JP6699108B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire provided with a carcass layer, and more specifically, it is possible to increase in-plane bending rigidity while maintaining good flexibility against out-of-plane deformation of a reinforcing member used for the carcass layer. , And thereby to a pneumatic tire which makes it possible to increase the tire circumferential stiffness without depending on an additional bead reinforcing layer.

  In a pneumatic tire, a carcass layer is mounted between a pair of bead portions. Such a carcass layer includes a plurality of reinforcing cords arranged in the tire radial direction. However, since the reinforcing cords are substantially independent of each other, the contribution to the tire circumferential rigidity is small. Therefore, for example, when increasing tire circumferential rigidity for the purpose of improving steering stability, a bead reinforcing layer is generally added from the bead portion to the sidewall portion (for example, Patent Documents 1 to 3). reference).

  However, the addition of the bead reinforcement layer will result in a corresponding increase in tire weight. Therefore, it is not always best to rely on an additional bead reinforcement layer to increase tire circumferential stiffness.

JP, 2010-221920, A JP, 2013-35362, A JP, 2014-227149, A

  The object of the invention is to be able to increase the in-plane bending stiffness while maintaining good flexibility against out-of-plane deformation of the reinforcement members used in the carcass layer, thereby relying on an additional bead reinforcement layer. It is to provide a pneumatic tire capable of increasing the tire circumferential rigidity without any increase.

The pneumatic tire of the present invention for achieving the above-mentioned object, a tread portion which extends in the tire circumferential direction and forms an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and these sidewall portions. In a pneumatic tire having a pair of bead portions arranged on the inner side in the tire radial direction, wherein a carcass layer is mounted between the pair of bead portions, as the carcass layer, at least three directions in the region on the bead portion side. A reinforcing member having a net-like structure in which at least three reinforcing cords having different orientations are joined to each other at a crossing point of at least a part of these reinforcing cords , and the carcass layer is It is characterized in that it is formed by processing a reinforcing member having a net-like structure into an endless annular shape .

  In the present invention, the reinforcing member used for the carcass layer includes a plurality of reinforcing cords that are oriented in at least three directions in the region on the bead portion side, and the orientation direction is different at least at a portion where the reinforcing cords intersect. Since the three reinforcing cords have a net-like structure joined to each other, the in-plane bending rigidity can be increased while maintaining good flexibility against the out-of-plane deformation.

  Therefore, when the reinforcing member having the above-mentioned network structure is used as the carcass layer, the tire circumferential rigidity can be increased without depending on the additional bead reinforcing layer, and by extension, the tire weight is substantially increased. The steering stability can be improved without any.

  In the present invention, at least three reinforcing cords are preferably joined to each other at at least 30% of the intersecting points where at least three reinforcing cords intersect. Thereby, the effect of increasing the in-plane bending rigidity can be sufficiently obtained.

  Further, it is preferable that the intersecting angle of at least three reinforcing cords joined at the intersecting point is 15° or more. Thereby, the effect of increasing the in-plane bending rigidity can be sufficiently obtained.

  The carcass layer is preferably formed by processing a reinforcing member having a net-like structure into an endless ring. This improves the durability of the tire.

  The reinforcing cord preferably contains a chemical fiber cord having a knot strength of 1.5 (cN/dtex) or more. In the case of the chemical fiber cord, a reinforcing member having a network structure can be easily formed, and the chemical fiber cord having the above knot strength is suitable as a reinforcing material for the carcass layer.

  Further, it is preferable that the reinforcing member having the mesh structure is covered with rubber. Thereby, the integrity of the reinforcing cord can be secured and the in-plane bending rigidity of the reinforcing member can be increased.

