JP2019209922A - Pneumatic tire - Google Patents

Abstract

To reduce the weight of a tire while improving in-plane shear rigidity of a belt.SOLUTION: A pneumatic tire 10 includes: a pair of bead cores 12A; a carcass 18 formed so as to astride the pair of bead cores 12A; a reinforcement cord 20A which is arranged outside in a tire radial direction of the carcass 18, extends in a tire circumferential direction and is aligned with a space in a tire width direction; and a resin body 12B which is formed of a resin in an annular shape, covers the reinforcement cord 12A, and is formed with a groove in a tire circumferential direction on outside in the tire width direction of at least one surface of outside and inside in the tire radial direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire provided with a belt layer.

  As a pneumatic tire to be mounted on an automobile, a belt including two or more inclined belt plies configured to include a cord inclined toward the tire circumferential direction on the outer side in the tire radial direction of the carcass, and a belt provided with a reinforcing layer and the like. The structure is general (see, for example, Patent Documents 1 and 2).

JP 2013-244930 A JP 2013-220741 A

  The pneumatic tires of Patent Documents 1 and 2 ensure in-plane shear rigidity by providing two or more inclined belt plies, but it is difficult to reduce the weight of the tire because of the large number of plies and reinforcing layers. It has become.

  In consideration of the above-described facts, the present invention has an object to provide a pneumatic tire that reduces the weight of the tire while improving the in-plane shear rigidity of the belt.

  The pneumatic tire according to claim 1 is disposed on the outer side in the tire radial direction of the carcass, a carcass formed across the pair of bead cores, and extending in the tire circumferential direction, and in the tire width direction. A reinforcing cord arranged at intervals, and a ring formed of a resin, covering the reinforcing cord, and having a groove along the tire circumferential direction at the outer side in the tire width direction on at least one of the outer side and the inner side in the tire radial direction. And a resin annular belt having a formed resin main body.

  In the pneumatic tire according to claim 1, a resin annular belt is disposed on the outer side in the tire radial direction of the carcass. The resin annular belt includes an annular resin main body made of resin and a reinforcing cord covered with the resin main body. The reinforcing cords extend in the tire circumferential direction and are arranged at intervals in the tire width direction. As described above, in the resin annular belt, the resin is arranged between the reinforcing cords arranged at intervals in the tire width direction, so that the in-plane shear rigidity is higher than that of the belt in which the rubber is arranged between the reinforcing cords. Can be obtained. In addition, the weight of the tire can be reduced.

  While high in-plane shear rigidity can be obtained, stress tends to concentrate on the end of the resin annular belt in the tire width direction, but in the present invention, at least one of the outer side and the inner side in the tire radial direction of the resin body Grooves are formed along the tire circumferential direction on the outer side in the tire width direction. By this groove, the outer side portion in the tire width direction of the resin annular belt is easily deformed, and the stress concentration in the outer portion in the tire width direction of the resin annular belt can be reduced. Moreover, since the groove is formed along the tire circumferential direction, deformation in the direction intersecting the tire circumferential direction is suppressed.

  In the pneumatic tire according to claim 2, the groove width of the groove is narrower than the inter-cord pitch of the reinforcing cord in the tire width direction.

  Thus, by making the groove width narrower than the pitch between the cords of the reinforcing cords in the tire width direction, the groove can be formed avoiding the position where the reinforcing cords are arranged closest to the surface in the resin annular belt, The thickness of the resin body covering the reinforcing cord can be ensured.

  In the pneumatic tire according to claim 3, the groove depth of the groove is 1/10 or more and 1/2 or less of the thickness of the resin annular belt.

  By setting the groove depth to 1/10 or more and 1/2 or less of the thickness of the resin annular belt, it is possible to appropriately deform the resin annular belt while alleviating stress concentration in the groove.

  In the pneumatic tire according to claim 4, the groove is formed in at least a part within a range of ½ of the outer side in the tire width direction in the belt half width from the tire equatorial plane to the outer end in the tire radial direction of the resin annular belt. Has been.

