Tire

Abstract

Provided is a tire (2) that can achieve weight reduction while suppressing a decrease in strength of a carcass without impairing appearance quality. The tire (2) includes a pair of beads (10), a carcass (12), an inner liner (20), and a separation layer (22) between the carcass (12) and the inner liner (20). The carcass (12) is composed of one carcass ply (42). The carcass ply (42) is composed of a plurality of carcass cords (44) and a coating rubber (46). The total fineness of the carcass cords (44) is 6000 dtex or more and 9000 dtex or less. The separation layer (22) is between the first bead (10) and the second bead (10). The ratio (ta / td) of the thickness ta of the coating rubber (46) between the separation layer (22) and the carcass cords (44) to the thickness td of the separation layer (22) is 0.2 or more and 0.6 or less.

Description

Technical Field

[0001] This invention relates to a tire. More specifically, this invention relates to a tire mounted on a passenger car. Background Technology

[0002] The tire carcass consists of at least one carcass ply. The carcass ply contains multiple carcass cords arranged side-by-side. Carcass cords typically use cords with a 1100 dtex / 2 or 1670 dtex / 2 cord structure. The inner liner that forms the inner surface of the tire is located inside the carcass.

[0003] During the tire vulcanization process, the unvulcanized tire (hereinafter referred to as a green tire) is pressed onto a mold by an air bladder located inside it. At this time, the inner liner sometimes merges between the tire carcass cords. This creates a grooved pattern on the inner surface of the tire (also known as groove opening).

[0004] Ridge breakage affects the appearance quality of tires. Various studies have been conducted to prevent rigging (e.g., Patent Document 1 below).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2012-158156 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] To meet the requirements for lightweighting, research is underway to use a single tire carcass ply to construct the current tire carcass, which consists of two tire carcass plies.

[0010] If the number of carcass plies that make up the tire carcass is reduced, the strength of the tire carcass will decrease. In order to achieve tire weight reduction while suppressing the reduction in strength, research is being conducted on using thicker cords than those used in the past, specifically, using large-diameter cords with a total fineness of 6,000 to 9,000 dtex as carcass cords.

[0011] During the vulcanization process, the spacing between the tire carcass cords tends to widen at the boundary between the tread and sidewall portions (hereinafter referred to as the buttress portion).

[0012] In a carcass composed of a single carcass ply, unlike a carcass composed of two carcass ply, the carcass ply layers are not mutually constrained. The spacing between the carcass ply lines in the buttress section is prone to widening, raising concerns about ply unraveling in that section.

[0013] In order to achieve weight reduction while suppressing the decrease in tire body strength, it is necessary to establish a technology that can suppress the formation of open lines.

[0014] This invention was made in view of the following circumstances. The object of this invention is to provide a tire that can achieve lightweighting while suppressing the reduction of tire carcass strength without compromising appearance quality.

[0015] Technical solutions for solving technical problems

[0016] One aspect of the present invention relates to a tire comprising: a tread that contacts the road surface; a pair of sidewalls connected to the ends of the tread and located radially inside the tread; a pair of beads located radially inside the sidewalls; a tire carcass located inside the tread and the pair of sidewalls and between a first bead and a second bead of the pair of beads; a belt layer located radially between the tread and the tire carcass; an inner liner located inside the tire carcass; and a separating layer located between the tire carcass and the inner liner. Each bead has a core and a triangular rubber located radially outside the core. The tire carcass is composed of a tire carcass ply. The tire carcass ply has: a layer body that is positioned between the core of the first bead and the core of the second bead; and a pair of fold-back portions connected to the layer body and folded back at the core. The tire carcass ply is composed of a plurality of parallel tire carcass cords and adhesive rubber covering these tire carcass cords. The total fineness of the carcass cords is between 6000 dtex and 9000 dtex. The separator layer is located between the first bead and the second bead. The ratio of the thickness of the adhesive rubber located between the separator layer and the carcass cords to the thickness of the separator layer is between 0.2 and 0.6.

[0017] Preferably, in this tire, the inner liner is composed of an inner layer constituting the inner surface of the tire and an outer layer laminated on the outside of the inner layer. The inner layer is a crosslinked rubber composition comprising butyl rubber. The outer layer is a crosslinked rubber composition comprising natural rubber. The ratio of the complex elastic modulus of the insulating layer to the complex elastic modulus of the outer layer is 1.0 or more and 2.0 or less.

[0018] Preferably, in this tire, the end of the separator layer is located radially outside the outer end of the triangular rubber. The ratio of the radial distance from the end of the separator layer to the outer end of the triangular rubber to the tire section height is 0.15 to 0.35.

[0019] Preferably, in this tire, the end of the fold-back portion is located radially inside the end of the insulating layer. The ratio of the radial distance from the end of the insulating layer to the end of the fold-back portion to the radial distance from the end of the insulating layer to the outer end of the triangular rubber is 1.2 or more and 2.0 or less.

[0020] Preferably, in this tire, the separator layer is composed of a pair of rubber layers separated axially from each other on the equatorial plane. The outer ends of the rubber layers are located axially inside the ends of the belt layer. The axial distance from the outer ends of the rubber layers to the ends of the belt layer is 10 mm to 50 mm.

[0021] Preferably, in this tire, the ratio of the distance between the carcass cords in the carcass ply to the outer diameter of the carcass cord is 0.15 to 0.45.

[0022] Preferably, in this tire, a plurality of recesses arranged circumferentially are provided on the outer surface of the tire. The shortest distance from each recess to the end of the folded portion is more than 2 mm and less than 10 mm.

[0023] The effects of the invention

[0024] According to the present invention, it is possible to obtain a tire that can achieve lightweighting while suppressing the reduction of tire body strength without compromising appearance quality. Attached Figure Description

[0025] Figure 1 This is a cross-sectional view showing a portion of a tire according to the first embodiment of the present invention.

[0026] Figure 2 It is along Figure 1 A cross-sectional view of line II-II.

[0027] Figure 3 It means Figure 1 A cross-sectional view of a portion of the tire shown.

[0028] Figure 4 It means Figure 1 A cross-sectional view of a portion of the tire shown.

[0029] Figure 5 It means Figure 1 A cross-sectional view of the first modified example of the tire shown.

[0030] Figure 6 It means Figure 4 The image shows a cross-sectional view of a portion of the sidewall of a tire.

[0031] Figure 7 It is along Figure 6 A cross-sectional view of line VII-VII.

[0032] Figure 8 It means Figure 1 A cross-sectional view of a second modified example of the tire shown.

[0033] Figure 9 It means Figure 8A cross-sectional view of a modified tire shown.

[0034] Figure 10 This is a cross-sectional view showing a portion of a tire according to the second embodiment of the present invention.

[0035] Symbol Explanation

[0036] Tires 2, 2a, 2b, 2c, 72…

[0037] 4…tread

[0038] 6…sidewall

[0039] 10, 74... tire bead

[0040] 12… fetus

[0041] 14… Belt layer

[0042] 20…inner lining

[0043] 22…Isolation layer

[0044] 38, 76...core

[0045] 40, 78... Triangle rubber

[0046] 42…Carcass ply

[0047] 42a… Main body

[0048] 42b… Turnaround section

[0049] 44…Pelvic cord

[0050] 46… Adhesive rubber

[0051] 56…Inner layer

[0052] 58…outer layer

[0053] 60… rubber layer

[0054] 62, 62a…recessed portion

[0055] 80…First Triangle Rubber

[0056] 82…Second Triangle Glue Detailed Implementation

[0057] Hereinafter, the present invention will be described in detail with appropriate reference to the accompanying drawings and according to preferred embodiments.

[0058] The tire is assembled onto a rim. The tire is filled with air, and the internal pressure of the tire can be adjusted. In this invention, the tire assembled onto the rim is a tire-rim assembly. The tire-rim assembly comprises a rim and a tire assembled onto the rim.

[0059] In this invention, the tire is assembled to a standard rim and the tire's internal pressure is adjusted to a standard internal pressure. The state in which no load is applied to the tire is called the standard state.

[0060] In this invention, unless otherwise specified, the dimensions and angles of various parts of the tire are measured under standard conditions.

[0061] The dimensions and angles of various parts of the tire's radial section, which cannot be measured with the tire assembled on a standard rim, are measured in a tire section (hereinafter referred to as the reference section) obtained by cutting the tire along a plane containing the axis of rotation. In this measurement, the distance between the left and right bead sections is set to be consistent with the distance between the bead sections of a tire assembled on a standard rim.

[0062] A standard rim refers to the rim specified in the tire's specifications. The "standard rim" in JATMA specifications, the "Design Rim" in TRA specifications, and the "Measuring Rim" in ETRTO specifications are all standard rims.

[0063] Standard internal pressure refers to the internal pressure specified in the tire's specifications. The "maximum pressure" in JATMA specifications, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSUREES" in TRA specifications, and "INFLATION PRESSURE" in ETRTO specifications are all standard internal pressures.