It is a meridian sectional view showing a pneumatic tire which consists of an embodiment of the present invention. It is a top view which shows an example of the reinforcement member used for the carcass layer of the pneumatic tire of this invention. It is explanatory drawing which shows the deformation|transformation mechanism of the reinforcing member which has the net-like structure which joined together at least 3 reinforcing cords from which the orientation direction differs at the intersection of a reinforcing cord. It is explanatory drawing which shows the deformation|transformation mechanism of the reinforcement member which has the net-like structure which joined two reinforcement cords from which the orientation directions differ at the intersection of reinforcement cords mutually. It is a top view which shows the modification of the reinforcement member used for the carcass layer of the pneumatic tire of this invention. It is a meridian half cross section which shows the pneumatic tire which consists of other embodiment of this invention. It is a top view which shows an example of the reinforcement member used for the carcass layer of the pneumatic tire of FIG.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire according to an embodiment of the present invention. As shown in FIG. 1, the pneumatic tire of the present embodiment has a tread portion 1 extending in the tire circumferential direction and forming an annular shape, and a pair of sidewall portions 2 and 2 arranged on both sides of the tread portion 1. And a pair of bead portions 3 disposed inside the sidewall portion 2 in the tire radial direction.

  A carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 is composed of a reinforcing member 10 having a specific net-like structure, which will be described later, and is folded back from the inside of the tire to the outside of the bead core 5 arranged in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross section is arranged on the outer periphery of the bead core 5.

  On the other hand, a belt layer 7 is embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. The belt layer 7 includes a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to intersect each other between the layers. In the belt layer 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in the range of 10° to 40°, for example. A steel cord is preferably used as the reinforcing cord of the belt layer 7. On the outer peripheral side of the belt layer 7, for the purpose of improving high-speed durability, there is arranged at least one belt cover layer 8 in which reinforcing cords are arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction. There is. As the reinforcing cord of the belt cover layer 8, a chemical fiber cord such as nylon or aramid is preferably used. The belt cover layer 8 is not always necessary.

  FIG. 2 shows an example of a reinforcing member used for the carcass layer of the pneumatic tire of the present invention. As shown in FIG. 2, the reinforcing member 10 having a mesh structure includes a plurality of reinforcing cords 11 to 14 oriented in four directions. That is, the reinforcement cord 11 extends in parallel with the tire width direction W over the entire tire width direction W, the reinforcement cord 12 extends in parallel with the tire circumferential direction C only in the region adjacent to the bead core 5, and the reinforcement cord 13 Extends so as to incline to one side in the tire width direction W only in the region on the bead portion 3 side, and the reinforcing cord 14 inclines to the other side in the tire width direction W only in the region on the bead portion 3 side. Has been extended to do. The tire width direction W is the direction in the sheet-shaped reinforcing member 10, but is recognized as the tire radial direction in the state of being processed into a pneumatic tire. At the intersections of the reinforcing cords 11 to 14, at least three reinforcing cords 11 to 14 having different orientations are integrally joined to form a plurality of joints 15.

  The material of the reinforcing cords 11 to 14 is not particularly limited, and chemical fiber cords or steel cords can be used as the reinforcing cords 11 to 14. For example, a structure using chemical fiber cords for all of the reinforcing cords 11 to 14, a structure using chemical fiber cords for the reinforcing cords 11, 13, and 14 while using a steel cord for the reinforcing cords 12, steel for the reinforcing cords 11 Examples of the structure include a cord that uses a chemical fiber cord for the reinforcing cords 12 to 14, and a steel cord for the reinforcing cords 11 and 12 while using a chemical fiber cord for the reinforcing cords 13 and 14. it can.

  The method of joining the reinforcing cords 11 to 14 is not particularly limited, and various methods can be adopted. In the case of a chemical fiber cord, the joint portion 15 is formed so that the cords form a knot, or the joint portion 15 is formed so that both fiber bundles (yarns) intersect each other without forming a knot. Can be formed, the cord 15 can be welded together to form the joint 15, or the cords can be adhered together to form the joint 15. In the case of a steel cord, the joint 15 is formed so that both filaments intersect each other without forming a knot, or the joint 15 is formed by welding the cords together, or the cords are The bonding portion 15 can be formed by bonding. In any case, it is necessary that the cords be integrally connected at the intersection so as to regulate each other's position.

