JP2019209713A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire which can achieve both securing in-plane shear rigidity of a belt and reduction in weight of a tire.SOLUTION: A pneumatic tire 10 includes: a pair of bead cores 12A; a carcass 20 formed so as to astride the pair of bead cores 12A; an annular resin body which is arranged outside in a tire radial direction of the carcass 20 and is formed of a resin; a center belt part 32 which has a cord 34C that extends in a tire circumferential direction and is aligned with a space in a tire width direction and is embedded in the resin body, and is arranged so as to cross a tire equatorial surface CL in a tire width direction; a shoulder belt part 36 which has a cord that extends to outside of the end in the tire width direction of the center belt part 32, and is inclined in a mutual opposite direction with respect to the tire circumferential direction; and a tread 60 which is arranged outside in the tire radial direction of the center belt part 32 and the shoulder belt part 36.SELECTED DRAWING: Figure 1

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 facts, an object of the present invention is to provide a pneumatic tire that achieves both in-plane shear rigidity of the belt and weight reduction of the tire.

  A pneumatic tire according to claim 1 is a pair of bead cores, a carcass formed across the pair of bead cores, an annular resin main body formed of resin disposed on the outer side in the tire radial direction of the carcass, and A central belt portion that extends in the tire circumferential direction and has a cord embedded in the resin main body and spaced apart in the tire width direction, and is disposed across the tire equatorial plane in the tire width direction; A plurality of layers of shoulder belt portions having cords extending outward from the tire width direction end portion of the central belt portion and inclined in opposite directions with respect to the tire circumferential direction, the central belt portion and the shoulder belt portion And a tread disposed on the outer side in the tire radial direction.

  In the pneumatic tire according to claim 1, the central belt portion is disposed on the outer side in the tire radial direction of the carcass. The central belt portion has an annular resin main body formed of resin, and a cord extending in the tire circumferential direction and arranged in the tire width direction at intervals in the tire main body, and embedded in the resin main body. Is arranged across the tire width direction. In the central belt portion, since the resin is disposed between the cords arranged at intervals in the tire width direction, a higher in-plane shear rigidity can be obtained as compared with a belt in which rubber is disposed between the cords. In addition, the weight of the tire can be reduced. Moreover, the shoulder belt part extended outside the tire width direction end part of the central belt part has a plurality of layers of cords inclined in opposite directions with respect to the tire circumferential direction. The shoulder belt portion has cords that are inclined in directions opposite to each other with respect to the tire circumferential direction, and is more easily expanded and contracted in the tire circumferential direction than a cord extending in the tire circumferential direction. Can be relaxed.

  In the pneumatic tire according to claim 2, the end portion in the tire width direction of the central belt portion is disposed on the outer side in the tire width direction with respect to the main groove on the outermost side in the tire width direction formed on the tread.

  According to the pneumatic tire of the second aspect, since the central belt portion is disposed to the outer side in the tire width direction than the main groove, high in-plane shear rigidity can be obtained on the tread surface of the tread having a high contact pressure. .

  In the pneumatic tire according to a third aspect, the shoulder belt portion is arranged so as to overlap the central belt portion in the tire width direction.

  Thus, by arranging the shoulder belt portion and the central belt portion so as to overlap each other in the tire width direction, the shoulder belt portion can be easily continued to extend outward from the end portion in the tire width direction of the central belt portion. be able to.

  In the pneumatic tire according to a fourth aspect, the shoulder belt portion is disposed so as to overlap with the central belt portion in the tire radial direction.

  Thus, by arranging the shoulder belt portion and the central belt portion so as to overlap in the tire radial direction, an increase in the thickness of the belt can be suppressed, and the weight of the tire can be 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 a 1st 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 the partially broken view which looked at some belt layers of the pneumatic tire concerning a 1st embodiment from the tire diameter direction outside. It is a partial enlarged view of the pneumatic tire which concerns on the modification of 1st Embodiment. It is a partially expanded view of the pneumatic tire which concerns on the other modification of 1st Embodiment. The pneumatic tire according to the second embodiment is aligned along the tire width direction and the tire radial direction. It is the partially broken view which looked at some belt layers of the pneumatic tire concerning a 2nd embodiment from the tire diameter direction outside.