[0064] Standard load capacity refers to the load capacity specified in the tire's specifications. The "maximum load capacity" in JATMA specifications, the "maximum value" listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSUREES" in TRA specifications, and "LOAD CAPACITY" in ETRTO specifications are all standard load capacities.

[0065] In this invention, the rubber composition is a composition comprising an uncrosslinked base rubber obtained by mixing the base rubber and a pharmaceutical agent in a mixing mill such as a Banbury mixer. Crosslinked rubber is a crosslinked product of a rubber composition obtained by pressurizing and heating the rubber composition. Crosslinked rubber includes crosslinked products of the base rubber. Crosslinked rubber is also called vulcanized rubber, and the rubber composition is also called unvulcanized rubber.

[0066] Examples of base rubbers include natural rubber (NR), butadiene rubber (BR), styrene-butadiene rubber (SBR), isoprene rubber (IR), ethylene propylene rubber (EPDM), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), and butyl rubber (IIR). Examples of pharmaceuticals include reinforcing agents such as carbon black and silica, plasticizers such as aromatic essential oils, fillers such as zinc oxide, lubricants such as stearic acid, anti-aging agents, processing aids, sulfur, and vulcanization accelerators. The selection of the base rubber and pharmaceuticals, as well as the content of the selected pharmaceuticals, are appropriately determined based on the specifications of various factors applicable to the rubber composition, such as the tread and sidewall.

[0067] In this invention, the complex elastic modulus of the component constituting the tire, which is made of cross-linked rubber, is measured using a viscoelastic spectrometer (VES manufactured by Iwamoto Manufacturing Co., Ltd.) under the following conditions, according to JIS K6394. The complex elastic modulus in this invention is the complex elastic modulus at 70°C.

[0068] Initial strain = 10%

[0069] Dynamic strain = 2%

[0070] Frequency = 10Hz

[0071] Deformation mode = stretching

[0072] Temperature = 70℃

[0073] In this measurement, the test piece is sampled from the tire. In cases where it is not possible to sample the test piece from the tire, the test piece is sampled from a sheet of cross-linked rubber (hereinafter also referred to as rubber sheet) obtained by pressurizing and heating the rubber composition used to form the component of the test object at a temperature of 170°C for 12 minutes.

[0074] In this invention, the structure (cord construction) of a cord made of organic fibers is represented according to JIS L 1017, "5.2 Method of representing cord structure". When the cord is, for example, made of two monofilaments (filaments) twisted together with a fineness of 1400 dtex, the cord structure is represented by 1400 dtex / 2. The total fineness (dtex) of the cord is represented by the product of the fineness of the monofilament (1400 dtex) and the number of monofilaments (2) (1400 × 2 = 2800).

[0075] In this invention, the tread portion of the tire is the part of the tire that contacts the road surface. The bead portion is the part of the tire that fits into the rim. The sidewall portion is the part of the tire that is positioned between the tread portion and the bead portion. The tire's components include the tread portion, a pair of bead portions, and a pair of sidewall portions. The boundary between the tread portion and the sidewall portion is also referred to as the buttress portion.

[0076] [First Implementation Method]

[0077] Figure 1 This represents a portion of the tire 2 according to the first embodiment of the present invention. The tire 2 is a pneumatic tire for passenger cars.

[0078] Figure 1 This represents a portion of a cross-section (hereinafter referred to as the meridian section) of tire 2 along a plane containing the axis of rotation of tire 2. Figure 1 In the diagram, the left-right direction represents the axial direction of tire 2, and the up-down direction represents the radial direction of tire 2. (And...) Figure 1 The direction perpendicular to the paper is the circumference of tire 2. The single-dotted line CL represents the equatorial plane of tire 2.

[0079] exist Figure 1 In this configuration, tire 2 is mounted on rim R (standard rim). Tire 2 is filled with air, and its internal pressure can be adjusted.

[0080] exist Figure 1 In the diagram, the axially extending solid line BBL is the bead baseline. This bead baseline BBL is the line that specifies the rim diameter R of the rim (refer to JATMA, etc.).

[0081] exist Figure 1 The location represented by the symbol PC is the intersection of the outer surface of tire 2 and the equatorial plane CL. The intersection point PC is the equator of tire 2. When the groove is located on the equatorial plane CL, the equator PC is specified based on a virtual outer surface obtained assuming there is no groove. The equator PC is the radial outer end of tire 2.

[0082] exist Figure 1 In this context, the length represented by the symbol HS is the section height of tire 2 (see JATMA et al.). The section height HS (also known as tire section height HS) is the radial distance from the bead baseline BBL to the equator PC.

[0083] exist Figure 1 In this context, the position indicated by the symbol PW is the axial outer end of tire 2 (hereinafter referred to as the outer end PW). When the outer surface has decorations such as patterns or text, the outer end PW is specified based on an imaginary outer surface obtained assuming no decoration.

[0084] The axial distance from the first outer end PW to the second outer end PW obtained under standard conditions is the section width of tire 2 (refer to JATMA et al.). The outer end PW is also referred to as the maximum width position.

[0085] exist Figure 1 In the diagram, the position represented by the symbol PT is the toe of tire 2. The toe PT is the boundary between the outer surface (hereinafter also referred to as the outer surface 2G) and the inner surface (hereinafter also referred to as the inner surface 2N) of tire 2.

[0086] exist Figure 1 In this diagram, the symbol PD represents a position on the outer surface 2G of the tire. The symbol HD represents the radial distance from the equator PC to position PD. In this tire 2, the radial distance HD is 0.23 times the tire section height HS. The position represented by the symbol PD is the position where the radial distance HD from the equator PC is 0.23 times the tire section height HS.

[0087] Although not described in detail, a tire is obtained by pressurizing and heating a green tire within a mold. When the mold is a combination mold, it includes: a tread ring forming the tread portion, a pair of side plates forming the sidewall portion, and a pair of bead rings forming the bead portion. The tread ring is composed of multiple combination molds arranged circumferentially.

[0088] The aforementioned position PD is the position on the outer surface 2G of the tire, corresponding to the boundary position of the combined mold and the side plate on the mold cavity surface of the mold (not shown) of the tire 2.

[0089] In this invention, the position PD is also referred to as the position corresponding to the buttress boundary.

[0090] Figure 2 It indicates along Figure 1 A cross-section of tire 2 (specifically, the sidewall) along the II-II line. Figure 2 On the paper, the right side is the outer surface of the tire, side 2G, and the left side is the inner surface of the tire, side 2N.

[0091] exist Figure 1 In the middle, line II-II is the normal line to the inner surface 2N of the tire at position PD corresponding to the buttress boundary. Figure 2 This represents a cross-section of the tire sidewall near the PD location corresponding to the buttress boundary.

[0092] The tire 2 has a tread 4, a pair of sidewalls 6, a pair of overlapping portions 8, a pair of bead 10, a carcass 12, a belt layer 14, a belt 16, a pair of bead wraps 18, an inner liner 20, and a separator layer 22.

[0093] The tread 4 is in contact with the road surface on the tread surface 24. The tread 4 has a tread surface 24 that is in contact with the road surface. Grooves 26 are etched on the tread 4.

[0094] The tread surface 24 is part of the tire outer surface 2G. The tread surface 24 is connected to the tire sidewall 28. The tire outer surface 2G has the tread surface 24 and a pair of tire sidewalls 28.

[0095] The tread 4 has a tread body 30 and a pair of wing portions 32.

[0096] Each wing portion 32 is located on the axially outer side of the tread body 30. The wing portion 32 joins the tread body 30 and the sidewall 6. The wing portion 32 is made of cross-linked rubber with adhesive properties taken into account.

[0097] The tread body 30 has a crown portion 34 and a base portion 36. The crown portion 34 includes a tread surface 24. The crown portion 34 is in contact with the road surface. The crown portion 34 is made of cross-linked rubber that takes into account abrasion resistance and grip performance. The base portion 36 is located radially inside the crown portion 34. The entire base portion 36 is covered by the crown portion 34. The base portion 36 is made of cross-linked rubber with low heat generation.

[0098] Each sidewall 6 is connected to the end of the tread 4. The sidewall 6 is located radially inside the tread 4. The sidewall 6 is made of cross-linked rubber with cut resistance taken into account.

[0099] Each overlapping portion 8 is located radially inside the sidewall 6. The outer end 8e of the overlapping portion 8 is located radially inside the maximum width position PW. The overlapping portion 8 contacts the rim R. The overlapping portion 8 is made of cross-linked rubber with wear resistance in mind.

[0100] exist Figure 1 The position indicated by the symbol PS is the position on the outer surface 2G of the tire, corresponding to the radial outer end of the contact surface between the tire 2 and the rim R. Position PS is also referred to as the outer end position of the contact surface.

[0101] Each bead 10 is located axially inside the overlap 8. The bead 10 is located radially inside the sidewall 6.