  The reinforcing member 10 configured as described above includes a plurality of reinforcing cords 11 to 14 oriented in at least three directions in the region on the bead portion 3 side, and at least at a portion where these reinforcing cords 11 to 14 intersect. Since it has a net-like structure in which at least three reinforcing cords 11 to 14 having different orientations are joined to each other, it is possible to increase the in-plane bending rigidity while maintaining good flexibility against the out-of-plane deformation.

  FIG. 3 shows a deformation mechanism of a reinforcing member having a mesh structure in which at least three reinforcing cords having different orientations are joined to each other at the intersection of the reinforcing cords, and FIG. 3 shows a deformation mechanism of a reinforcing member having a net-like structure in which the reinforcing cords are joined together. As shown in FIG. 4, at the intersection of the reinforcing cords 11 and 12, two reinforcing cords 11 and 12 having different orientations are joined to each other to form a joint portion 16. When a force is applied in the direction, it deforms like a pantograph. On the other hand, as shown in FIG. 3, at the intersection of the reinforcing cords 11 to 14, at least three reinforcing cords 11 to 14 having different orientations are joined to each other to form a joint portion 15. The member 10 has a planar truss structure, is hard to be deformed even when a force is applied in the surface direction, and has high in-plane bending rigidity.

  Therefore, in the pneumatic tire in which the carcass layer 4 is mounted between the pair of bead portions 3 and 3, when the reinforcing member 10 having the mesh structure is used as the carcass layer 4, it depends on the additional bead reinforcing layer. It is possible to increase the tire circumferential rigidity without increasing the tire circumferential rigidity, and it is possible to improve the steering stability without substantially increasing the tire weight. The reinforcing member 10 has a mesh structure in which at least three reinforcing cords 11 to 14 having different orientations are joined to each other in the region on the bead portion 3 side, but has a mesh structure in the region on the tread portion 1 side. Since it does not have it, it can expand in the tire molding process. From such a viewpoint, it is preferable that the reinforcing member 10 does not have the joining point 15 on the outer side in the tire radial direction with respect to the tire maximum width position.

  In the pneumatic tire, at least three reinforcing cords 11 to 14 are joined to each other at all intersections where at least three reinforcing cords 11 to 14 intersect, but at least three reinforcing cords 11 to 14 are joined. It is desirable to join at least three reinforcing cords 11 to 14 to each other at at least 30% of the intersecting points, more preferably at least 50% (most preferably 70% or more) of the intersecting points. .. Thereby, the effect of increasing the in-plane bending rigidity can be sufficiently obtained. If this ratio is too small, the effect of improving the in-plane bending rigidity decreases.

  In the pneumatic tire, the crossing angle of at least three reinforcing cords 11 to 14 joined at the crossing point is 15° or more, and more preferably 20° to 75°. Thereby, the effect of increasing the in-plane bending rigidity can be sufficiently obtained. If this intersection angle is too small, the effect of improving the in-plane bending rigidity will be reduced. In addition, in the embodiment of FIG. 2, the crossing angle of the reinforcing cords 11 to 14 is 45°.

  FIG. 5 shows a modification of the reinforcing member used for the carcass layer of the pneumatic tire of the present invention. FIG. 5 shows only one side of the tire center line CL extracted. In FIG. 5, at least three reinforcing cords 11 to 14 are integrally joined at a crossing point where at least three reinforcing cords 11 to 14 intersect to form a plurality of joints 15. At least at some intersections where the cords 13 and 14 intersect, the two reinforcing cords 13 and 14 are integrally joined to form a plurality of joints 16. Then, the regions of the reinforcing member 10 in which the joint portions 15 and 16 are formed are moved from the position of the bead core 5 toward the tire radial direction outer side (in the plan view of FIG. 5, from the position of the bead core 5 to both outer sides in the tire width direction), respectively. When divided into two areas A1 to A4, the densities of the joint portions 15 and 16 in these areas A1 to A4 are set to be higher toward the inner side in the tire radial direction. However, the densities of the joint portions 15 and 16 in the regions A1 and A2 are equivalent. With such an arrangement, the in-plane bending rigidity can be effectively increased without inhibiting the deformation of the reinforcing member 10 forming the carcass layer 4 in the tire forming process.

