JP2014201169A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving turning performance at cornering traveling.SOLUTION: A pneumatic tire 1 includes: a carcass layer 13; a belt layer 14 arranged outside the tire radial direction of the carcass layer 13; and an inner liner 18 arranged on a tire inner peripheral surface. In addition, an average gauge Ga_in of the inner liner 18 in a region from a tire equator plane CL to a bead toe B in a vehicle width direction in an inner region and an average gauge Ga_out of the inner liner 18 in a region from the tire equator plane CL to a bead toe B in a vehicle width direction in an outer region have a relationship of Ga_in<Ga_out.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of improving turning performance during cornering traveling.

  In recent pneumatic tires, an inner liner made of a thermoplastic resin containing a rubber composition is being adopted. Such an inner liner can realize a weight reduction of several hundred grams by a single tire in addition to the original function of the inner liner that suppresses air leakage of the tire. As a conventional pneumatic tire including such an inner liner, a technique described in Patent Document 1 is known.

  Further, in recent pneumatic tires, there is a problem that the turning performance (steering stability performance) during cornering traveling should be improved. As a conventional pneumatic tire related to this problem, a technique described in Patent Document 2 is known.

JP 2005-343379 A JP 2007-253708 A

  An object of the present invention is to provide a pneumatic tire capable of improving turning performance during cornering traveling.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a carcass layer, a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and an inner liner disposed on a tire inner peripheral surface. An average tire Ga_in of the inner liner in a region from the tire equator plane to one bead toe and an average gauge Ga_out of the inner liner in a region from the tire equator plane to the other bead toe are Ga_in <Ga_out It has the relationship of these.

  When the pneumatic tire 1 according to the present invention is attached to a vehicle with the side having the average gauge Ga_in on the inner side in the vehicle width direction, the inner liner 18 has a thick structure (Ga_in <Ga_out) in the outer region in the vehicle width direction. Therefore, the rigidity of the outer region in the vehicle width direction is increased as compared with the configuration in which the inner liner 18 has a constant gauge on the left and right sides of the tire. Thereby, there exists an advantage which the turning performance (steering stability performance) of the tire at the time of cornering driving | running | working improves.

FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an explanatory view showing the configuration of the inner liner of the pneumatic tire shown in FIG. FIG. 3 is an explanatory view showing a modified example of the configuration of the average gauge of the inner liner shown in FIG. FIG. 4 is an explanatory view showing a modification of the configuration of the average gauge of the inner liner shown in FIG. FIG. 5 is an explanatory view showing a modified example of the configuration of the average gauge of the inner liner shown in FIG. 6 is an explanatory view showing a modification of the configuration of the average gauge of the inner liner shown in FIG. FIG. 7 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Pneumatic tire]
FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. This figure shows one side region in the tire radial direction. The figure shows a radial tire for a passenger car as an example of a pneumatic tire.

  In the figure, the cross section in the tire meridian direction means a cross section when the tire is cut along a plane including a tire rotation axis (not shown). Reference sign CL denotes a tire equator plane, which is a plane that passes through the center point of the tire in the tire rotation axis direction and is perpendicular to the tire rotation axis. Further, the tire width direction means a direction parallel to the tire rotation axis, and the tire radial direction means a direction perpendicular to the tire rotation axis. Further, the inside in the vehicle width direction and the outside in the vehicle width direction indicate directions with respect to the vehicle width direction when the tire is mounted on the vehicle.

  This pneumatic tire 1 has an annular structure centered on the tire rotation axis, and includes a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, and a tread rubber 15. A pair of side wall rubbers 16 and 16, a pair of rim cushion rubbers 17 and 17, and an inner liner 18 are provided (see FIG. 1).

  The pair of bead cores 11 and 11 is an annular member formed by bundling a plurality of bead wires, and constitutes the core of the left and right bead portions. The pair of bead fillers 12 and 12 are disposed on the outer circumference in the tire radial direction of the pair of bead cores 11 and 11 to reinforce the bead portion.