[0102] The bead 10 has a core 38 and a triangular rubber 40. The core 38 extends circumferentially. Although not shown, the core 38 includes a metal wire made of steel wire. The triangular rubber 40 is located radially outward of the core 38. The triangular rubber 40 gradually tapers radially outward. The triangular rubber 40 is made of cross-linked rubber with high rigidity. The length of the triangular rubber 40 is preferably 25 mm to 45 mm. The length of the triangular rubber 40 is represented by the length of the line segment connecting the center in the width direction of the bottom surface of the triangular rubber 40 and its outer end 40e.

[0103] The outer end 40e of the triangular rubber 40 is located radially inside the maximum width position PW. The outer end 40e of the triangular rubber 40 is the outer end 10e of the bead 10. The bead 10 as a whole is located radially inside the maximum width position PW.

[0104] exist Figure 1 In the diagram, the length represented by the symbol HA is the radial distance from the bead baseline BBL to the outer end 40e of the triangular rubber 40.

[0105] In this tire 2, the ratio of radial distance HA to tire section height HS (HA / HS) is 0.20 or more and 0.30 or less.

[0106] The tire body 12 is located inside the tread 4, a pair of sidewalls 6, and a pair of overlaps 8. The tire body 12 is positioned between the first bead 10 and the second bead 10 of a pair of bead 10.

[0107] The carcass of passenger car tires typically consists of two carcass plies. The carcass 12 of this tire 2 consists of one carcass ply 42. The carcass 12 contributes to the lightweight design of the tire 2.

[0108] The carcass ply 42 includes a ply body 42a and a pair of first fold-back portions 42b. The ply body 42a is positioned between the core 38 of the first bead 10 and the core 38 of the second bead 10. Each fold-back portion 42b is connected to the ply body 42a and folds back from the axial inside to the outside at each core 38.

[0109] Figure 1 The length represented by the symbol HF is the radial distance from the bead baseline BBL to the end 42be of the turnaround section 42b. The radial distance HF is also called the turnaround section height.

[0110] In this tire 2, the ratio of the foldback height HF to the tire profile height HS (HF / HS) is 0.10 or more and 0.20 or less.

[0111] like Figure 2 As shown, the carcass ply 42 comprises a plurality of carcass cords 44 arranged side by side. These carcass cords 44 are covered by adhesive rubber 46. The carcass ply 42 is composed of a plurality of carcass cords 44 and adhesive rubber 46.

[0112] The tire carcass cord 44 of this tire 2 is a cord made of organic fibers (hereinafter referred to as organic fiber cord). Although not shown, the carcass cord 44 is formed by twisting together multiple filaments made of organic fibers. Examples of organic fibers include nylon fibers, synthetic fibers, polyester fibers, and aramid fibers. Examples of polyester fibers include polyethylene terephthalate fibers and polyethylene naphthalate fibers. In this tire 2, polyethylene terephthalate fibers are preferred as organic fibers.

[0113] exist Figure 2 In this tire 2, the length represented by the symbol GD is the outer diameter of the carcass cord 44. The outer diameter GD of the carcass cord 44 is controlled by the total fineness described later. The outer diameter GD is preferably 0.85 mm to 1.05 mm. In this invention, the outer diameter GD is represented by the "cord gauge" specified in JIS L 1017.

[0114] Although not shown in the diagram, the carcass cords 44 intersect the equatorial plane CL. The angle between the carcass cords 44 and the equatorial plane CL, i.e., the intersection angle, is between 70° and 90°. The carcass 12 of this tire 2 has a radial structure. On the sidewall, the carcass cords 44 extend in a generally radial direction.

[0115] The carcass ply 42 is formed using a ply material (not shown). Although not described in detail, the ply material is obtained by covering both sides of a fabric-like structure, woven from carcass cords 44 (as warp) and weft threads intersecting the warp, with adhesive rubber 46. In the ply material, the carcass cords 44 are configured such that their cross-sectional center is located at the center of the ply material's thickness direction.

[0116] exist Figure 2 In this text, the length represented by the symbol tc is the thickness of the carcass ply 42. Considering the influence of the carcass 12 on strength and mass, the thickness tc of the carcass ply 42 is set. In this tire 2, the thickness tc of the carcass ply 42 is preferably 1.1 mm or more and 1.4 mm or less.

[0117] In this invention, the outer portion of the carcass 12 refers to the portion extending from the outer surface of the carcass 12 to the outer surface 2G of the tire. The thickness of the outer portion of the carcass 12 is represented by the distance from the outer surface of the carcass 12 to the outer surface 2G of the tire. This distance is measured along the normal to the outer surface of the carcass 12. Specifically, in this tire 2, this distance is measured along the normal to the ply body 42a.

[0118] exist Figure 1 The position denoted by the symbol PF is located radially inward from the maximum width position PW, representing the outer portion of the tire carcass 12 and indicating the maximum thickness. In this invention, this position PF is a reference position.

[0119] In this tire 2, the reference position PF is located radially between the maximum width position PW and the rim R.

[0120] The belt layer 14 is located radially inside the tread 4. The belt layer 14 is stacked on the carcass 12. The belt layer 14 is located radially between the tread 4 and the carcass 12. The aforementioned equatorial plane CL intersects the belt layer 14 at the center of its axial width.

[0121] In this tire 2, the axial width of the belt layer 14 is more than 70% and less than 85% of the cross-sectional width of the tire 2.

[0122] The belt layer 14 includes a first layer 48 and a second layer 50. The first layer 48 is located radially outside the layer body 42a and is stacked on the layer body 42a. The second layer 50 is located radially outside the first layer 48 and is stacked on the first layer 48.

[0123] like Figure 1As shown, the end of the second layer 50 is located axially inside the end of the first layer 48. The second layer 50 is narrower than the first layer 48. The length from the end of the second layer 50 to the end of the first layer 48 is more than 3 mm and less than 10 mm. The axial width of the aforementioned belt layer 14 is expressed using the axial width of the wide first layer 48.

[0124] Although not illustrated, the first layer 48 and the second layer 50 each comprise multiple parallel belt-layer cords. These belt-layer cords are covered with adhesive rubber. Each belt-layer cord is inclined relative to the equatorial plane CL. The belt-layer cords are made of steel.

[0125] The belt 16 is located radially between the tread 4 and the belt layer 14. The belt 16 is stacked on the belt layer 14.

[0126] The end 16e of the strap 16 is located axially outside the end 14e of the strap layer 14. The length from the end 14e of the strap layer 14 to the end 16e of the strap 16 is more than 3 mm and less than 7 mm.

[0127] Although not shown, the strap 16 comprises a spirally wound strap cord. The strap cord is covered with adhesive rubber. The strap cord extends substantially circumferentially. Specifically, the angle between the strap cord and the circumferential direction is less than 5°. The strap 16 has a seamless structure.

[0128] The belt cord is an organic fiber cord. Examples of organic fibers include nylon, synthetic fibers, polyester, and aramid fibers.

[0129] The strap 16 includes a full strap 52 and a pair of side straps 54.

[0130] The full-strand tape 52 is stacked on the belt layer 14. The full-strand tape 52 covers the entire belt layer 14. Each end 52e of the full-strand tape 52 is located axially outside the end 14e of the belt layer 14.

[0131] A pair of sidebands 54 are separated along the equatorial plane CL and arranged axially. Each sideband 54 is stacked on the full bundle 52. The sidebands 54 cover portions of the ends 52e of the full bundle 52.

[0132] From a lightweight perspective, the strap 16 can also consist of only the full strap 52. Alternatively, the strap 16 can consist of only a pair of side straps 54.

[0133] Each bead wrap 18 is located radially inside the bead 10. The bead wrap 18 contacts the rim R. In this tire 2, the bead wrap 18 is composed of cloth and rubber impregnated in the cloth.

[0134] like Figure 1As shown, the inner end 18ue of the bead wrap 18 forms part of the inner surface 2N of the tire. The outer end 18se of the bead wrap 18 is further radially outward than the inner end 18ue. The outer end 18se of the bead wrap 18 is located between the bead 10 and the overlap 8.

[0135] The inner liner 20 is located inside the tire carcass 12. The inner liner 20 maintains the internal pressure of the tire 2.

[0136] like Figure 2 As shown, the inner liner 20 consists of two layers: an inner layer 56 and an outer layer 58. The inner layer 56 forms the inner surface 2N of the tire. The outer layer 58 is stacked on the outside of the inner layer 56. The outer layer 58 is located between the inner layer 56 and the tire carcass 12.

[0137] The thickness of the inner layer 56 is 0.3 mm to 0.8 mm. The thickness of the outer layer 58 is 0.3 mm to 0.8 mm.

[0138] The inner layer 56 is a crosslinked rubber composition. The rubber composition used for the inner layer 56 (hereinafter referred to as the first rubber composition) contains butyl rubber as the base rubber. The main component of the base rubber of the first rubber composition is butyl rubber. The inner layer 56 is composed of a crosslinked rubber with excellent air barrier properties.