  FIG. 6 shows a pneumatic tire according to another embodiment of the present invention, and FIG. 7 shows a reinforcing member used for a carcass layer of the pneumatic tire. In FIG. 6, the carcass layer 4 is folded back from the tire inner side to the outer side around the bead core 5 arranged in each bead portion 3, and the folded end portion is arranged so as to be sandwiched between the belt layer 7 and the carcass layer 4. It has a winding structure.

  As shown in FIG. 7, the reinforcing member 10 used for the carcass layer 4 includes a plurality of reinforcing cords 11 to 14 oriented in at least three directions in the region on the bead portion 3 side. No. 14 to No. 14 have a net-like structure in which at least three reinforcing cords 11 to 14 having different orientations are joined to each other at an intersecting portion. That is, the reinforcing cord 11 extending in the tire width direction W extends over the entire area in the tire width direction W, but the mesh structure including the joint portion 15 is selectively formed only in the region corresponding to the bead portion 3. There is. Also in this case, it is possible to increase the in-plane bending rigidity while maintaining the flexibility of the reinforcing member 10 against the out-of-plane deformation.

  The carcass layer 4 described above can be formed by processing the reinforcing member 10 having a net-like structure into an endless annular shape. That is, the reinforcing member 10 can be formed by braiding in a ring shape. In this case, the durability of the pneumatic tire becomes good. Of course, the carcass layer 4 can also be formed by winding the reinforcing member 10 having a net-like structure one or more times along the tire circumferential direction. In this case, since the reinforcing member 10 having the net-like structure can be handled in the same manner as a conventional carcass member, the pneumatic tire can be easily manufactured.

  In the pneumatic tire, the reinforcing cords 11 to 14 have a tensile strength of 1.5 (cN/dtex) or more, a knot strength of 1.5 (cN/dtex) or more, and a hooking strength of 2.5( It is desirable to use a chemical fiber cord having a cN/dtex) or more. In the case of a chemical fiber cord, the reinforcing member 10 having a network structure can be easily formed, and the chemical fiber cord having the above physical properties is suitable as a reinforcing material for the carcass layer 4.

  Regarding the above physical properties, preferably, the tensile strength is 2.0 (cN/dtex) or more, the knot strength is 2.0 (cN/dtex) or more, and the hooking strength is 3.5 (cN/dtex) or more. More preferably, the tensile strength is 4.0 (cN/dtex) or more, the knot strength is 3.0 (cN/dtex) or more, and the hooking strength is 5.0 (cN/dtex) or more, and the most preferable. Has a tensile strength of 5.0 (cN/dtex) or more, a knot strength of 4.0 (cN/dtex) or more, and a hooking strength of 8.0 (cN/dtex) or more. The upper limit is not particularly limited, but the knot strength is 20 (cN/dtex) or less, the hooking strength is 20 (cN/dtex) or less, and the tensile strength is 15 (cN/dtex) or less. Is realistic. The knot strength and the hooking strength are measured according to JIS-L1013 (Chemical fiber filament yarn test method) and JIS-L1015 (Chemical fiber staple test method), respectively.

  Such chemical fiber cords include aramid fiber, polyketone fiber, polyethylene terephthalate (PET) fiber, polyethylene naphthalate (PEN) fiber, high molecular weight polyethylene fiber (Toyobo Dyneema, etc.), poly-paraphenylene benzobisoxazole (PBO). Those containing fibers are preferred. Of course, it is possible to change the material according to the cord extension direction. Further, a composite cord obtained by twisting fibers made of a low elongation material (for example, aramid fiber) and fibers made of a high elongation material (for example, nylon fiber) has a knot strength due to the characteristics of the high elongation material. Is high, and the elastic modulus is high due to the characteristics of the low-elongation material. Therefore, it is suitable as a material for the reinforcing member 10 having a mesh structure. When the chemical fiber cords are tied together, it may be knotted or knotless, but it is preferable to use knotless from the viewpoint of thinning the member.