  The carcass layer 13 is bridged in a toroidal shape between the left and right bead cores 11 and 11 to form a tire skeleton. Further, both end portions of the carcass layer 13 are wound and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12. The carcass layer 13 is formed by rolling a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coat rubber, and has an absolute value of 80 [deg]. A carcass angle of 95 [deg] or less (inclination angle in the fiber direction of the carcass cord with respect to the tire circumferential direction).

  The belt layer 14 is formed by laminating a pair of cross belts 141 and 142 and a belt cover 143, and is arranged around the outer periphery of the carcass layer 13. The pair of cross belts 141 and 142 is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and has an absolute value of a belt angle of 20 [deg] or more and 40 [deg] or less. Have. Further, the pair of cross belts 141 and 142 have belt angles with different signs from each other (inclination angle of the fiber direction of the belt cord with respect to the tire circumferential direction), and are laminated so that the fiber directions of the belt cords cross each other. (Cross ply structure). The belt cover 143 is formed by rolling a plurality of belt cords made of steel or organic fiber material coated with a coat rubber, and has a belt angle of 45 [deg] or more and 70 [deg] or less in absolute value. Further, the belt cover 143 is disposed so as to be laminated on the outer side in the tire radial direction of the cross belts 141 and 142.

  The tread rubber 15 is disposed on the outer circumference in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute a tread portion of the tire. The pair of side wall rubbers 16 and 16 are respectively arranged on the outer side in the tire width direction of the carcass layer 13 to constitute left and right side wall portions. The pair of rim cushion rubbers 17, 17 are respectively disposed on the inner side in the tire radial direction of the wound portions of the left and right bead cores 11, 11 and the carcass layer 13, and constitute the contact surfaces of the left and right bead portions with respect to the rim flange.

  The inner liner 18 is a belt-like rubber sheet that is disposed on the inner peripheral surface of the tire and covers the inner peripheral surface of the carcass layer 13, and is attached to the inner peripheral surface of the carcass layer 13. The inner liner 18 suppresses oxidation due to exposure of the carcass layer 13 and prevents leakage of air filled in the tire.

  The inner liner 18 is made of, for example, butyl rubber, a thermoplastic resin containing a rubber composition, or the like. In particular, such a configuration is preferable in that the air pressure retention property of the tire can be improved and the tire weight can be reduced while ensuring the flexibility of the tire as compared with the configuration in which the inner liner 18 is made of butyl rubber.

  The inner liner 18 made of the above thermoplastic resin has, for example, (A) an air permeability coefficient of 25 × 10 ^ 12 [cc · cm / cm ^ 2 · sec · cmHg] or less and a Young's modulus exceeding 500 [MPa]. At least one thermoplastic resin is 10 [wt%] or more per weight of all polymer components, and (B) Young's modulus with an air permeability coefficient exceeding 25 × 10 ^ 12 [cc · cm / cm ^ 2 · sec · cmHg] Is at least 10 [% by weight] of at least one elastomer component of 500 [MPa] or less per total polymer component weight, and the total amount (A) + (B) of component (A) and component (B) is the total polymer component weight Tire with an air permeation coefficient of 25 × 10 ^ 12 [cc · cm / cm ^ 2 · sec · cmHg] or less and a Young's modulus of 1 to 500 [MPa] A polymer composition.

  The thermoplastic resin blended as the component (A) in this polymer composition has an air permeability coefficient of 25 × 10 ^ 12 [cc · cm / cm ^ 2 · sec · cmHg] or less, preferably 0.1 × 10 ^. Any thermoplasticity within a range of 12 to 10 × 10 ^ 12 [cc · cm / cm ^ 2 · sec · cmHg] and a Young's modulus exceeding 500 [MPa], preferably within a range of 500 to 3000 [MPa]. A resin can be used, and the amount of the resin is 10 [wt%] or more, preferably 20 to 85 [wt%], based on the total weight of the polymer components including the resin and rubber.

  Examples of the thermoplastic resin include the following thermoplastic resins, and these thermoplastic resins or any resin mixture containing these thermoplastic resins.

