JP6480794B2 - 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 with improved lightness and road noise.

  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-plane bending rigidity) in the belt surface 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. In addition to the environmental performance of tires, improvement in ride comfort such as reduction in road noise is also demanded.

  Therefore, an object of the present invention is to provide a pneumatic tire with improved lightness and road noise.

  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 element of the carcass or the belt reinforcing layer to a predetermined one, and the present invention has been completed. It came to do.

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,
As a reinforcing element of at least one of the carcass and the belt reinforcing layer, a cord containing porous fibers is used,
The porous fiber is a porous inorganic fiber.

In addition, another pneumatic tire of the present invention has 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. In a pneumatic tire provided with a cross belt formed by arranging at least two layers,
As the carcass reinforcing element, a cord containing porous fibers is used,
The porous fiber is a porous inorganic fiber.

In the tire of the present invention, the porous fiber is preferably a basalt fiber or a glass fiber. Moreover, in the tire of this invention, it is preferable that the angle with respect to the tire circumferential direction of the reinforcement element of the said belt reinforcement layer is 0-10 degrees. Furthermore, in the tire of the present invention, it is preferable that the number of steel monofilaments for the cross belt is 26 to 100/50 mm. Furthermore, in the tire according to the present invention, it is preferable that the angle of the steel monofilament of the cross belt with respect to the tire circumferential direction is 35 ° or more. In the tire of the present invention, 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 porous fiber is When the diameter of the cord to be included is t (mm), the following formula (1),
1.24 <(T + S) / (t + s) <3.63 (1)
It is preferable to satisfy the relationship represented by these. Furthermore, in the tire of the present invention, when the interlayer rubber gauge of the at least two belt layers is h1, and the interlayer rubber gauge of the belt layer and the belt reinforcing layer is h2, the following formula (2):
h1> h2 (2)
It is preferable to satisfy the relationship represented by these.

  According to the present invention, it is possible to provide a pneumatic tire with improved lightness and road noise.

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 width direction sectional view of the pneumatic tire concerning other suitable embodiments 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 widthwise sectional view of a pneumatic tire according to one preferred embodiment of the present invention, and FIG. 2 is a widthwise sectional view of a pneumatic tire according to another preferred embodiment of the present invention. It is. As shown in the figure, the tires 10 and 20 of the present invention include tread portions 1 and 11 forming a ground contact portion, and a pair of sidewalls extending inward in the tire radial direction continuously to both side portions of the tread portions 1 and 11. Parts 2, 12 and bead parts 3, 13 continuous on the inner peripheral side of each side wall part 2, 12. The tread portions 1, 11, the sidewall portions 2, 12 and the bead portions 3, 13 are a carcass 4 made of a single carcass ply extending in a toroid shape from one bead portion 3, 13 to the other bead portion 3, 13, 14 is reinforced.

  In the tires 10 and 20 of the present invention, at least two layers (two layers in the illustrated example), preferably two layers of the first belt layers 5a and 15a, and the second layers are disposed on the outer side in the tire radial direction of the crown regions of the carcass 4 and 14. A belt composed of belt layers 5b and 15b is disposed. The first belt layers 5a and 15a and the second belt layers 5b and 15b are formed by embedding a plurality of steel monofilaments arranged in parallel in the tire width direction without being twisted in the rubber. The layers 5a and 15a and the second belt layers 5b and 15b are arranged so as to intersect each other between the layers to form the intersecting belts 5 and 15. In the tire 10 according to the preferred embodiment of the present invention shown in FIG. 1, at least one of the cross belt 5 in the tire radial direction outer side, the tire radial direction inner side, and the cross belt layers (in the illustrated example, the cross belt). 5), at least one belt reinforcing layer 6 in which a reinforcing element is embedded in rubber is embedded.

  In the tire according to one preferred embodiment of the present invention shown in FIG. 1, a cord including porous fibers (hereinafter referred to as “porous”) is used as at least one of the reinforcing element of the carcass 4 and the belt reinforcing layer 6. Also called “fiber cord”. Further, in the tire according to another preferred embodiment of the present invention shown in FIG. 2, there is no belt reinforcing layer, and the reinforcing element of the carcass 14 includes a cord including porous fibers. Since the porous fibers are excellent in sound absorption, the tires 10 and 20 of the present invention can reduce road noise. Here, the cord including the porous fiber may be a cord composed of only the porous fiber, or may be a cord composed of the porous fiber and other fibers. Further, all of the reinforcing elements may be cords including porous fibers, and some may be cords including porous fibers. In the tires 10 and 20 of the present invention, as the porous fibers, porous organic fibers and porous inorganic fibers can be raised, but cords containing porous inorganic fibers are preferable, and in particular, only porous inorganic fibers are included. A code is preferred.

  Examples of the inorganic porous fiber include carbon fiber, glass fiber, and basalt fiber. Among these, basalt fiber is preferable in the tire 10 of the present invention. 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. Polyester fibers and polyamide fibers, which are organic fibers, are not preferable because they use fossil fuel as a raw material and have a high environmental load. In particular, aramid fibers are not preferable because sulfuric acid is used in the production process, and the environmental load is high.