  The thickness of the reinforcing cords 11 to 14 is preferably 0.5 mm to 1.5 mm. If this thickness exceeds the upper limit value, the rubber layer becomes thicker and the weight of the tire increases, so the rolling resistance deteriorates.If the thickness falls below the lower limit value, it is necessary to increase the number of cords arranged to secure the same strength. As a result, the density of the joining points becomes too high, which makes it difficult to manufacture the reinforcing member 10.

  Further, the reinforcing member 10 forming the carcass layer 4 is preferably covered with rubber. As a result, the integrity of the reinforcing cords 11 to 14 can be secured and the in-plane bending rigidity of the reinforcing member 10 can be increased.

  With a tire size of 215/55R17, a tread portion that extends in the tire circumferential direction and forms an annular shape, a pair of sidewall portions that are arranged on both sides of the tread portion, and a tire radial direction inner side of these sidewall portions are arranged. In a pneumatic tire having a pair of bead portions and a carcass layer mounted between the pair of bead portions, the carcass layer includes a plurality of reinforcing cords oriented in at least three directions in a region on the bead portion side, Tires of Examples 1 and 2 were manufactured using a reinforcing member (FIGS. 2 and 5) having a net-like structure in which at least three reinforcing cords having different orientations are joined to each other at intersections of these reinforcing cords.

  For comparison, a conventional pneumatic tire having a carcass layer including a plurality of reinforcing cords extending in the tire radial direction between a pair of bead portions was prepared. Further, a tire of a comparative example was prepared in which a carcass layer including a plurality of reinforcing cords extending in the tire radial direction was mounted between a pair of bead portions and two bead reinforcing layers were embedded from the bead portion to the sidewall portion. did.

  The tire weight and steering stability of these test tires were evaluated by the following evaluation methods, and the results are shown in Table 1.

Tire weight:
The weight of each test tire was measured. The evaluation results are shown by an index with the conventional example being 100, using the reciprocal of the measured value. The larger the index value, the lighter the weight.

Steering stability:
Each test tire was mounted on a wheel with a rim size of 17×7J, mounted on a test vehicle with a displacement of 3000 cc, and sensory evaluation was performed by a test driver under an air pressure of 230 kPa. The evaluation results are shown by an index with the conventional example being 100. The larger the index value, the better the steering stability.

  As can be seen from Table 1, the tires of Examples 1 and 2 can increase the tire circumferential rigidity without adding a bead reinforcing layer. Therefore, in comparison with the conventional example, the tire weight is substantially reduced. The steering stability could be improved without increasing. On the other hand, in the tires of Comparative Examples, although the effect of improving the steering stability was recognized, the tire weight was increased accordingly.

DESCRIPTION OF SYMBOLS 1 tread part 2 sidewall part 3 bead part 4 carcass layer 5 bead core 6 bead filler 7 belt layer 8 belt reinforcing layer 10 reinforcing members 11 to 14 reinforcing cords 15 and 16 joint parts

Claims (5)

An annular tread portion extending in the tire circumferential direction, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged on the tire radial inner side of these sidewall portions. In the pneumatic tire in which a carcass layer is mounted between the pair of bead portions, the carcass layer includes a plurality of reinforcing cords oriented in at least three directions in a region on the bead portion side. Use of a reinforcing member having a net-like structure in which at least three reinforcing cords having different orientations are joined to each other at least at some intersections , and the carcass layer processes the reinforcing member having the net-like structure into an endless ring. A pneumatic tire characterized by being molded with .   The pneumatic tire according to claim 1, wherein the at least three reinforcing cords are joined to each other at at least 30% of the intersecting points where at least three reinforcing cords intersect.   The pneumatic tire according to claim 1 or 2, wherein the intersection angle of at least three reinforcing cords joined at the intersection is 15° or more. The pneumatic tire according to any one of claims 1 to 3, wherein the reinforcing cords, characterized in that the knot strength comprises a chemical fiber cord is 1.5 (cN / dtex) or more. The pneumatic tire according to any one of claims 1-4 reinforcing member having the mesh structure, characterized in that it is coated with rubber.

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