JP2017030711A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of increasing in-plane bending rigidity while properly maintaining flexibility to out-of-plane deformation of a reinforcement member used for a carcass layer, and thereby capable of increasing tire circumferential rigidity without relying on an additional bead reinforcement layer.SOLUTION: A pneumatic tire comprises a tread part 1 extending in a tire circumferential direction to form an annular shape, a pair of sidewall parts 2 arranged on both sides of the tread part 1, a pair of bead parts 3 arranged on the inside in the tire radial direction of the sidewall parts 2, and a carcass layer 4 installed between the pair of the bead parts 3. The pneumatic tire uses a reinforcement member 10, as the carcass layer 4, including a plurality of reinforcement cords 11 to 14 oriented in at least three directions in a region on the side of the bead parts 3, and having a network structure in which at least the three reinforcement cords 11 to 14 with different orientation directions at at least some intersections of the reinforcement cords 11 to 14 are joined to each other.SELECTED DRAWING: Figure 2

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 in the carcass layer. It relates to a pneumatic tire, which makes it possible to increase the tire circumferential rigidity without depending on an additional bead reinforcement 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, but since each reinforcing cord is substantially independent, the contribution to the tire circumferential rigidity is small. Therefore, for example, when the tire circumferential rigidity is increased for the purpose of improving steering stability, it is generally performed to add a bead reinforcement layer from the bead portion to the sidewall portion (for example, Patent Documents 1 to 3). reference).

  However, adding a bead reinforcement layer increases the tire weight accordingly. Therefore, depending on the additional bead reinforcement layer, increasing the tire circumferential rigidity is not always the best policy.

JP 2010-221920 A JP2013-35362A JP 2014-227149 A

  It is an object of the present invention to increase the in-plane bending stiffness while maintaining good flexibility against out-of-plane deformation of the reinforcing member used in the carcass layer, thereby relying on an additional bead reinforcing layer It is an object of the present invention to provide a pneumatic tire that can increase the circumferential rigidity of the tire without any problem.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a tread portion that extends in the tire circumferential direction to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and the sidewall portions. A pneumatic tire having a carcass layer mounted between the pair of bead portions, the carcass layer serving as at least three directions in the region on the bead portion side. A reinforcing member having a network structure including a plurality of reinforcing cords oriented to each other and having at least three reinforcing cords having different orientation directions joined to each other at at least a part of intersections of the reinforcing cords is used. Is.

  In the present invention, the reinforcing member used for the carcass layer includes a plurality of reinforcing cords oriented in at least three directions in the region on the bead portion side, and the orientation directions are different at least at the intersections of at least some of the reinforcing cords. Since it has a network structure in which three reinforcing cords 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.

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

  In the present invention, it is preferable that at least three reinforcement cords are joined to each other at at least 30% of intersections where at least three reinforcement cords intersect. Thereby, the effect which raises in-plane bending rigidity can fully be acquired.

  Moreover, it is preferable that the crossing angle of at least three reinforcing cords joined at the crossing points is 15 ° or more. Thereby, the effect which raises in-plane bending rigidity can fully be acquired.

  The carcass layer is preferably formed by processing a reinforcing member having a network structure into an endless annular shape. Thereby, durability of a tire becomes favorable.

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

  The reinforcing member having the network structure is preferably 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 meridian sectional drawing which shows the pneumatic tire which consists of 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 this invention. It is explanatory drawing which shows the deformation | transformation mechanism of the reinforcement member which has the network structure which mutually joined at least 3 reinforcement cords from which an orientation direction differs in the intersection location of a reinforcement cord. It is explanatory drawing which shows the deformation | transformation mechanism of the reinforcement member which has the network structure which mutually joined two reinforcement cords from which an orientation direction differs in the intersection location of a reinforcement cord. 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 sectional view showing a pneumatic tire according to another 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 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 includes a tread portion 1 that extends in the tire circumferential direction and has an annular shape, and a pair of sidewall portions 2, 2 disposed on both sides of the tread portion 1. And a pair of bead portions 3 and 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 network structure, which will be described later, and is folded from the inside of the tire to the outside around the bead cores 5 arranged in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross-section is disposed 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 is disposed so that the reinforcing cords cross 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 a range of, for example, 10 ° to 40 °. A steel cord is preferably used as the reinforcing cord of the belt layer 7. For the purpose of improving high-speed durability, 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 is disposed on the outer peripheral side of the belt layer 7. Yes. 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 network structure includes a plurality of reinforcing cords 11 to 14 oriented in four directions. That is, the reinforcing cord 11 extends in parallel with the tire width direction W over the entire region in the tire width direction W, and the reinforcing cord 12 extends in parallel with the tire circumferential direction C only in a region adjacent to the bead core 5. Extends so as to incline to one side with respect to 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 with respect to the tire width direction W only in the region on the bead portion 3 side. Extends to be. The tire width direction W is a direction in the sheet-like reinforcing member 10, but is recognized as a tire radial direction in a 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 orientation directions are integrally joined to form a plurality of joint portions 15.