  By forming a groove in the half of the width in the tire width direction in the half width of the belt from the tire equator surface of the resin annular belt to the outer end in the tire radial direction, the portion where the groove is formed is easily deformed. Stress concentration at the outer side portion of the annular belt in the tire width direction can be effectively reduced.

  According to the pneumatic tire according to the present invention, both the in-plane shear rigidity of the belt can be secured and the tire weight can be reduced.

It is a half sectional view showing the state where the pneumatic tire concerning this embodiment was cut along the tire width direction and the tire radial direction. FIG. 2 is a partially enlarged view of FIG. 1. It is a partially broken top view of the resin annular belt of the pneumatic tire which concerns on this embodiment.

  A pneumatic tire 10 according to an embodiment of the present invention will be described with reference to the drawings. The pneumatic tire 10 of the present embodiment is a so-called radial tire used for a passenger car, for example. FIG. 1 shows one side of a cut surface (a cross section viewed from the direction along the tire circumferential direction) cut along the tire width direction and the tire radial direction of the pneumatic tire 10. In the drawing, an arrow W indicates the width direction (tire width direction) of the pneumatic tire 10, and an arrow R indicates the radial direction (tire radial direction) of the pneumatic tire 10. The tire width direction here refers to a direction parallel to the rotation axis of the pneumatic tire 10. Further, the tire radial direction refers to a direction orthogonal to the rotation axis of the pneumatic tire 10. Reference sign CL indicates the equator plane (tire equator plane) of the pneumatic tire 10.

  In the present embodiment, the side closer to the rotational axis of the pneumatic tire 10 along the tire radial direction is “inner side in the tire radial direction”, and the side farther from the rotational axis of the pneumatic tire 10 along the tire radial direction is “tire”. “Outside in the radial direction”. On the other hand, the side close to the tire equator plane CL along the tire width direction is described as “inner side in the tire width direction”, and the side far from the tire equator plane CL along the tire width direction is described as “outer side in the tire width direction”.

  Further, in the present embodiment, the grounding end E and the grounding width TW of the tread 30 to be described later are that the pneumatic tire 10 is mounted on a standard rim defined in JATMA YEAR BOOK (2018 version, Japan Automobile Tire Association Standard). In addition, it is filled with 100% of the air pressure (maximum air pressure) corresponding to the maximum load capacity (bold load in the internal pressure-load capacity correspondence table) in the applicable size and ply rating in JATMA YEAR BOOK, The rotation axis is arranged parallel to the flat plate, and the mass corresponding to the maximum load capacity is added. When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  As shown in FIG. 1, a pneumatic tire 10 includes a pair of bead portions 12 in which a bead core 12 </ b> A is embedded, a pair of side portions 14 that extend outward from the pair of bead portions 12 in the tire radial direction, and tires from the side portions 14. The crown portion 16 extends inward in the width direction. A carcass 18 composed of a single carcass ply 18 </ b> A straddles between one bead portion 12 and the other bead portion 12. A resin annular belt 20 is provided on the crown portion 16 on the outer side in the tire radial direction of the carcass 18. A tread 30 is disposed on the outer side of the resin annular belt 20 in the tire radial direction. A plurality of main grooves 32 are formed in the tread 30 along the tire circumferential direction. In FIG. 1, only one side of the tire equatorial plane CL in the pneumatic tire 10 is illustrated.

  The carcass ply 18A is formed by coating a plurality of cords (not shown) extending in the radial direction of the pneumatic tire 10 with a coating rubber (not shown). The material of the cord of the carcass ply 18A is, for example, PET, but may be another conventionally known material.

  The end portion of the carcass ply 18A in the tire width direction is folded back outward in the tire radial direction by a bead core 12A. In the carcass ply 18A, a portion extending from one bead core 12A to the other bead core 12A is called a main body portion 18B, and a portion folded from the bead core 12A is called a folded portion 18C.