[First Embodiment]
A pneumatic tire 10 (hereinafter referred to as “tire 10”) according to a first embodiment of the present invention will be described with reference to the drawings. The 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 tire 10. In the figure, an arrow W indicates the width direction of the tire 10 (tire width direction), and an arrow R indicates the radial direction of the tire 10 (tire radial direction). The tire width direction here refers to a direction parallel to the rotation axis of the tire 10. The tire radial direction refers to a direction orthogonal to the rotation axis of the tire 10. Reference sign CL indicates the equator plane of the tire 10 (tire equator plane).

  In the present embodiment, the side closer to the rotation axis of the tire 10 along the tire radial direction is “inner side in the tire radial direction”, and the side farther from the rotation axis of the tire 10 along the tire radial direction is “outer side in the tire radial direction”. It describes. 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”. In the figure, a direction from the tire equatorial plane CL toward the outer side in the tire width direction is indicated by an arrow OUT.

  FIG. 1 shows a tire 10 when it is assembled to a rim 30 that is a standard rim and filled with standard air pressure. Here, the “standard rim” refers to a rim defined in JATMA YEAR BOOK (2018 edition, Japan Automobile Tire Association Standard). Further, the contact end E and the contact width TW of the tread 60 to be described later are the maximum load capacity in the applied size / ply rating in the JATMA YEAR BOOK when the tire 10 is mounted on the standard rim (bold characters in the internal pressure-load capacity correspondence table) Filled with 100% of the air pressure (maximum air pressure) corresponding to the load), placed in a stationary state so that the rotation axis is parallel to the horizontal flat plate, and added the mass corresponding to the maximum load capacity It is a thing when. 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, the 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 in the tire radial direction from the pair of bead portions 12, and a tire width direction from the side portions 14. A crown portion 16 extending inward. A carcass 20 including one carcass ply 22 straddles between one bead portion 12 and the other bead portion 12. A belt layer 30 is provided on the crown portion 16 on the outer side in the tire radial direction of the carcass 20. A tread 60 is provided on the outer side of the belt layer 30 in the tire radial direction. In FIG. 1, only one side of the tire equatorial plane CL in the tire 10 is illustrated.

  The carcass ply 22 is formed by coating a plurality of cords (not shown) extending in the radial direction of the tire 10 with a coating rubber (not shown). The material of the cord of the carcass ply 22 is, for example, PET, but may be another conventionally known material.

  The end portion of the carcass ply 22 in the tire width direction is folded back outward in the tire radial direction by a bead core 12A. In the carcass ply 22, a portion extending from one bead core 12A to the other bead core 12A is called a main body portion 22A, and a portion folded from the bead core 12A is called a folded portion 22B.

  Between the main body portion 22A and the turn-up portion 22B of the carcass ply 22, a bead filler 18 whose thickness gradually decreases from the bead core 12A toward the outer side in the tire radial direction is disposed. In the tire 10, a bead portion 12 is a portion on the inner side in the tire radial direction from the outer end 18 </ b> A in the tire radial direction of the bead filler 18.

  An inner liner 26 made of rubber is arranged inside the tire of the carcass 20, and a side rubber layer 24 made of rubber material is arranged outside the carcass 20 in the tire width direction.

  A belt layer 30 is disposed on the crown portion 16 on the outer side in the tire radial direction of the carcass 20. As shown in FIG. 2, the belt layer 30 includes a central belt portion 32 and a shoulder belt portion 36. The central belt portion 32 is disposed across the tire equatorial plane CL in the tire width direction, and a ring-shaped ridge formed by spirally winding one resin-coated cord 34 in the tire circumferential direction ( )). The central belt portion 32 has an annular shape as a whole, and a coating resin 34S described later constitutes an annular resin body in the present invention, and a reinforcing cord 34C constitutes a cord embedded in the resin body in the present invention. doing.

  The resin-coated cord 34 is configured by coating a reinforcing cord 34C with a coating resin 34S. In the present embodiment, the two reinforcing cords 34 </ b> C are arranged apart from each other and covered with the coating resin 34 </ b> S to form the resin-coated cord 34. The cross section of the resin-coated cord 34 has a parallelogram shape whose end face in the width direction is inclined with respect to the tire radial direction. The coating resins 34S adjacent to each other in the tire width direction are integrally joined by heat welding, an adhesive, or the like. One end and the other end of the resin-coated cord 34 wound in a spiral are arranged at different positions in the tire circumferential direction.

  The width BMW of the central belt portion 32 measured along the tire axial direction is preferably 75% or more with respect to the ground contact width TW (distance between the ground end E) of the tread 60 measured along the tire axial direction. . Further, the upper limit of the width BMW of the central belt portion 32 is preferably 110% with respect to the ground contact width TW.