  The material of the reinforcing cords 11 to 14 is not particularly limited, and a chemical fiber cord or a steel cord 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 cord 12, and steel for the reinforcing cord 11 A structure using chemical fiber cords for the reinforcing cords 12 to 14 while using the cord, and a structure using chemical fiber cords for the reinforcing cords 13 and 14 while using the steel cords for the reinforcing cords 11 and 12 are mentioned. it can.

  The joining method of the reinforcement cords 11-14 is not specifically limited, A various method is employable. In the case of a chemical fiber cord, the joint 15 is formed so that the cords form nodal points, or the fiber bundles (yarns) cross each other without the cords forming no nodes. Can be formed, the joints 15 can be formed by welding the cords, or the joints 15 can be formed by bonding the cords together. In the case of a steel cord, the joint 15 is formed so that both filaments intersect each other without forming a knot between the cords, the joint 15 is formed by welding the cords, The bonding portion 15 can be formed by bonding. In any case, it is necessary that the cords are integrally joined at the intersection so that the positions of each other are regulated.

  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 a part of intersections of the reinforcing cords 11 to 14. Since it has a network structure in which at least three reinforcing cords 11 to 14 having different orientation directions are joined to each other, the in-plane bending rigidity can be enhanced while maintaining the flexibility with respect to the out-of-plane deformation.

  FIG. 3 shows a deformation mechanism of a reinforcing member having a network structure in which at least three reinforcing cords having different orientation directions are joined to each other at the intersection of the reinforcing cords, and FIG. 4 shows two different orientation directions at the reinforcing cord intersections. The deformation | transformation mechanism of the reinforcement member which has the network structure which mutually joined the reinforcement cord of this is shown. As shown in FIG. 4, the reinforcing member 10 </ b> A having a network structure in which two reinforcing cords 11 and 12 having different orientation directions are joined to each other at the intersection of the reinforcing cords 11 and 12 to form a joint portion 16 When force is applied in the direction, it will deform like a pantograph. On the other hand, as shown in FIG. 3, a reinforcement having a network structure in which at least three reinforcement cords 11 to 14 having different orientation directions are joined to each other at intersections of the reinforcement cords 11 to 14 to form a joint portion 15. The member 10 has a planar truss structure, hardly deforms 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 above-described network structure is used as the carcass layer 4, it depends on the additional bead reinforcing layer. Thus, the tire circumferential rigidity can be increased without increasing the steering stability without substantially increasing the tire weight. The reinforcing member 10 has a network structure in which at least three reinforcing cords 11 to 14 having different orientation directions are joined to each other in the region on the bead portion 3 side, but the network structure is formed in the region on the tread portion 1 side. Since it does not have, it can be expanded in the tire molding process. From such a viewpoint, it is preferable that the reinforcing member 10 does not have the joint point 15 on the outer side in the tire radial direction from the tire maximum width position.

  In the pneumatic tire, at least three reinforcement cords 11 to 14 are joined to each other at all intersections where at least three reinforcement cords 11 to 14 intersect, but at least three reinforcement cords 11 to 14 are joined. It is desirable that at least three reinforcing cords 11 to 14 be joined to each other at at least 30% of the intersections where the crossings intersect, more preferably at least 50% (most preferably 70% or more). . Thereby, the effect which raises in-plane bending rigidity can fully be acquired. If this ratio is too small, the effect of improving the in-plane bending stiffness is reduced.