[0139] Examples of butyl rubbers include butyl rubber and halogenated butyl rubber. Examples of halogenated butyl rubbers include chlorobutyl rubber and bromobutyl rubber.

[0140] In this invention, the main component of the base rubber is butyl rubber, which means that the amount of butyl rubber contained in the base rubber is more than 50% by mass of the total amount of the base rubber.

[0141] From the viewpoint of forming an inner layer 56 with good air shielding properties, the amount of butyl rubber contained in the base material rubber is preferably 70% or more by mass of the total amount of base material rubber, more preferably 90% or more by mass, and even more preferably 95% or more by mass. The base material rubber is particularly preferably butyl rubber.

[0142] In this tire 2, the rubber composition typically used for the inner layer 56 of the inner liner 20 is used as the first rubber composition.

[0143] The outer layer 58 is a crosslinked rubber composition. The rubber composition used for the outer layer 58 (hereinafter referred to as the second rubber composition) contains natural rubber as the base rubber. The main component of the base rubber of the second rubber composition is natural rubber. The second rubber composition is a rubber composition designed with consideration for adhesion to the tire carcass 12, the separator layer 22, and the inner layer 56. In this tire 2, the inner layer 56 is bonded to the tire carcass 12 and the separator layer 22 via the outer layer 58. The base rubber of the second rubber composition does not contain butyl rubber.

[0144] In this invention, the main component of the base rubber is natural rubber, which means that the amount of natural rubber contained in the base rubber is more than 50% by mass of the total amount of base rubber.

[0145] From the viewpoint of forming an outer layer 58 with good adhesion, the amount of natural rubber contained in the base material rubber is preferably 70% or more by mass of the total amount of base material rubber, more preferably 90% or more by mass, and even more preferably 95% or more by mass.

[0146] In this tire 2, the rubber composition typically used for the outer layer 58 of the inner liner 20 is used as the second rubber composition.

[0147] In this tire 2, the complex elastic modulus E*t of the outer layer 58 is above 3.0 MPa and below 5.0 MPa.

[0148] The isolation layer 22 is located between the tire body 12 and the inner liner 20.

[0149] The end 22e of the isolation layer 22 is located radially inside the maximum width position PW. The position of the end 22e of the isolation layer 22 can coincide with the radial maximum width position PW. The end 22e of the isolation layer 22 can also be located radially outside the maximum width position PW.

[0150] The isolation layer 22 is located between the tire body 12 and the inner liner 20 and between the first bead 10 and the second bead 10.

[0151] As described above, the carcass ply 42 of the tire 2 comprises a plurality of carcass cords 44 arranged side by side. Figure 2 As shown, multiple tire cords 44 are spaced apart.

[0152] Near the corresponding position PD at the buttress boundary, the isolation layer 22 is stacked on the outer layer 58 of the inner liner layer 20. The carcass ply 42 is stacked on the isolation layer 22. The isolation layer 22 and the adhesive rubber 46 covering the carcass ply 44 are located between the outer layer 58 and the carcass ply 44.

[0153] exist Figure 2In this context, the length represented by the symbol td is the thickness of the separator layer 22. The length represented by the symbol ta is the thickness of the adhesive rubber 46 located between the separator layer 22 and the carcass cord 44.

[0154] The thickness td of the isolation layer 22 and the thickness ta of the adhesive rubber 46 are measured along the normal of the inner surface 2N of the tire passing through the corresponding position PD of the buttress boundary.

[0155] As described above, in this tire 2, from the point of view of lightweighting, the tire carcass 12 is composed of a single tire carcass ply 42.

[0156] In existing tires, the carcass consists of two carcass plies. In this tire 2, the number of carcass plies 42 constituting the carcass 12 is reduced compared to conventional tires. There are concerns about a decrease in the strength of the carcass 12.

[0157] In this tire 2, the carcass cord 44 uses cords that are thicker than conventional cords. Specifically, cords with a total fineness in the range of 6000 to 9000 dtex are used as the carcass cord 44. The total fineness of the carcass cord 44 in this tire 2 is more than 6000 dtex and less than 9000 dtex.

[0158] The total fineness of the carcass cords 44 is over 6000 dtex, so that although the carcass 12 is composed of a single carcass cord layer 42, the carcass 12 still has the necessary strength. In other words, it prevents the reduction of the strength of the carcass 12.

[0159] The total fineness of the carcass cords 44 is less than 9000 dtex, thus suppressing the impact of the carcass cords 44 on tire weight. The carcass ply 42 containing these carcass cords 44 contributes to the weight reduction of the tire 2.

[0160] In this tire 2, the carcass cord 44 is thicker than the existing carcass cord, and the carcass 12 is composed of a single carcass ply 42.

[0161] During the vulcanization process, the spacing of the carcass cords 44 widens in the sidewall portion, raising concerns that the outer layer 58 of the inner liner 20 may merge between the carcass cords 44. In this case, cord breakage occurs, leading to a decrease in tire appearance quality.

[0162] As described above, in this tire 2, the separator layer 22 is located between the carcass 12 and the inner liner layer 20, and between the first bead 10 and the second bead 10. Specifically, in this tire 2, in the buttress portion where the spacing of the carcass cords 44 is widened, the ratio (ta / td) of the thickness ta of the adhesive rubber 46 located between the separator layer 22 and the carcass cords 44 to the thickness td of the separator layer 22 is 0.2 or more and 0.6 or less.

[0163] Since the ratio (ta / td) is above 0.2, the influence of the separator layer 22 on the mass can be suppressed. In this tire 2, the tire carcass 12, which is composed of a single carcass ply 42, can effectively contribute to weight reduction.

[0164] Because the ratio (ta / td) is below 0.6, the separator layer 22 inhibits the merging of the outer layer 58 into the carcass cords 44. The separator layer 22 helps to suppress the occurrence of open cords. Good appearance quality can be obtained in this tire 2.

[0165] In this tire 2, the appearance quality can be maintained, and lightweighting can be achieved while suppressing the reduction in the strength of the tire body 12.

[0166] In existing tires without a separating layer 22, when coarse cords are used as carcass cords, adjustments are needed to suppress the occurrence of open threads, for example, in fabrics where the carcass cords are warp yarns, such as reducing the restraint of the weft yarns.

[0167] In contrast, in this tire 2, although thick cords are used as the carcass cords 44, there is no need to adjust the weft yarns, etc. In other words, in this tire 2, there is no need to set up special processes to obtain a carcass 12 that contributes to weight reduction. The carcass 12 is formed in the same way as conventional tires that do not require adjustment of the weft yarns, etc.

[0168] In this tire 2, there is no increase in production costs and no damage to appearance quality, achieving lightweighting while suppressing the reduction in the strength of the tire body 12.

[0169] As described above, in this tire 2, the ratio (ta / td) of the thickness ta of the adhesive rubber 46 located between the separator layer 22 and the carcass cord 44 to the thickness td of the separator layer 22 is 0.2 or more and 0.6 or less.

[0170] From the viewpoint of obtaining a tire 2 that can achieve lightweighting while suppressing the reduction of the strength of the tire carcass 12 without compromising appearance quality, the ratio (ta / td) is preferably 0.3 or more, and preferably 0.5 or less.

[0171] In this tire 2, the ratio (E*r / E*t) of the complex elastic modulus E*r of the separator layer 22 to the complex elastic modulus E*t of the outer layer 58 is preferably 1.0 or more and 2.0 or less.

[0172] By setting the ratio (E*r / E*t) to 1.0 or higher, the insertion of the separator layer 22 into the carcass cords 44 of the outer layer 58 is suppressed. In this tire 2, the occurrence of cord breakage can be effectively suppressed. From this point of view, the ratio (E*r / E*t) is more preferably 1.3 or higher, and even more preferably 1.5 or higher.

[0173] By setting the ratio (E*r / E*t) to 2.0 or less, the heat generation of the insulating layer 22 itself can be suppressed. Low rolling resistance is maintained in the tire 2. From this point of view, the ratio (E*r / E*t) is more preferably 1.8 or less, and even more preferably 1.6 or less.

[0174] In this tire 2, the thickness td of the separator layer 22 is preferably 0.2 mm or more and 0.8 mm or less.

[0175] By setting the thickness td to 0.2 mm or more, the separator layer 22 can effectively suppress the intrusion of the outer layer 58 into the carcass cords 44. In this tire 2, the occurrence of cord breakage is more effectively suppressed. From this point of view, the thickness td is more preferably 0.3 mm or more, and even more preferably 0.4 mm or more.

[0176] By setting the thickness td to 0.8 mm or less, the impact of the separator layer 22 on the weight can be suppressed. This separator layer 22 contributes to the weight reduction of the tire 2. From this point of view, the thickness td is more preferably 0.7 mm or less, and even more preferably 0.6 mm or less.