  The central belt portion 32 is joined to the outer peripheral surface of the carcass 20 disposed on the inner side in the tire radial direction via rubber or an adhesive. In this embodiment, it joins via the rubber | gum 32G1 which fills the level | step difference 30D1 of the center belt part 32 and the shoulder belt part 36. FIG.

  The central belt portion 32 is formed with a constant diameter and a constant thickness, and is straight when viewed in a cross section along the tire axis. The central belt portion 32 is not limited to this, and the outer diameter of the central portion in the tire width direction is larger than the outer diameter of both ends in the tire width direction, and the tire width when viewed in a cross section along the tire axis. It can also be made into the circular arc shape which a direction center part protrudes on the tire radial direction outer side.

  For the covering resin 34S, a rubber material constituting the side rubber layer 24 and a resin material having a higher tensile elastic modulus than the rubber material constituting the tread 60 described later are used. The tensile modulus of elasticity (specified in JIS K7113: 1995) of the coating resin 34S is preferably 50 MPa or more. The upper limit of the tensile modulus of the coating resin 34S is preferably 1000 MPa or less. The tensile elastic modulus of the coating resin 34S is particularly preferably in the range of 200 to 500 MPa.

  Examples of the material of the coating resin 34S 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.

  Further, the reinforcing cord 34C in the central belt portion 32 of the present embodiment is a steel cord. The steel cord is mainly composed of steel and can contain various trace contents such as carbon, manganese, silicon, phosphorus, sulfur, copper, and chromium.

  The embodiment of the present invention is not limited to this, and as the reinforcing cord 34C in the central belt portion 32, a monofilament cord or a cord obtained by twisting a plurality of filaments can be used instead of the steel cord. Further, organic fibers such as aramid, carbon, and the like may be used. Various designs can be adopted for the twist structure, and various cross-sectional structures, twist pitches, twist directions, and distances between adjacent filaments can be used. Furthermore, it is possible to adopt a cord in which filaments of different materials are twisted together, and the cross-sectional structure is not particularly limited, and various twisted structures such as single twist, layer twist, and double twist can be adopted.

  The thickness dimension of the central belt portion 32 of the present embodiment is preferably larger than the diameter dimension of the reinforcing cord 34C. In other words, it is preferable that the reinforcing cord 34C is completely embedded in the coating resin 34S. Specifically, when the tire 10 is for a passenger car, the thickness dimension of the central belt portion 32 is preferably 0.70 mm or more.

  FIG. 3 shows a partially enlarged view of the belt layer 30 as viewed from the direction along the tire radial direction. As shown in FIG. 3, the resin-coated cord 34 is wound at an angle θ1 with respect to the tire circumferential direction (the direction indicated by the arrow S in FIG. 3). The angle θ1 is set to 2 ° or less in the present embodiment.

  The shoulder belt portion 36 is disposed so as to extend from both ends of the central belt portion 32 in the tire width direction. The shoulder belt portion 36 is disposed so as to overlap in the tire width direction on the inner side in the tire radial direction of the central belt portion 32. The inner end 36 </ b> A in the tire width direction of the shoulder belt portion 36 is disposed closer to the tire equatorial plane CL than the outer end 32 </ b> A in the tire width direction of the central belt portion 32. The outer end in the tire width direction of the shoulder belt portion 36 is disposed on the outer side in the tire width direction than the outer end in the tire width direction of the central belt portion 32. The upper limit of the width BSW of the shoulder belt portion 36 is preferably 110% with respect to the ground contact width TW.

  The shoulder belt portion 36 includes a first belt ply 37 disposed on the inner side in the tire radial direction and a second belt ply 38 disposed on the outer side in the tire radial direction of the first belt ply 37. The first belt ply 37 is formed by coating a plurality of belt cords 37C arranged in parallel with each other with a coating resin 37S. The belt cords 37C are arranged in parallel to each other so as to be inclined at an angle θ2 with respect to the tire circumferential direction. The second belt ply 38 is obtained by coating a plurality of belt cords 38C arranged in parallel with each other with a coating resin 38S. The belt cords 38C are arranged in parallel to each other so as to be inclined at an angle θ3 with respect to the tire circumferential direction.

  As the belt cords 37C and 38C, known cords such as steel cords and organic fiber cords can be used. Examples of organic fiber cords include nylon cords and aromatic polyamide cords.