  Between the main body portion 18B and the turn-up portion 18C of the carcass ply 18A, a bead filler 12B whose thickness gradually decreases from the bead core 12A toward the outer side in the tire radial direction is disposed. In the pneumatic tire 10, a bead portion 12 is a portion on the inner side in the tire radial direction from the tire radial direction outer end 12C of the bead filler 12B.

  An inner liner 26 made of rubber is arranged inside the tire of the carcass 18, and a side rubber layer 24 made of a rubber material is arranged outside the carcass 18 in the tire width direction.

    As shown in FIG. 2, the resin annular belt 20 includes a reinforcing cord 20A spirally wound in the tire circumferential direction and a resin main body 20B made of a resin material that covers the reinforcing cord 20A. The interval between the reinforcing cords 20A is a pitch P. The resin annular belt 20 can be formed of a ring-shaped ridge obtained by spirally winding a resin-coated cord 20C in which a reinforcing cord 20A is covered with a resin main body 20B. As shown in FIG. 3A, the reinforcing cord 20A is arranged so as to be inclined at an angle θ1 with respect to the tire circumferential direction. In FIG. 3, the extending direction CD of the reinforcing cord 20A is indicated by a one-dot chain line, and the tire circumferential direction S is indicated by a solid line.

  In the present embodiment, one resin-coated cord 20C is spirally wound in the tire circumferential direction to form the resin annular belt 20. However, the reinforcing cord 20A extending along the tire circumferential direction in another configuration is provided. It may be embedded in the resin main body 20B. For example, the resin-coated cord 20C may be formed in a ring shape, and a plurality of ring-shaped resin-coated cords 20C may be formed side by side in the tire width direction. A resin material having a higher tensile elastic modulus than that of the rubber material forming the side rubber layer 24 and the rubber material forming the tread 30 described later is used for the resin main body 20B. The tensile elastic modulus (specified in JIS K7113: 1995) of the resin main body 20B is preferably 100 MPa or more. Moreover, it is preferable that the upper limit of the tensile elasticity modulus of the resin main body 20B shall be 1000 MPa or less. The tensile elastic modulus of the resin main body 20B is particularly preferably in the range of 200 to 700 MPa.

  Examples of the material of the resin main body 20B include thermoplastic resins, thermoplastic elastomers, thermosetting resins, and (meth) acrylic resins, EVA resins, vinyl chloride resins, fluorine resins, silicone resins, and other general-purpose resins. In addition, engineering plastics (including super engineering plastics) can be used. The resin material here does not include vulcanized rubber.

  A thermoplastic resin (including a thermoplastic elastomer) refers to a high molecular compound that softens and flows as the temperature rises and becomes relatively hard and strong when cooled. In the present specification, among these, the material softens and flows with increasing temperature, and becomes relatively hard and strong when cooled, and a high molecular compound having rubber-like elasticity is a thermoplastic elastomer, and the material increases with increasing temperature. Is softened, fluidized, and becomes a relatively hard and strong state when cooled, and a high molecular compound having no rubber-like elasticity is distinguished as a thermoplastic resin that is not an elastomer.

  Thermoplastic resins (including thermoplastic elastomers) include polyolefin-based thermoplastic elastomers (TPO), polystyrene-based thermoplastic elastomers (TPS), polyamide-based thermoplastic elastomers (TPA), polyurethane-based thermoplastic elastomers (TPU), and polyesters. Thermoplastic thermoplastic elastomer (TPC), dynamically crosslinked thermoplastic elastomer (TPV), polyolefin-based thermoplastic resin, polystyrene-based thermoplastic resin, polyamide-based thermoplastic resin, polyester-based thermoplastic resin, etc. Can be mentioned.

  The thermosetting resin refers to a polymer compound that forms and cures a three-dimensional network structure as the temperature rises, and examples thereof include a phenol resin, an epoxy resin, a melamine resin, and a urea resin.

