained tires according to the following procedure.

<Tire weight>
The weight per tire was measured, and the case equivalent to the tire of the conventional example was evaluated as Δ, the case where the weight was reduced by less than 50 g compared to the conventional example was evaluated as ○, and the case where the weight was reduced 50 g or more as ◎. The results are shown in Tables 1 and 2.

<Cut resistance>
The tire was assembled to a rim specified by JATMA, a load twice as much as the normal load, and an indoor drum test in which protrusions were provided on the surface of the drum, and evaluation was made based on the distance to tire breakage. When the tire of the conventional example is used as a standard (index: 100), the case of less than 100 is Δ, the case of 100 to 110 is ○, and the case of more than 110 is 。. The results are shown in Tables 1 and 2.

<Skilled workability>
Based on the replacement frequency of the cutting edge in the manufacture of the conventional example as a standard (index: 100), the case of less than 100 was Δ, the case of 100 to 120 was ○, and the case of over 120 was ◎. The results are shown in Tables 1 and 2.

<Cost>
The cost of the tire of the conventional example was taken as a standard (index: 100), and the case of 101 or more was Δ, the case of 100 was 100, and the case of less than 100 was を. The results are shown in Tables 1 and 2.

  From the above Tables 1 and 2, it can be seen that the tire of the present invention is highly compatible in lightness and cut resistance. In addition, it is also understood that the use of cords made of PEN, PET, nylon, polyketone, and rayon as the organic fiber cords of the belt reinforcing layer is also excellent in terms of workability and cost.

Reference Signs List 1 tread portion 2 sidewall portion 3 bead portion 4 carcass 5 cross belt 5a first belt layer 5b second belt layer 6 belt reinforcing layer 10 pneumatic tire (tire)

Claims (2)

In a pneumatic tire comprising a cross belt in which a belt layer in which a plurality of steel monofilaments drawn and aligned without being twisted is embedded in rubber is disposed so that at least two layers cross each other between layers,
Between the layers of said cross belts there is provided at least one belt reinforcement layer in which a reinforcement element is embedded in rubber,
The crossing angle with respect to the tire circumferential direction of the steel monofilaments of the belt is at 35 ° or more, and, Ri reinforcing element organic fiber cord Tona of the belt reinforcing layer,
When the thickness of the belt layer 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 (1),
1.24 <(T + S) / (t + s) <3.63 (1)
In a pneumatic tire characterized that you satisfy the relationship represented.   The pneumatic tire according to claim 1, wherein the organic fiber cord is at least one cord selected from the group consisting of polyethylene naphthalate, polyethylene terephthalate, nylon, polyketone, and rayon.

Images