  The angle θ2 and the angle θ3 are angles inclined in directions opposite to each other with respect to the tire circumferential direction, and the belt cord 37C and the belt cord 38C are arranged so as to cross each other. The belt ply 38 is joined by heat welding, and the first belt ply 37 and the second belt ply 38 form a two-layer cross belt layer as a shoulder belt portion. The angles θ2 and θ3 are not particularly limited, but can be set to 30 ° to 80 ° with respect to the tire circumferential direction S, for example. The angle θ2 and the angle θ3 may be the same angle or different angles.

  The first belt ply 37 of the shoulder belt portion 36 is joined to the outer peripheral surface of the carcass 20 disposed on the inner side in the tire radial direction via rubber or an adhesive. As for the 2nd belt ply 38 of the shoulder belt part 32, the tire width direction inner side is joined to the tire radial direction inner peripheral surface of the center belt part 32 by heat welding, an adhesive agent, etc. in the tire radial direction outer side. Further, the second belt ply 38 is joined to the inner peripheral surface of the side rubber layer 24 via an adhesive agent on the outer side in the tire width direction than the central belt portion 32.

  A tread 60 made of a rubber material is disposed outside the belt layer 30 in the tire radial direction. Conventionally known rubber materials are used for the tread 60. A main groove 62 for drainage is formed in the tread 60. The outer end in the tire radial direction of the central belt portion 32 is disposed on the outer side in the tire width direction with respect to the main groove 62 disposed on the outermost side in the tire width direction. Further, the inner end in the tire radial direction of the shoulder belt portion 36 is also arranged on the outer side in the tire width direction than the main groove 62 arranged on the outermost side in the tire width direction.

  In the present embodiment, the inner end portion of the shoulder belt portion 36 is arranged and overlapped on the inner side in the tire radial direction of the central belt portion 32. However, as shown in FIG. May be arranged on the outer side in the tire radial direction of the central belt portion 32 to overlap each other. In this case, the inner side in the tire radial direction of the central belt portion 32 can be directly arranged on the outer side in the tire radial direction of the carcass ply 22, and the shoulder belt portion 36 between the central belt portion 32 and the outer side in the tire width direction can be disposed. The step 30D2 can be filled with rubber 32G2.

  Further, as shown in FIG. 5, the inner end portion of the first belt ply 37 in the shoulder belt portion 36 is disposed inside the central belt portion 32 in the tire radial direction, and the inner end portion of the second belt ply 38 is arranged. The central belt portion 32 may be arranged outside the tire radial direction and overlapped. In this case, the first belt ply 37 and the second belt ply 38 can be welded outside the central belt portion 32 in the tire width direction.

  In the present embodiment, the first belt ply 37 and the second belt ply 38 of the shoulder belt portion 36 are belt cords coated with a coating resin 38S. However, instead of the coating resin, the belt cord is coated with rubber. A thing may be used.

  In the present embodiment, one resin-coated cord 34 is spirally wound in the tire circumferential direction to form the central belt portion 32. However, a reinforcing cord 34C extending along the tire circumferential direction in another configuration is provided. It may be embedded in the coating resin 34S. For example, the resin-coated cord 34 may be formed in a ring shape, and a plurality of ring-shaped resin-coated cords 34 may be formed side by side in the tire width direction.

(Function, effect)

  Next, functions and effects of the tire 10 of the present embodiment will be described.

  In the tire 10 of the present embodiment, the crown portion 16 of the carcass 20 is reinforced by a central belt portion 32 around which a resin-coated cord 34 in which a reinforcing cord 34C wound in a spiral shape is coated with a coating resin 34S is wound. Yes. Therefore, a high in-plane shear rigidity can be obtained as compared with a belt in which rubber is disposed between the reinforcing cords. By ensuring the in-plane shear rigidity of the belt layer 30, it is possible to sufficiently generate a lateral force when a slip angle is applied to the tire 10, to ensure steering stability, and to respond. Can also be improved.

  Further, the out-of-plane bending rigidity is secured by the central belt portion 32 around which the resin-coated cord 34 is wound, and when a large lateral force is input to the tire 10, the tread 60 buckling (the surface of the tread 60 is undulated, (A phenomenon in which a part is separated from the road surface) can be suppressed.

  A shoulder belt portion 36 is disposed outside the outer end portion in the tire width direction of the central belt portion 32. The shoulder belt portion 36 is formed as a two-layer crossing layer in which reinforcing cords that are inclined in opposite directions with respect to the tire circumferential direction are interlaced, and is more easily expanded and contracted in the tire circumferential direction than a cord extending in the tire circumferential direction. ing. Therefore, the belt layer 30 can easily follow the deformation of the end portion in the tire width direction when the tread 60 is grounded, and the stress concentration at the end portion in the tire width direction of the belt layer 30 can be reduced.