  In the tires 10 and 20 of the present invention, as described above, the cord including the porous fiber may be a cord made of only the porous fiber, but is a cord made of the porous fiber and other fibers. May be. Examples of other fibers include organic fibers such as polyethylene naphthalate (PEN), polyethylene terephthalate (PET), rayon, Zylon (registered trademark) (polyparaphenylene benzobisoxazole (PBO) fiber), and aliphatic polyamide (nylon). Can be used.

  In the tire 10 according to a preferred embodiment of the present invention, the angle of the reinforcing element of the belt reinforcing layer 6 is to compensate for the tensile rigidity in the tire circumferential direction that lacks its purpose. It is preferably 0 ° to 10 °. FIG. 3 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. 3 (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.

  In the tires 10 and 20 of the present invention, the number of steel filaments driven into the cross belt 5 is preferably 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.

  Furthermore, in the tires 10 and 20 of the present invention, the angle of the steel monofilament of the cross belt 5 with respect to the tire circumferential direction is preferably 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. If the angle of the steel monofilament of the cross belt 5 with respect to the tire circumferential direction is 35 ° or more, the in-plane rigidity in the tire ground contact width direction is improved, so that the vibration of air in the tire lumen is deteriorated. However, in the tire 10 of the present invention, since the porous fiber cord is used as the reinforcing element of the carcass 4 and the reinforcing element of the belt reinforcing layer 6, such a problem with road noise does not occur.

  In the tire 10 according to a preferred embodiment of the present invention, the belt reinforcing layer 6 is inserted between the layers of the cross belt 5 or the belt reinforcing layer 6 is disposed on the inner side in the tire radial direction of the cross belt 5. In this case, the cross belt layer (second belt layer 5b in the illustrated example) made of steel monofilament serves as a protective layer, and cut resistance is improved.

FIG. 4 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. In the tire 10 according to one preferred embodiment of the present invention, the thickness of the belt layers (the first belt layer 5a and the second belt layer 5b in the illustrated example) is S (mm), and the diameter of the steel monofilament 7 is s. (Mm), when the thickness of the belt reinforcing layer 6 is T (mm) and the diameter of the porous fiber cord 8 is t (mm) (see FIG. 4), the following formula (1),
1.24 <(T + S) / (t + s) <3.63 (1)
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, by using less than 3.63, the amount of rubber used can be reduced, and both BES resistance and light weight can be achieved.

In the tires 10 and 20 of the present invention, the interlayer rubber gauge of at least two belt layers (in the illustrated example, the rubber gauge of the first belt layer 5a and the second belt layer 5b) is h1, and the interlayer rubber gauge of the belt layer and the belt reinforcing layer. When the rubber gauge of the second belt layer 5b and the belt reinforcing layer 6 in the illustrated example is h2, the following formula (2),
h1> h2 (2)
It is preferable to satisfy the relationship represented by these.

  In the tires 10 and 20 of the present invention, when the cross belt 5 is at a high angle with respect to the tire circumferential direction, the in-plane bending rigidity is increased. 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 according to a preferred embodiment of the present invention, the belt reinforcing layer 6 is not limited to one layer, and a plurality of layers may be provided. In this case, it is preferable that at least one of the belt reinforcing layers 6 has a width that is 10% or more of the maximum belt width of the cross belt 5 from the center of the tire toward both width directions. Thereby, road noise can be reduced favorably. Preferably, it is 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.

  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 have 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 tires 10 and 20 of the present invention, it is preferable that the number of cords including porous fibers that are the reinforcing elements of the carcass 4 and the reinforcing elements of the belt reinforcing layer 6 is 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.

  Moreover, in the tires 10 and 20 of the present invention, the total fineness of the cords including porous fibers that are the reinforcing elements of the carcass 4 and the reinforcing elements of the belt reinforcing layer 6 is preferably 470 to 5000 dtex. By setting the total fineness of the porous fiber cord 8 to 470 dtex or more, the circumferential tensile rigidity of the belt reinforcing layer 6 can be sufficiently secured. On the other hand, the belt reinforcing layer 6 can be thinned with the porous fiber cord, and both the circumferential tensile rigidity and the weight reduction can be achieved. In the tire according to the present invention, the cord including the porous fiber which is the reinforcing element of the carcass 4 and the reinforcing element of the belt reinforcing layer 6 may be a twisted cord in which three or more are twisted or twisted together. Good. In this case, the upper twist coefficient is desirably 0.05 to 0.8.

  Furthermore, in the tires 10 and 20 of the present invention, the wire diameter of the steel monofilament 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 to 0.35 mm.

  Furthermore, it is preferable that the steel monofilament 7 constituting the cross belt 5 and the porous 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 tires 10 and 20 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 tires 10 and 20 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.

  It is important that the tires 10 and 20 of the present invention only satisfy the above-described configuration, and known structures 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 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.