[0177] exist Figure 2 The length represented by the symbol D is the distance between the carcass cords 44 in the carcass ply 42. As described above, in this tire 2, cords with a total fineness in the range of 6000 to 9000 dtex are used as the carcass cords 44.

[0178] In this tire 2, the ratio (D / GD) between the distance D between the carcass cords 44 of the carcass ply 42 and the outer diameter GD of the carcass cords 44 is preferably 0.15 or more and 0.45 or less.

[0179] By setting the ratio (D / GD) to 0.15 or higher, the tire carcass 12 can effectively contribute to the weight reduction of the tire 2. From this point of view, a ratio (D / GD) of 0.20 or higher is more preferable.

[0180] By setting the ratio (D / GD) to 0.45 or less, the strength of the tire carcass 12 can be adequately maintained. From this point of view, the ratio (D / GD) is more preferably 0.40 or less.

[0181] Figure 3 express Figure 1 A portion of the cross-section of tire 2 shown. Figure 3 This refers to the portion from the end of the tread area to the bead area.

[0182] The end 22e of the isolation layer 22 is located radially outside the outer end 40e of the triangular adhesive 40.

[0183] The triangular rubber 40 is laminated on the carcass ply 42 on the radially inner portion of the outer end 40e of the triangular rubber 40. As described above, the triangular rubber 40 is made of cross-linked rubber with high rigidity. In this tire 2, the triangular rubber 40 restricts the movement of the carcass ply 44 caused by shape changes during the vulcanization process. In this tire 2, even if the separator layer 22 is not provided on the radially inner sidewall portion of the outer end 40e of the triangular rubber 40, it is difficult for the ply to break. By positioning the end 22e of the separator layer 22 on the radially outer sidewall of the outer end 40e of the triangular rubber 40, the influence of the separator layer 22 on the quality of the tire 2 can be effectively suppressed. This tire 2 can achieve lightweight while maintaining good appearance quality. From this point of view, the end 22e of the separator layer 22 is preferably located on the radially outer sidewall of the outer end 40e of the triangular rubber 40.

[0184] exist Figure 3 The length represented by the symbol Hc is the radial distance from the end 22e of the insulating layer 22 to the outer end 40e of the triangular adhesive 40. In this invention, when the end 22e of the insulating layer 22 is located radially outside the outer end 40e of the triangular adhesive 40, the radial distance Hc is represented by a positive number.

[0185] In this tire 2, the ratio of radial distance Hc to tire section height HS (Hc / HS) is preferably 0.15 or more and 0.35 or less.

[0186] By setting the ratio (Hc / HS) to 0.15 or higher, the impact of the separator layer 22 on the mass is effectively suppressed. The separator layer 22 contributes to the weight reduction of the tire 2. From this point of view, the ratio (Hc / HS) is more preferably 0.20 or higher.

[0187] By setting the ratio (Hc / HS) to 0.35 or less, the separator layer 22 can effectively help suppress the occurrence of open lines in the buttress. This maintains good appearance quality in the tire 2. From this perspective, a ratio (Hc / HS) of 0.30 or less is more preferable.

[0188] In this tire 2, the end 42be of the fold-back portion 42b is located radially outward of the core 38. The end 42be of the fold-back portion 42b is located radially inward of the maximum width position PW. The tire carcass 12 of this tire 2 has a low turn-up structure. For example, as... Figure 3 As shown, the end 42be of the folded-back portion 42b of the tire 2 is located radially inward of the outer end 40e of the triangular rubber 40. The tire carcass 12 having this folded-back portion 42b can contribute to the weight reduction of the tire 2. From this point of view, the end 42be of the folded-back portion 42b is preferably located radially inward of the outer end 40e of the triangular rubber 40.

[0189] exist Figure 3In this tire 2, the symbol PR indicates the radially outer end of the rim R. The end 42be of the folded-back portion 42b is located radially inner to the outer end PR of the rim R. This helps to suppress the concentration of deformation at the end 42be of the folded-back portion 42b. In this tire 2, good durability is maintained while achieving lightweight design. From this perspective, the end 42be of the folded-back portion 42b is more preferably located radially inner to the outer end PR of the rim R.

[0190] like Figure 3 As shown, in this tire 2, the outer end 40e of the triangular rubber 40 is located radially inside the end 22e of the insulating layer 22, and the end 42be of the folded-back portion 42b is located radially inside the outer end 40e of the triangular rubber 40.

[0191] In this tire 2, the end 42be of the foldback portion 42b is located radially inside the end 22e of the isolation layer 22.

[0192] exist Figure 3 The length represented by the symbol Hf is the radial distance from the end 22e of the isolation layer 22 to the end 42be of the foldback portion 42b.

[0193] In this tire 2, the ratio (Hf / Hc) of the radial distance Hf to the radial distance Hc from the end 22e of the separator layer 22 to the outer end 40e of the triangular rubber 40 is preferably 1.2 or more and 2.0 or less.

[0194] By setting the ratio (Hf / Hc) to 1.2 or higher, the isolation layer 22 can effectively help suppress the occurrence of open lines in the buttress portion. In this tire 2, good appearance quality is maintained. From this viewpoint, the ratio (Hf / Hc) is more preferably 1.3 or higher, and even more preferably 1.4 or higher.

[0195] By setting the ratio (Hf / Hc) to 2.0 or less, the influence of the separator layer 22 on the mass can be effectively suppressed. The separator layer 22 contributes to the weight reduction of the tire 2. From this point of view, the ratio (Hf / Hc) is more preferably 1.8 or less, and even more preferably 1.6 or less.

[0196] like Figure 1 As shown, the insulating layer 22 of the tire 2 is composed of a pair of rubber layers 60. The pair of rubber layers 60 are separated along the axial direction by the equatorial plane CL.

[0197] The inner end 60ue of the rubber layer 60 is the end 22e of the isolation layer 22. The inner end 60ue of the rubber layer 60 is located radially outside the outer end 40e of the triangular rubber 40.

[0198] On the radially inner side of the inner end 60ue of the rubber layer 60, the outer layer 58 of the inner liner 20 is bonded to the carcass ply 42. In the portion from the inner end 60ue to the outer end 60se of the rubber layer 60, the outer layer 58 is bonded to the carcass ply 42 via the rubber layer 60. In the portion between the outer end 60se of the first rubber layer 60 and the outer end 60se of the second rubber layer 60 (not shown), the outer layer 58 is bonded to the carcass ply 42.

[0199] The tire 2 does not have a third rubber layer 60 between the first rubber layer 60 and the second rubber layer 60. The absence of a third rubber layer 60 between the first rubber layer 60 and the second rubber layer 60 in the separator layer 22 contributes to the weight reduction of the tire 2. From this point of view, the separator layer 22 is preferably composed of a pair of rubber layers 60 separated by the equatorial plane CL and arranged axially.

[0200] In the region from the outer end 60se of the first rubber layer 60 to the outer end 60se of the second rubber layer 60, the belt layer 14 is located radially outward of the tire carcass 12. This belt layer 14 restricts the movement of the carcass cords 44 caused by shape changes during the vulcanization process. In this tire 2, even without a rubber layer 60 between the first and second rubber layers 60, cord breakage is unlikely. In this tire 2, lightweight design is achieved while maintaining good appearance quality.

[0201] In this tire 2, the outer end 60se of the rubber layer 60 is located axially inside the end 14e of the belt layer 14. Therefore, even in the tire 2, the rubber layer 60 can effectively suppress the occurrence of open lines in the buttress portion, which is composed of a relatively thin thickness. This tire 2 achieves lightweighting while maintaining good appearance quality. From this viewpoint, the outer end 60se of the rubber layer 60 is preferably located axially inside the end 14e of the belt layer 14.

[0202] Figure 3 The length represented by the symbol Lb is the axial distance from the outer end 60se of the rubber layer 60 to the end 14e of the belt layer 14. In this invention, when the outer end 60se of the rubber layer 60 is located axially inside the end 14e of the belt layer 14, the axial distance Lb is represented by a positive number.

[0203] In this tire 2, the axial distance Lb is preferably 10mm or more and 50mm or less.

[0204] By setting the axial distance Lb to 10 mm or more, the occurrence of open lines in the buttress portion of the rubber layer 60 can be effectively suppressed. Furthermore, since the outer end 60se of the rubber layer 60 is separately configured from the end 14e of the belt layer 14, deformation concentration at the end 14e of the belt layer 14 can be suppressed. In this tire 2, good durability can be maintained. From this viewpoint, the axial distance Lb is more preferably 20 mm or more, and even more preferably 25 mm or more.

[0205] By setting the axial distance Lb to 50 mm or less, the insulating layer 22, consisting of a pair of rubber layers 60, can effectively contribute to weight reduction. From this point of view, the axial distance Lb is more preferably 40 mm or less, and even more preferably 35 mm or less.