  Further, in the tire 10 of the present embodiment, the end portion in the tire width direction of the central belt portion 32 is disposed on the outer side in the tire width direction than the main groove 62 on the outermost side in the tire width direction formed on the tread 60. Accordingly, high in-plane shear rigidity can be obtained on the tread surface of the tread 60 having a high contact pressure (the tread surface on the inner side in the tire width direction than the main groove 62 on the outer side in the tire width direction).

  Further, in the tire 10 of the present embodiment, the shoulder belt portion 36 and the central belt portion 32 are disposed overlapping in the tire width direction, so that the shoulder belt portion 36 and the central belt portion 32 are easily continuous. Thus, the shoulder belt portion 36 can be extended outward from the end portion of the central belt portion 32 in the tire width direction.

[Second Embodiment]
A pneumatic tire 50 (hereinafter referred to as “tire 50”) according to a second embodiment of the present invention will be described with reference to the drawings. In addition, about the part similar to 1st Embodiment, the code | symbol same as 1st Embodiment is attached | subjected and the detailed description is abbreviate | omitted.

  The tire 50 of this embodiment includes a belt layer 40 instead of the belt layer 30. The configuration other than the belt layer 40 is the same as that of the first embodiment.

  The belt layer 40 has a central belt portion 32 and a shoulder belt portion 42. The shoulder belt portion 42 is formed by laminating a first belt ply 47 and a second belt ply 48. The first belt ply 47 and the second belt ply 48 have the same shape as the first belt ply 37 and the second belt ply 38 of the first embodiment, and the belt cord 37C of the first belt ply 37, the coating resin 37S, Corresponding to the belt cord 38C and coating resin 38S of the two belt plies 38, the belt cord 47C and coating resin 47S of the first belt ply 47, the belt cord 48C of the second belt ply 48, and the coating resin 48S are provided.

  The shoulder belt portion 42 is disposed such that the inner end in the tire width direction is in contact with the outer end in the tire width direction of the central belt portion 32 and extends from the outer end in the tire width direction of the central belt portion 32. The shoulder belt portion 42 is disposed so as to overlap with the central belt portion 32 in the tire radial direction.

  The first belt ply 44 and the second belt ply 46 are joined by heat welding. The first belt ply 44 and the second belt ply 46 and the central belt portion 32 are joined by heat welding. In addition, these joining may be joining by an adhesive instead of heat welding.

  The central belt portion 32 and the shoulder belt portion 42 are joined to the outer peripheral surface of the carcass 20 via rubber or an adhesive.

  Also in the tire 50 of the present embodiment, the same effect as in the first embodiment can be obtained. Furthermore, by arranging the shoulder belt portion 42 and the central belt portion 32 so as to overlap in the tire radial direction, an increase in the thickness of the belt layer 50 can be suppressed, and the weight of the tire can be reduced.

10, 50 Pneumatic tire 12A Bead core, 20 Carcass 32 Central belt part 34C Reinforcement cord (cord), 34S Coating resin (resin body)
36 Shoulder belt section 37C Belt cord (code), 38C Belt cord (code)
42 shoulder belt portion 60 tread, 62 main groove

Claims (4)

A pair of bead cores;
A carcass formed across the pair of bead cores;
An annular resin main body formed of resin disposed on the outer side in the tire radial direction of the carcass, and a cord that extends in the tire circumferential direction and is arranged at intervals in the tire width direction and embedded in the resin main body. And a central belt portion arranged across the tire equatorial plane in the tire width direction,
A plurality of layers of shoulder belt portions having cords extending outward from the tire width direction end portion of the central belt portion and inclined in directions opposite to each other with respect to the tire circumferential direction;
A tread disposed on the outer side in the tire radial direction from the central belt portion and the shoulder belt portion;
Pneumatic tire with   2. The pneumatic tire according to claim 1, wherein an end portion in the tire width direction of the central belt portion is disposed on the outer side in the tire width direction with respect to a main groove on the outermost side in the tire width direction formed on the tread.   The pneumatic tire according to claim 1, wherein the shoulder belt portion is disposed so as to overlap with the central belt portion in a tire width direction.   The pneumatic tire according to claim 1, wherein the shoulder belt portion is disposed so as to overlap the central belt portion in a tire radial direction.