  The carcass 4 is usually composed of at least one layer (in the illustrated example, one layer) of carcass plies composed of a plurality of reinforcing elements arranged at a cord angle of 70 ° to 90 ° with respect to the tire equatorial plane. It is not restricted to this, You may consist of two or more layers of carcass plies. When a cord containing porous fibers is not used as the reinforcing element of the carcass 4, an organic fiber cord can be used. The organic fiber cord may be a single twist cord, a double twist cord, or a multi-twist cord of three or more.

  Furthermore, in the tires 10 and 20 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. Furthermore, in the tires 10 and 20 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 13, Comparative Examples 1 and 2 and Conventional Examples 1 and 2>
Examples 1-12, Comparative Examples 1 and 2, and Conventional Examples 1 and 2 are tires of the type shown in FIG. 1, and Example 13 is a tire of the type shown in FIG. 2 at a tire size of 195 / 65R15. Produced. The wire diameter of the steel filament constituting the cross belt, the number of driven wires, and the angle with respect to the tire circumferential direction are as shown in Tables 1 to 4 below. The belt reinforcement layer was substantially parallel to the tire circumferential direction, and the number of driven-in layers was 45/50 mm. Further, the carcass was substantially perpendicular to the tire circumferential direction, and the number of drivings was 50/50 mm. Each tire obtained was evaluated for lightness, road noise, and rolling resistance according to the following procedure.

<Lightweight>
The weight per tire was measured, and the case where it was equivalent to the tire of Conventional Example 1 was evaluated as Δ, the case where the weight could be reduced by less than 100 g compared to the conventional example, and the case where the weight could be reduced by 100 g or more. The results are also shown in Tables 1-4.

<Road noise>
The obtained tires were mounted on a 1800cc passenger car with all four wheels, two people boarded, traveled on the road noise evaluation road test course at a speed of 60 km / h, and attached to the center of the backrest of the driver's seat The total sound pressure (decibel) of frequencies 100 to 500 Hz and 300 to 500 Hz was measured with a sound collecting microphone, and road noise was evaluated from the measured values. The result shows that the road noise becomes smaller as the exponent value becomes larger, assuming that the road noise of the conventional example is 100. The results are also shown in Tables 1-4.

<Rolling resistance>
The obtained tire was assembled on a regular rim specified by JATMA, filled with 210 kPa of internal pressure, pressed against the surface of the drum having a diameter of 1.7 m with a load of 4 kN, and conditioned for 30 minutes at a speed of 80 km / h. After that, coasting was performed from 240 km / h to 18 km / h, and the rolling resistance value was calculated from the required time. The numerical values in the table below are index indications when the rolling resistance value of the tire of the conventional example is set to 100, and the larger the index value, the smaller the rolling resistance. The results are also shown in Tables 1-4.

※：スチールモノフィラメント

*: Steel monofilament

  From the said Tables 1-4, it turns out that the tire of this invention has improved the lightness and road noise. Moreover, it turns out that rolling resistance is also improved.

DESCRIPTION OF SYMBOLS 1,11 Tread part 2,12 Side wall part 3,13 Bead part 4,14 Carcass 5,15 Cross belt 5a, 15a 1st belt layer 5b, 15b 2nd belt layer 6 Belt reinforcement layer 7 Steel filament 8 Porous fiber Code 9,19 Bead core 10,20 Pneumatic tire (tire)

Claims (10)

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,
As a reinforcing element of at least one of the carcass and the belt reinforcing layer, a cord containing porous fibers is used ,
The pneumatic tire is characterized in that the porous fiber is a porous inorganic fiber . The pneumatic tire of claim 1, wherein the angle with respect to the tire circumferential direction of the reinforcing elements of the belt reinforcing layer is 0 °. The pneumatic tire according to claim 1 or 2, wherein the end count of the steel monofilaments is 26 to 100 present / 50 mm of the crossing belt. The pneumatic tire according to any one of claims 1 to 3 , wherein an angle of a steel monofilament of the cross belt with respect to a tire circumferential direction is 35 ° or more. 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 cord including the porous fiber is t (mm). When the following formula (1),
1.24 <(T + S) / (t + s) <3.63 (1)
The pneumatic tire according to any one of claims 1 to 4 , which satisfies a relationship represented by: 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 (2):
h1> h2 (2)
The pneumatic tire according to any one of claims 1 to 5, which satisfies a relationship represented by: The pneumatic tire according to any one of claims 1 to 6 , wherein the porous inorganic fiber is a basalt fiber or a glass fiber. 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:
As the carcass reinforcing element, a cord containing porous fibers is used ,
The pneumatic tire is characterized in that the porous fiber is a porous inorganic fiber . The pneumatic tire according to claim 8, wherein an angle of the steel monofilament of the cross belt with respect to a tire circumferential direction is 35 ° or more. The pneumatic tire according to claim 8 or 9 , wherein the porous inorganic fiber is a basalt fiber or a glass fiber.

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