[0206] Figure 4 express Figure 1 A portion of the cross-section of tire 2 shown. Figure 4 This refers to the portion from the end of the tread area to the bead area.

[0207] In this tire 2, the outer end 40e of the triangular rubber 40 is located radially inside the outer end 8e of the overlapping portion 8. The outer end 18se of the bead wrap 18 is located radially inside the outer end 40e of the triangular rubber 40. The end 42be of the folded portion 42b is located radially inside the outer end 18se of the bead wrap 18.

[0208] exist Figure 4 In the diagram, the length represented by symbol H2 is the radial distance from the end 42be of the fold-back portion 42b to the outer end 8e of the overlap portion 8. The length represented by symbol H3 is the radial distance from the end 42be of the fold-back portion 42b to the outer end 40e of the triangular rubber 40. The length represented by symbol H4 is the radial distance from the end 42be of the fold-back portion 42b to the outer end 18se of the bead wrap 18.

[0209] In this tire 2, the end 42be of the folded-back portion 42b is located radially inside the outer end 8e of the overlapping portion 8. The end 42be of the folded-back portion 42b is spaced apart from the outer end 8e of the overlapping portion 8. This suppresses damage originating from the interface peeling between the sidewall 6 and the overlapping portion 8, thus maintaining good durability in the tire 2. From this viewpoint, the radial distance H2 from the end 42be of the folded-back portion 42b to the outer end 8e of the overlapping portion 8 is preferably 5 mm or more, more preferably 20 mm or more. From the viewpoint that the folded-back portion 42b is of sufficient length and the carcass ply 42 is stably fixed to the bead 10, the radial distance H2 is preferably 35 mm or less, more preferably 30 mm or less.

[0210] In this tire 2, the end 42be of the folded-back portion 42b is located radially inside the outer end 40e of the triangular rubber 40. The end 42be of the folded-back portion 42b is spaced apart from the outer end 40e of the triangular rubber 40. This suppresses damage originating from interface peeling near the outer end 40e of the triangular rubber 40, thus maintaining good durability in the tire 2. From this viewpoint, the radial distance H3 from the end 42be of the folded-back portion 42b to the outer end 40e of the triangular rubber 40 is preferably 3 mm or more, more preferably 5 mm or more. From the viewpoint that the carcass ply 42 is stably fixed to the bead 10 by constituting a folded-back portion 42b of sufficient length, the radial distance H3 is preferably 25 mm or less, more preferably 20 mm or less.

[0211] In this tire 2, the end 42be of the folded-back portion 42b is located radially inside the outer end 18se of the bead wrap 18. The end 42be of the folded-back portion 42b is spaced apart from the outer end 18se of the bead wrap 18. This helps to suppress damage originating from interface peeling near the outer end 18se of the bead wrap 18, thus maintaining good durability in the tire 2. From this viewpoint, the radial distance H4 from the end 42be of the folded-back portion 42b to the outer end 18se of the bead wrap 18 is preferably 3 mm or more, more preferably 8 mm or more. From the viewpoint that the folded-back portion 42b is of sufficient length and the carcass ply 42 is stably fixed to the bead 10, the radial distance H4 is preferably 20 mm or less, more preferably 15 mm or less.

[0212] Figure 5 express Figure 1 The modified example of tire 2 shown (hereinafter referred to as tire 2a). Figure 5 This represents a portion of the meridian profile of tire 2a.

[0213] exist Figure 5 In the tire 2a shown, the end 42be of the folded-back portion 42b is located radially inside the maximum width position PW. The tire carcass 12 of this tire 2a has a low-profile folding structure.

[0214] The end 42be of the folding-back portion 42b is located radially inside the outer end 40e of the triangular rubber 40. The end 42be of the folding-back portion 42b is located radially outside the outer end PR of the rim R.

[0215] As mentioned above, the carcass cord 44 is thicker than existing cords. There is concern that deformation may be concentrated at the end 42be of the folded-back portion 42b.

[0216] like Figure 5 As shown, in this tire 2a, a recess 62 is provided on the outer surface 2G of the tire. The recess 62 is provided on the outer surface 2G of the tire between the reference position PF and the outer end position PS of the contact surface.

[0217] Figure 6 This refers to a portion of the outer surface 2G of tire 2a. Figure 6 This is a developed view of the portion where the recessed part 62 is located. Figure 6 In the diagram, the left-right direction represents the circumferential direction of tire 2a. The up-down direction represents the radial direction of tire 2a.

[0218] like Figure 6 As shown, a plurality of recesses 62 are provided on the outer surface 2G of the tire, arranged circumferentially. These recesses 62 are arranged at equal intervals. The recesses 62 are rectangular. The recesses 62 are longer circumferentially and shorter radially.

[0219] When tire 2a travels, the recess 62 cuts through the airflow. The airflow near the recess 62 is disrupted. As a result, the temperature rise near the recess 62 can be suppressed.

[0220] like Figure 5 As shown, the recess 62 is located near the end 42be of the folded-back portion 42b. Even if strain is concentrated at the end 42be of the folded-back portion 42b, the temperature rise is suppressed because the recess 62 promotes heat dissipation. In this tire 2a, good durability and low rolling resistance are maintained. From this point of view, when the end 42be of the folded-back portion 42b is located radially outside the outer end PR of the rim R, it is preferable to provide the recess 62 near the end 42be of the folded-back portion 42b.

[0221] exist Figure 5 The length represented by the symbol DF is the shortest distance from the recessed part 62 to the folded-back part 42b.

[0222] From the viewpoint of maintaining good durability and low rolling resistance, the shortest distance DF is preferably 10 mm or less. From the viewpoint that the recess 62 can fully exert its heat dissipation effect, the shortest distance DF is preferably 2 mm or more.

[0223] Figure 6 The length represented by the symbol DL is the length of the recess 62. The length DL is measured along the radial centerline of the width of the recess 62. The length represented by the symbol DW is the width of the recess 62. The width DW is measured along the circumferential centerline of the recess 62.

[0224] From the viewpoint that the recess 62 can fully exert its heat dissipation effect, the length DL of the recess 62 is preferably 15 mm or more, more preferably 17 mm or more. This length DL is preferably 30 mm or less, more preferably 23 mm or less.

[0225] From the same point of view, the width DW of the recess 62 is preferably 8.5 mm or more, more preferably 8.8 mm or more. This width DW is preferably 12 mm or less, more preferably 9.2 mm or less.

[0226] Figure 7 This shows a cross-section of the recessed portion 62. Figure 6 The VII-VII line includes the radial width centerline of the recess 62. Figure 7 The length represented by the symbol DD is the depth of the recessed portion 62.

[0227] In this tire 2a, from the viewpoint that the recess 62 can fully exert its heat dissipation effect, the depth DD of the recess 62 is preferably 1.5 mm or more, more preferably 1.8 mm or more. This depth DD is preferably 2.5 mm or less, more preferably 2.2 mm or less.

[0228] Figure 8 express Figure 1 The modified example of tire 2 shown (hereinafter referred to as tire 2b). Figure 8 This represents a portion of the radial section of tire 2b.

[0229] exist Figure 8 In the tire 2b shown, the end 42be of the folded-back portion 42b is located radially outside the maximum width position PW. The tire carcass 12 of this tire 2b has a high-level folding structure.

[0230] The tire carcass 12 is particularly helpful in improving the rigidity of the sidewall. In this tire 2b, with... Figure 1 Compared to tire 2 shown, the mass is slightly increased, but this results in improved handling stability.

[0231] Compared to existing tire carcasses consisting of two carcass plies with a raised structure, this carcass 12 is lighter. Even in this tire 2b, the appearance quality is not compromised, achieving weight reduction while suppressing the reduction in the strength of the carcass 12.

[0232] Figure 9 express Figure 8 The modified version of tire 2b shown is referred to as tire 2c. Figure 9 This represents a portion of the radial section of tire 2c.

[0233] like Figure 9 As shown, in this tire 2c, a recess 62a is provided near the end 42be of the fold-back portion 42b. This recess 62a is formed by... Figure 5 The recessed portion 62 shown has the same specifications.

[0234] As mentioned above, the carcass cord 44 is thicker than existing cords. There is concern that deformation may be concentrated at the end 42be of the folded-back portion 42b.

[0235] In this tire 2c, the recess 62a is located near the end 42be of the folded-back portion 42b. Even if deformation is concentrated at the end 42be of the folded-back portion 42b, the recess 62a promotes heat dissipation, thus suppressing temperature rise. In this tire 2c, good durability and low rolling resistance are maintained. From this point of view, when the tire carcass 12 has a raised structure, it is preferable to provide the recess 62a in a region extending from 10 mm radially outward from the end 42be of the folded-back portion 42b to 10 mm radially inward. Furthermore, in this case, the shortest distance DF from the recess 62a to the end 42be of the folded-back portion 42b is more preferably 2 mm or more and 10 mm or less.