  Polyamide resin (for example, nylon 6 (N6), nylon 66 (N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12), nylon 610 (N610), nylon 612 (N612), nylon 6 / 66 copolymer (N6 / 66), nylon 6/66/610 copolymer (N6 / 66/610), nylon MXD6 (MXD6), nylon 6T, nylon 6 / 6T copolymer, nylon 66 / PP Polymer, nylon 66 / PPS copolymer), polyester resin (for example, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, polyarylate (PAR), Polybutylene naphthalate (PBN), liquid crystal polyester Aromatic polyester such as polyoxyalkylene diimidic acid / polybutyrate terephthalate copolymer), polynitrile resins (for example, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / Styrene copolymer, methacrylonitrile / styrene / butadiene copolymer), polymethacrylate resin (for example, polymethyl methacrylate (PMMA), polyethyl methacrylate), polyvinyl resin (for example, vinyl acetate (EVA), polyvinyl alcohol) (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer Body), cellulose resin (for example, cellulose acetate, cellulose acetate butyrate), fluorine resin (for example, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer) Coalesce (ETFE)), imide resins (for example, aromatic polyimide (PI)), and the like.

  As described above, these thermoplastic resins must have a specific air permeability coefficient, Young's modulus and blending amount. A material having a Young's modulus of 500 [MPa] or less and an air permeability coefficient of 25 × 10 ^ 12 [cc · cm / cm ^ 2 · sec · cmHg] or less is still industrially developed. If the air permeation coefficient exceeds 25 × 10 ^ 12 [cc · cm / cm ^ 2 · sec · cmHg], the air permeation resistance of the tire polymer composition decreases, and the air permeation of the tire decreases. It can no longer function as a prevention layer. Furthermore, when the blending amount of these thermoplastic resins is less than 10 [% by weight], the air permeation resistance similarly decreases, and it cannot be used as an air permeation preventive layer of a tire.

  The elastomer component blended as the component (B) in the above resin composition has an air permeability coefficient larger than 25 × 10 ^ 12 [cc · cm / cm ^ 2 · sec · cmHg] and a Young's modulus of 500 [ [MPa] Any elastomer or any blend of elastomers below, or reinforcing agents, fillers, cross-linking agents, softening agents generally incorporated into the elastomer for improving the dispersibility and heat resistance of the elastomer, etc. An elastomer composition to which a necessary amount of a compounding agent such as an agent, an anti-aging agent, or a processing aid is added, and the compounding amount is 10 per total weight of the total amount of the polymer component including the resin and the elastomer component constituting the air permeation prevention layer. [Wt%] or more, preferably 10 to 85 [wt%].

  The elastomer constituting such an elastomer component is not particularly limited as long as it has the above-described air permeability coefficient and Young's modulus, and examples thereof include the following.

  Diene rubber and hydrogenated products thereof (for example, NR, IR, epoxidized natural rubber, SBR, BR (high cis BR and low cis BR), NBR, hydrogenated NBR, hydrogenated SBR), olefin rubber (for example, ethylene propylene) Rubber (EPDM, EPM), maleic acid-modified ethylene propylene rubber (M-EPM), IIR, isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (ACM), ionomer), halogen-containing rubber (eg brominated) Butyl rubber (Br-IIR), chlorinated butyl rubber (Cl-IIR), brominated product of isobutylene paramethylstyrene copolymer (Br-IPMS), chloroprene rubber (CR), hydrin rubber (CHR, CHC), chlorosulfonated polyethylene ( CSM), chlorinated polyethylene (CM), male Acid-modified chlorinated polyethylene (M-CM)), silicone rubber (eg methyl vinyl silicone rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber), sulfur-containing rubber (eg polysulfide rubber), fluoro rubber (eg vinylidene fluoride rubber) Fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicon rubber, fluorine-containing phosphazene rubber), thermoplastic elastomer (for example, styrene elastomer, polyolefin elastomer, polyester elastomer, polyurethane elastomer, polyamide) Elastomers).