  The reinforcing cord 20A is a steel cord. This steel cord is mainly composed of steel and can contain various trace contents such as carbon, manganese, silicon, phosphorus, sulfur, copper, and chromium.

  As shown in FIG. 2, a groove 24 is formed on the outer side of the resin annular belt 20 in the tire width direction. The grooves 24 are formed on the outer side and the inner side in the tire radial direction of the resin main body 20B. The groove 24 formed on the inner side in the tire radial direction of the resin main body 20B is referred to as an inner groove 24A, and the groove 24 formed on the outer side in the tire radial direction is referred to as an outer groove 24B. The groove 24 is formed in a spiral shape along the extending direction of the reinforcing cord 20A. Similar to the reinforcing cord 20A, the groove 24 is disposed so as to be inclined at an angle θ1 with respect to the tire circumferential direction (see FIG. 3A). Further, the groove 24 is formed between adjacent reinforcing cords 20A in the tire width direction. The groove bottom of the groove 24 has an R shape. The groove width W1 of the groove 24 is narrower than the pitch P of the reinforcing cord 20A. The groove 24 is formed so as to avoid a position where the reinforcing cord 20 </ b> A is closest to the surface of the resin annular belt 20.

  If the range in which the groove 24 is formed is defined as the groove region 22, the groove region 22 is at least the outer side in the tire width direction in the belt half width BW / 2 from the tire equatorial plane CL of the resin annular belt 20 to the outer end in the tire radial direction. It is preferable that it exists in the range of 1/2. Moreover, it is preferable that the groove | channel area | region 22 is arrange | positioned on the outer side of a tire width direction rather than the main groove 32 arrange | positioned on the outermost side of a tire width direction. In addition, the groove area | region 22 exists in the both ends of a tire width direction.

  The depth D1 of the groove 24 is preferably ½ or less of the thickness of the resin main body 20B (resin annular belt 20). Moreover, it is preferable that the depth D1 of the groove | channel 24 is 1/10 or more of the thickness of the resin main body 20B (resin annular belt 20). By setting the depth D1 of the groove 24 to ½ or less of the thickness of the resin main body 20B (resin annular belt 20), the strength of the resin annular belt 20 on the outer side in the tire width direction can be ensured. Moreover, rigidity reduction can be effectively performed by making the depth of the groove | channel 24 into 1/10 or more of the thickness of the resin main body 20B (resin annular belt 20).

  The groove 24 can be formed when the resin annular belt 20 is manufactured. The inner groove 24A on the inner side in the tire radial direction is provided with a convex shape corresponding to the inner groove 24A on the outer peripheral surface of a drum around which the resin-coated cord 20C is spirally wound during resin annular belt molding, and the convex shape is transferred. Can be formed. The outer groove 24B on the outer side in the tire radial direction is provided with a convex shape corresponding to the outer groove 24B on a roller for pressing the resin-coated cord 20C against the drum when the resin-coated cord 20C is wound around the outer peripheral surface of the drum. It can be formed by transferring the convex shape. The inner grooves 24A and the outer grooves 24B can be formed by cutting after the resin annular belt 20 is manufactured.

  The resin annular belt 20 of the present embodiment has an outer diameter at the center in the tire width direction that is larger than the outer diameter at both ends in the tire width direction, and when viewed in a cross section along the tire axis, However, the present invention is not limited to this, and the resin annular belt 20 is formed with a constant diameter and a constant thickness, and is straight when viewed in a cross section along the tire axis. It can also be.

  Specifically, when the pneumatic tire 10 is for a passenger car, the thickness dimension of the resin annular belt 20 of the present embodiment is preferably 0.70 mm or more. The width BW of the resin annular belt 20 is preferably 75% or more and 110% or less with respect to the ground contact width TW (distance between the ground ends E) of the tread 30 measured along the tire axial direction.

  A tread 30 made of a rubber material is disposed on the outer side in the tire radial direction of the resin annular belt 20. Conventionally known rubber materials are used for the tread 30. A main groove 32 for drainage is formed in the tread 30.