[0236] [Second Implementation]

[0237] Figure 10 This represents a portion of the tire 72 according to the second embodiment of the present invention. This tire 72 is a pneumatic tire for passenger cars.

[0238] In this tire 72, the same as Figure 1 The tire 2 shown has a different bead 74 than the tire bead 10. Therefore, there are slight changes to the structure of the overlap portion 8, the tire carcass 12, and the bead wrapping 18 in the tire 2, but the structure of the tire 72 other than the bead 74 is the same. Figure 1 The structure of tire 2 shown is largely the same. The components of tire 72 other than the bead 74 are labeled as follows: Figure 1 The tire shown is the same symbol as tire 2, and its detailed description is omitted.

[0239] In this tire 72, the carcass 12 is also composed of a carcass ply 42. This carcass 12 contributes to the weight reduction of the tire 72.

[0240] Because the carcass ply 42 contains carcass cords with a total fineness of 6000 dtex or more, the carcass 12, despite being composed of only one carcass ply 42, can suppress the reduction in the strength of the carcass 12. Because the carcass ply 42 contains carcass cords with a total fineness of 9000 dtex or less, the carcass 12 can contribute to the weight reduction of the tire 72.

[0241] The separator layer 22 is located between the tire carcass 12 and the inner liner layer 20, and between the first bead 74 and the second bead 74. The separator layer 22 prevents the inner liner layer 20 from merging into the tire carcass cords of the outer layer. The separator layer 22 helps to suppress the occurrence of open lines. Good appearance quality can be obtained in this tire 72.

[0242] Even in this tire 72, the appearance quality is not compromised, and lightweighting is achieved while suppressing the reduction in the strength of the tire carcass 12.

[0243] The bead 74 of tire 72, like bead 10, has a core 76 and a triangular rubber 78. The core 76 has the same structure as the core 38 of bead 10. The core 76 extends circumferentially. The triangular rubber 78 is located radially outward of the core 76. The triangular rubber 78 tapers radially outward overall. The outer end 78e of the triangular rubber 78 is located radially inward of the maximum width position PW. The outer end 78e of the triangular rubber 78 is the outer end 74e of bead 74. Bead 74 is located radially inward of the maximum width position PW.

[0244] In this tire 72, the triangular rubber 78 consists of two components. The triangular rubber 78 includes a first triangular rubber 80 and a second triangular rubber 82.

[0245] The first triangular adhesive 80 is located radially outward of the core 76. The first triangular adhesive 80 is stacked on the core 76. The first triangular adhesive 80 gradually tapers in the radially outward direction. The material of the first triangular adhesive 80 is the same as that of the aforementioned triangular adhesive 40. The length of the first triangular adhesive 80 is more than 5 mm and less than 20 mm. The first triangular adhesive 80 is shorter than the triangular adhesive 40.

[0246] like Figure 10 As shown, the core 76 and the first triangular rubber 80 are located between the ply body 42a and the fold-back portion 42b. On the radially outer portion of the first triangular rubber 80, the fold-back portion 42b is directly attached to the ply body 42a. The core 76 and the first triangular rubber 80 are surrounded by the carcass ply 42.

[0247] The second triangular rubber 82 is located radially outside the first triangular rubber 80. The second triangular rubber 82 is located between the tire carcass 12 and the overlap portion 8. The end 42be of the folded-back portion 42b is sandwiched between the ply body 42a and the second triangular rubber 82. The outer end 18se of the bead wrap 18 is located between the folded-back portion 42b and the second triangular rubber 82. Figure 10 As shown, the second triangular adhesive 82 is thicker near the outer end 80e of the first triangular adhesive 80. The second triangular adhesive 82 gradually tapers outward from its thicker portion.

[0248] exist Figure 1 In the tire 2 shown, the bead 10 is not a single piece, but rather a portion surrounded by the carcass ply 42. In this tire 2, compared to a tire where the bead is entirely surrounded by the carcass ply, the secondary moment of force in the tire section is smaller, resulting in reduced rigidity of the bead portion. With lower rigidity at the bead portion, rotational force is reduced. In this situation, for example, during cornering, if a high load is applied to the vehicle, the pedaling of tire 2 becomes ineffective, and the vehicle is at risk of tipping over.

[0249] exist Figure 8 In the tire 2b shown, the bead 10 is entirely surrounded by the carcass ply 42. However, as mentioned above, deformation is concentrated at the end 42be of the folded portion 42b. This concentration of deformation reduces the durability of the tire 2.

[0250] In this tire 72, as described above, with the core 76 and the first triangular rubber 80 surrounded by the carcass ply 42, the fold-back portion 42b of the first triangular rubber 80 is directly attached to the ply body 42a on its radially outer side. The second triangular rubber 82 is disposed radially outer of the first triangular rubber 80 via the fold-back portion 42b.

[0251] The structure of the bead 74 in this tire 72 increases the section secondary moment. Because the carcass cords use thicker cords than before, in this tire 72, compared to... Figure 1 Compared to tire 2 shown, it achieves a larger section second moment. Due to the large rotational force generated, the vehicle is less prone to overturning even under high loads during cornering. This tire 2 achieves improved rollover resistance.

[0252] Because the end 42be of the folded-back portion 42b is covered by the second triangular rubber 82, damage caused by strain concentration at the end 42be of the folded-back portion 42b is difficult to occur. This tire 72 can suppress the reduction of durability.

[0253] In this tire 72, the tire carcass 12, which is composed of a single carcass ply 42, can fully perform its function.

[0254] exist Figure 10 In the diagram, the length indicated by the symbol TS is the thickness of the second triangular rubber 82 at the reference position PF. The thickness TS is measured along the normal to the outer surface of the tire carcass 12 passing through the reference position PF.

[0255] In this tire 72, the reference position PF is located radially between the maximum width position PW and the rim R. This reference position PF is also located radially between the outer end 80e of the first triangular rubber 80 and the outer end 82se of the second triangular rubber 82.

[0256] In this tire 72, the thickness TS of the second triangular rubber 82 at the reference position PF is preferably 2.5 mm or more and 4.5 mm or less.

[0257] By setting the thickness TS to 2.5 mm or more, the second triangular rubber 82 can effectively contribute to the generation of rotational force. This tire 72 achieves good rollover resistance. From this perspective, the thickness TS is more preferably 3.0 mm or more, and even more preferably 3.5 mm or more.

[0258] By setting the thickness TS to 4.5 mm or less, the impact of the second triangular rubber 82 on the quality can be suppressed. This achieves weight reduction in the tire 72. From this perspective, the thickness TS is preferably 4.0 mm or less.

[0259] In this tire 72, it is preferable that the complex elastic modulus E*2 of the second triangular rubber 82 is equal to or greater than that of the complex elastic modulus E*1 of the first triangular rubber 80. This significantly increases the section second moment. In this tire 72, due to the generation of high rotational force, good rollover resistance is achieved. From this viewpoint, the complex elastic modulus E*2 of the second triangular rubber 82 is preferably higher than that of the first triangular rubber 80. Specifically, the ratio of the complex elastic modulus E*2 to the complex elastic modulus E*1 (E*2 / E*1) is more preferably 1.3 or higher. From the viewpoint of suppressing deformation at the boundary between the second triangular rubber 82 and the first triangular rubber 80 and maintaining good durability, the ratio (E*2 / E*1) is preferably 3.5 or less, more preferably 3.0 or less.

[0260] exist Figure 10 The length represented by the symbol FS is the radial distance from the inner end 82ue of the second triangular rubber 82 to the end 42be of the folded-back portion 42b. The length represented by the symbol BS is the radial distance from the bead baseline BBL to the outer end 82se of the second triangular rubber 82.

[0261] In this tire 72, the radial distance FS from the inner end 82ue of the second triangular rubber 82 to the end 42be of the folding portion 42b is preferably 10 mm or more and 40 mm or less.

[0262] By setting the radial distance FS to 10 mm or more, the end 42be of the folded portion 42b is positioned at an appropriate distance from the inner end 82ue of the second triangular rubber 82. This suppresses damage caused by strain concentration at the end 42be of the folded portion 42b. Good durability is maintained in this tire 72. From this perspective, a radial distance FS of 20 mm or more is more preferable.

[0263] By setting the radial distance FS to 40 mm or less, the length of the folded portion 42b is appropriately maintained. In this tire 72, the impact of the folded portion 42b on the mass can be suppressed. Lightweighting is achieved in this tire 72. From this point of view, the radial distance FS is more preferably 30 mm or less.

[0264] In this tire 72, the radial distance BS from the bead baseline BBL to the outer end 82se of the second triangular rubber 82 is preferably 35 mm or more and 55 mm or less.

[0265] By setting the radial distance BS to 35 mm or less, the second triangular rubber 82 can contribute to the increase of the section secondary moment. This maintains good rollover resistance in the tire 72. From this perspective, a radial distance BS of 40 mm or more is more preferable.