  In the pneumatic tire described above, the intersection angle of at least three reinforcing cords 11 to 14 joined at the intersection is 15 ° or more, and more preferably 20 ° to 75 °. Thereby, the effect which raises in-plane bending rigidity can fully be acquired. If this crossing angle is too small, the effect of improving the in-plane bending stiffness is reduced. 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. In FIG. 5, at least three reinforcing cords 11 to 14 are integrally joined at an intersection where at least three reinforcing cords 11 to 14 intersect to form a plurality of joints 15. At least at a part of the intersection where the cords 13 and 14 intersect, the two reinforcing cords 13 and 14 are integrally joined to form a plurality of joints 16. And the area | region in which the junction parts 15 and 16 of the reinforcement member 10 were formed is 4 each toward the tire radial direction outer side (in the planar view of FIG. 5 from the position of the bead core 5 on the tire width direction both sides). When divided into two regions A1 to A4, the density of the joints 15 and 16 in these regions A1 to A4 is set so as to increase toward the inner side in the tire radial direction. However, the densities of the joints 15 and 16 in the regions A1 and A2 are equivalent. According to such an arrangement, the in-plane bending rigidity can be effectively increased without hindering deformation of the reinforcing member 10 constituting 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 from the inside to the outside of the tire around the bead core 5 disposed in each bead portion 3, and the folded end portion is disposed 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 such a 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. At least a part of the intersections of -14 has a network structure in which at least three reinforcing cords 11-14 having different orientation directions are joined to each other. That is, the reinforcing cord 11 extending in the tire width direction W extends over the entire region in the tire width direction W, but the network structure including the joint portion 15 is selectively formed only in the region corresponding to the bead portion 3. Yes. In this case as well, the in-plane bending rigidity can be increased 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 network structure into an endless annular shape. That is, the reinforcing member 10 can be knitted into a ring shape. In this case, the durability of the pneumatic tire is improved. Of course, the carcass layer 4 can 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 a net-like structure can be handled in the same manner as a conventional carcass member, it is easy to manufacture a pneumatic tire.

  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 hook strength of 2.5 ( It is desirable to use a chemical fiber cord that is equal to or higher than cN / dtex). 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 hook strength is 3.5 (cN / dtex) or more. More preferably, the tensile strength is 4.0 (cN / dtex) or more, the nodule strength is 3.0 (cN / dtex) or more, and the hook strength is 5.0 (cN / dtex) or more, and most preferably 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 hook strength is 20 (cN / dtex) or less, and the tensile strength is 15 (cN / dtex) or less. Is realistic. The knot strength and hook strength are measured in accordance with 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, the material can be made different depending on the extension direction of the cord. In addition, composite cords made by twisting fibers made of low elongation materials (for example, aramid fibers) and fibers made of high elongation materials (for example, nylon fibers) have knot strength due to the characteristics of the high elongation materials. Since the elastic modulus increases due to the characteristics of the low elongation material, it is suitable as a material for the reinforcing member 10 having a network structure. Further, when the chemical fiber cords are connected to each other, the knots may be knotted or knotless, but it is preferable that knots are knotted 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, the rubber layer becomes thicker and the tire weight increases, so the rolling resistance deteriorates.If the thickness is less than the lower limit, the number of cords must be increased in order to ensure the same strength. As a result, the density of the joining points becomes too high, making it difficult to manufacture the reinforcing member 10.

  The reinforcing member 10 constituting the carcass layer 4 is preferably covered with rubber. Thereby, the integrity of the reinforcement cords 11-14 can be ensured and the in-plane bending rigidity of the reinforcement member 10 can be improved.

  The tire size is 215 / 55R17 and extends in the tire circumferential direction to form an annular tread portion, a pair of sidewall portions disposed on both sides of the tread portion, and the sidewall portions disposed on the inner side in the tire radial direction. 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 the region on the bead portion side, Tires of Examples 1 and 2 using a reinforcing member (FIGS. 2 and 5) having a network structure in which at least three reinforcing cords having different orientation directions were joined to each other at the intersections of these reinforcing cords were manufactured.

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

  For these test tires, the tire weight and steering stability 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 as an index with the conventional example being 100, using the reciprocal of the measured value. A larger index value means lighter weight.

Steering stability:
Each test tire was assembled on a wheel having a rim size of 17 × 7 J, mounted on a test vehicle having a displacement of 3000 cc, and sensory evaluation was performed by a test driver under the condition of an air pressure of 230 kPa. The evaluation results are shown as 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, so that the tire weight is substantially reduced in comparison with the conventional example. Steering stability could be improved without increasing it. On the other hand, in the tire of the comparative example, although the effect of improving the steering stability was recognized, the tire weight was increased accordingly.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt reinforcement layer 10 Reinforcement member 11-14 Reinforcement cords 15 and 16 Joining part

Claims (6)

  An annular tread portion extending in the tire circumferential direction, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the inner side in the tire radial direction of the sidewall portions. A 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. A pneumatic tire using a reinforcing member having a network structure in which at least three reinforcing cords having different orientation directions are joined to each other at least at some intersections.   2. The pneumatic tire according to claim 1, wherein the at least three reinforcement cords are joined to each other at an intersection of at least 30% of intersections where at least three reinforcement cords intersect.   The pneumatic tire according to claim 1 or 2, wherein an 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 carcass layer is formed by processing a reinforcing member having the network structure into an endless annular shape.   The pneumatic tire according to claim 1, wherein the reinforcing cord includes a chemical fiber cord having a knot strength of 1.5 (cN / dtex) or more.   The pneumatic tire according to claim 1, wherein the reinforcing member having a net-like structure is covered with rubber.

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