(Function, effect)
Next, functions and effects of the pneumatic tire 10 of the present embodiment will be described.

  In the pneumatic tire 10 of the present embodiment, the crown portion 16 of the carcass 18 is reinforced by the resin annular belt 20. Therefore, higher in-plane shear rigidity can be obtained as compared with the case where the rubber is reinforced by the belt in which the rubber is disposed between the reinforcing cords. By ensuring the in-plane shear rigidity of the resin annular belt 20, it is possible to sufficiently generate a lateral force when a slip angle is applied to the pneumatic tire 10, and to ensure steering stability. Responsiveness can also be improved.

  Also, the out-of-plane bending rigidity is secured by the resin annular belt 20, and when a large lateral force is input to the pneumatic tire 10, the buckling of the tread 30 (the surface of the tread 30 undulates and a part thereof is separated from the road surface). Phenomenon).

  While high in-plane shear rigidity is obtained, stress tends to concentrate on the end of the resin annular belt 20 in the tire width direction, but a groove 24 is formed in the groove region 22 of the resin annular belt 20. Therefore, the outer side portion in the tire width direction of the resin annular belt 20 is easily deformed, and the stress concentration in the outer side portion in the tire width direction can be reduced. Moreover, since the groove | channel 24 is formed along the tire circumferential direction, it can suppress the deformation | transformation of the direction which cross | intersects a tire circumferential direction, ie, the deformation | transformation along a tire width direction.

  In the present embodiment, the groove width W1 of the groove 24 is narrower than the inter-cord pitch P of the reinforcing cord 20A in the tire width direction. As a result, the groove 24 can be formed avoiding the position where the reinforcing cord 20A is disposed closest to the surface in the resin annular belt 20, and the thickness of the resin main body 20B covering the reinforcing cord 20A can be ensured. .

  In this embodiment, the groove 24 is formed in a spiral shape along the reinforcing cord 20A. However, the angle of the groove 24 is larger than that of the reinforcing cord 20A with respect to the tire circumferential direction so as to intersect the reinforcing cord 20A. It may be formed in a spiral shape, or may be formed in a spiral shape with a smaller angle with respect to the tire circumferential direction. Further, as shown in FIG. 3B, a plurality of grooves 24 may be formed in an annular shape in the same direction as the tire circumferential direction.

  Moreover, in this embodiment, although formed in both the tire radial direction inner side and the outer side of the resin annular belt 20, you may form only in any one. That is, only one of the inner groove 24A and the outer groove 24B may be formed.

  Further, the grooves 24 may be formed at a finer interval than the pitch P of the reinforcing cord 20A, or may be formed at a larger interval than the pitch P.

10 Pneumatic tire 12A Bead core, 18 Carcass 20 Resin annular belt, 20A Reinforcement cord 20B Resin body, 20C Resin coated cord 22 Groove region, 24 Groove 30 Tread, 32 Main groove P Pitch

Claims (4)

A pair of bead cores;
A carcass formed across the pair of bead cores;
Reinforcement cords arranged outside the carcass in the tire radial direction, extending in the tire circumferential direction and lined up at intervals in the tire width direction, and formed in resin to form an annular shape, covering the reinforcement cord and extending in the tire radial direction A resin annular belt having a resin main body formed with grooves along the tire circumferential direction on the outer side in the tire width direction on at least one side of the outer side and the inner side;
Pneumatic tire with   The pneumatic tire according to claim 1, wherein a groove width of the groove is narrower than a pitch between cords of the reinforcing cord in the tire width direction.   The pneumatic tire according to claim 1 or 2, wherein a groove depth of the groove is 1/10 or more and 1/2 or less of a thickness of the resin annular belt.   The said groove | channel is formed in at least one part in the 1/2 range of the tire width direction outer side in the belt half width from the tire equatorial plane of the said resin annular belt to a tire radial direction outer end. 4. The pneumatic tire according to any one of 3 above.