[0266] By setting the radial distance BS to 55 mm or less, the volume of the second triangular rubber 82 is appropriately maintained. In this tire 72, since the heat generation of the second triangular rubber 82 is suppressed, low rolling resistance can be maintained. From this point of view, the radial distance BS is more preferably 50 mm or less.

[0267] As described above, according to the present invention, a tire is obtained that does not compromise appearance quality and achieves lightweighting while suppressing the reduction of tire body strength.

[0268]

Example

[0269] The present invention will be further described in detail below through examples, etc., but the present invention is not limited to these examples.

[0270] [Example 1]

[0271] Obtained with Figure 1 The basic structure shown is for a passenger car pneumatic tire with the specifications shown in Table 1 below (tire name = 245 / 50R18).

[0272] In this Example 1, a cord made of polyethylene terephthalate fiber is used as the carcass cord. The cord structure of this carcass cord is 3300 dtex / 2 (total fineness = 6600 dtex). Cords with a total fineness of 6000 dtex or higher are indicated by "Y" in the coarse cord column. The number of carcass cord layers in a 50mm width is 40.

[0273] The tire body is composed of a single tire body cord layer.

[0274] An isolation layer consisting of a pair of rubber layers is provided between the tire body and the inner liner.

[0275] The ratio (ta / td) of the thickness ta of the adhesive rubber located between the separator layer and the carcass cord to the thickness td of the separator layer is 0.4.

[0276] The axial distance Lb from the outer end of the rubber layer to the end of the belt layer is 50 mm.

[0277] The ratio of the radial distance Hc from the end of the separator (inner end of the rubber layer) to the outer end of the triangular rubber to the tire profile height HS (Hc / HS) is 0.17.

[0278] The ratio of the complex elastic modulus E*r of the isolation layer to the complex elastic modulus E*t of the outer layer (E*r / E*t) is 1.0.

[0279] [Comparative Example 1]

[0280] Comparative Example 1 is an existing tire. The tire carcass consists of two carcass plies. The carcass cords are made of polyethylene terephthalate fibers (cord structure = 1100 dtex / 2). Cords with a total fineness of less than 6000 dtex are indicated by "N" in the coarse cord column. Each 50mm width of the carcass ply contains 48 carcass cords.

[0281] No isolation layer was used in Comparative Example 1.

[0282] [Comparative Example 2]

[0283] The same cords as in Example 1 were used for the carcass cords, and the tires of Comparative Example 2 were otherwise configured the same as in Comparative Example 1. In Comparative Example 2, the number of carcass cords in a 50mm width of the carcass ply was 40.

[0284] [Comparative Example 3]

[0285] Except that the tire carcass is composed of a single carcass ply, the tire of Comparative Example 3 is configured in the same way as Comparative Example 2. The position of the end of the folded-back section is set in the same way as in Example 1.

[0286] [Examples 2-3 and Comparative Examples 4-5]

[0287] Except for the ratio (ta / td) as shown in Tables 1-2 below, the tires of Examples 2-3 and Comparative Examples 4-5 were obtained by setting them up the same as in Example 1.

[0288] [Example 4]

[0289] Except for the axial distance Lb as shown in Table 2 below, the tire of Example 4 is set up in the same way as in Example 1.

[0290] [Example 5]

[0291] Except that the ratio (Hc / HS) is as shown in Table 2 below, the tire of Example 5 is obtained by setting it the same as in Example 4.

[0292] [Example 6]

[0293] Except that the ratio (E*r / E*t) is set as shown in Table 2 below, the tire of Example 6 is obtained by setting it the same as in Example 5.

[0294] [Tire Quality]

[0295] The mass of the tires was measured. The results are shown in the "Mass" column of Table 1-2 below, with Comparative Example 1 set to 100. The higher the value, the lighter the tire.

[0296] [Appearance Quality]

[0297] The surface condition of the inner surface of the tires was visually observed. One hundred tires were tested to confirm the number of tires with open seams, and the incidence rate was obtained. The results are shown in the "Appearance Quality" column of Table 1-2 below, with Comparative Example 1 as an index of 100. The higher the value, the lower the incidence rate.

[0298] [Pinch resistance]

[0299] According to section 6.1 "Tire Strength (Destruction Energy) Test" of JIS D4230, the destruction energy at the maximum width position of the tire carcass of a prototype tire under lateral support under rim (7.5J) and internal pressure (230kPa) conditions was determined using a plunger-type testing machine. The results are shown in the "Pinch Resistance" column of Table 1-2 below, with Comparative Example 1 as an index of 100. The higher the value, the better the pinch resistance.

[0300] [Durability]

[0301] The prototype tire was assembled onto a rim (size = 7.5J), inflated with air, and the internal pressure was set to 250 kPa. The tire was then mounted on a roller-type driving test machine. A longitudinal load of 9.54 kN was applied to the tire, causing it to travel at 100 km / h on the rollers (radius = 1.7 m). The distance traveled until tire damage was confirmed was measured. The results are shown in the "Durability" column of Table 1-2 below, with Comparative Example 1 set to 100. A higher value indicates better durability.

[0302] Rolling resistance

[0303] The rolling resistance coefficient (RRC) of the prototype tire was determined using a rolling resistance testing machine when it was driven on a roller at a speed of 80 km / h under the following conditions. The results are shown in the "RRC" column of Table 1-2 below, with Comparative Example 1 as the index of 100. The higher the value, the lower the rolling resistance of the tire.

[0304] Rim: 7.5J

[0305] Internal pressure: 210 kPa

[0306] Longitudinal load: 6.28kN

[0307] [Overall Performance]

[0308] Calculate the sum of the indices obtained from each evaluation. The results are shown in the "Overall" column of Table 1-2 below. The higher the value, the better.

[0309] Table 1

[0310]

[0311] Table 2

[0312]

[0313] As shown in Tables 1-2, in the embodiments, it was confirmed that lightweighting was achieved without compromising appearance quality and suppressing the reduction of tire strength. The superiority of the present invention can be seen from these evaluation results.

[0314] [Industry Applicability]

[0315] The lightweighting techniques described above can also be applied to various types of tires.

Claims

1. A tire, characterized in that, have: The tire tread is in contact with the road surface; A pair of sidewalls, which are connected to the ends of the tread and located radially inside the tread; A pair of tire beads located radially inside the tire sidewall; The tire carcass is located inside the tread and the pair of sidewalls, and is positioned between the first and second bead of the pair of bead pairs. A belt layer, which is located radially between the tread and the carcass; Inner liner, which is located inside the tire carcass; and An isolation layer, located between the tire carcass and the inner liner, Each of the aforementioned bead groups has a core and a triangular rubber strip located radially outside the core. The tire body is composed of a single tire body ply. The tire carcass ply has: a ply body that is positioned between the core of the first bead and the core of the second bead; and a pair of fold-back portions that are connected to the ply body and fold back at the core. The carcass ply consists of multiple parallel carcass cords and adhesive rubber covering these carcass cords. The total fineness of the tire cords is between 6000 dtex and 9000 dtex. The insulating layer is located between the first bead and the second bead. The ratio of the thickness of the adhesive rubber located between the separator layer and the tire carcass cord to the thickness of the separator layer is 0.2 to 0.

6. The radially inner end of the isolation layer is located radially outer of the outer end of the radially outer side of the triangular adhesive. The ratio of the radial distance from the radially inner end of the separator to the radially outer end of the triangular rubber to the tire profile height is 0.15 to 0.

35. The radially outer end of the fold-back portion is located radially inner to the radially inner end of the insulating layer. The ratio of the radial distance from the radially inner end of the isolation layer to the radially outer end of the folded-back portion to the radial distance from the radially inner end of the isolation layer to the radially outer end of the triangular adhesive is 1.2 or more and 2.0 or less.

2. The tire according to claim 1, characterized in that, The inner liner consists of an inner layer that forms the inner surface of the tire and an outer layer that is stacked on the outside of the inner layer. The inner layer is a crosslinked rubber composition containing butyl rubber. The outer layer is a crosslinked rubber composition comprising natural rubber. The ratio of the complex elastic modulus of the isolation layer to that of the outer layer is greater than 1.0 and less than 2.

0.

3. The tire according to claim 1 or 2, characterized in that, The insulating layer consists of a pair of rubber layers separated by the equatorial plane and along the axial direction. The outer end of the radially outer side of the rubber layer is located on the axially inner side of the end of the belt layer. The axial distance from the outer end of the radially outer side of the rubber layer to the end of the belt layer is more than 10 mm and less than 50 mm.

4. The tire according to claim 1 or 2, characterized in that, The ratio of the distance between the tire cords in the tire carcass ply to the outer diameter of the tire cord is more than 0.15 and less than 0.

45.

5. The tire according to claim 1 or 2, characterized in that, Multiple recesses arranged circumferentially are provided on the outer surface of the tire. The shortest distance from each recess to the radially outer end of the folded portion is more than 2 mm and less than 10 mm.

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