  In addition, it is a halogen (for example, Br, Cr, I) containing copolymer rubber of C4-C7 isomonoolefin and p-alkyl styrene as an elastomer component, and p-alkyl styrene content is 5 of all copolymer rubbers. Mooney viscosity of 5 to 25 [wt%], preferably 6.0 to 20 [wt%], halogen content of 1.0 [wt%] or more, preferably 1.0 to 5.0 [wt%] A copolymer rubber having an ML1 + 8 (125 [° C.]) of 30 or more, preferably 35 to 70 can be used. When this rubber is used, the weight ratio of the component (A) to the component (B) is (A) / (B) = 10/90 to 90/10, preferably 15/85 to 85/15.

  When the copolymer rubber has a p-alkylstyrene content of less than 5.5 [wt%], the air permeation resistance of the obtained tire polymer composition is unfavorable, and conversely, 25 [wt%]. Exceeding this is not preferred because it tends to become brittle at low temperatures. Further, when the halogen content is less than 1.0 [wt%], the mechanical strength such as tensile strength is lowered, which is not preferable. When the Mooney viscosity is less than 30, the air permeation resistance is also lowered, which is not preferable. Furthermore, if the blending ratio (weight basis) of the component (A) / (B) is less than 10/90, it is not preferable because the air permeation resistance also decreases, and conversely if it exceeds 90/10, the flexibility decreases. Therefore, it is not preferable.

  When the above-mentioned specific thermoplastic resin and the elastomer component are different in compatibility, it is preferable to make them compatible with each other using a suitable compatibilizer as the third component. By mixing a compatibilizing agent with the system, the interfacial tension between the thermoplastic resin and the elastomer component decreases, and as a result, the rubber particle size forming the dispersion layer becomes fine. It will be expressed more effectively. As such a compatibilizing agent, generally, a copolymer having a structure of one or both of a thermoplastic resin and an elastomer component, or an epoxy group, a carbonyl group, a halogen capable of reacting with the thermoplastic resin or the elastomer component are used. A copolymer having a group, an amino group, an oxazoline group, a hydroxyl group and the like can be taken. These may be selected depending on the thermoplastic resin to be mixed and the kind of the elastomer component, and those usually used include styrene / ethylene-butylene block copolymer (SEBS) and its maleic acid modified product, EPDM, EPDM / styrene or EPDM / acrylonitrile graft copolymer and its maleic acid modified product, styrene / maleic acid copolymer, reactive phenoxy resin and the like can be mentioned. The amount of the compatibilizing agent is not particularly limited, but is preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the polymer component (the total of the thermoplastic resin and the elastomer component).

  The composition ratio between the specific thermoplastic resin (A) and the elastomer component (B) may be appropriately determined depending on the balance of film thickness, air permeation resistance and flexibility, but a preferred range is 10/90 by weight. It is -90/10, More preferably, it is 20 / 80-85 / 15.

[Inner liner gauge]
FIG. 2 is an explanatory view showing the configuration of the inner liner of the pneumatic tire shown in FIG. The figure shows the gauge distribution of the inner liner 18 in the vehicle width direction outer region and the vehicle width direction inner region with the tire equator plane CL as a boundary.

  In the pneumatic tire 1, as shown in FIG. 1, a region of 50 [%] of the tire cross-section height SH around the tire maximum width position A is referred to as a sidewall portion, and the tire is more than the sidewall portion. The region on the radially outer side is called a tread portion, and the region on the tire radial direction inner side than the sidewall portion is called a bead portion.

  The tire cross-section height SH is a half of the difference between the tire outer diameter and the rim diameter. The tire cross-section height SH is measured by attaching the tire to a specified rim and applying a specified internal pressure, and at no load. The tire maximum width position A refers to the maximum width position of the tire cross-sectional width specified by JATMA. Note that the tire cross-sectional width is measured as a no-load state while applying a specified internal pressure by mounting the tire on a specified rim.

  The specified rim refers to an “applied rim” defined in JATMA, a “Design Rim” defined in TRA, or a “Measuring Rim” defined in ETRTO. The specified internal pressure means “maximum air pressure” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The specified load means “maximum load capacity” defined in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined in TRA, or “LOAD CAPACITY” defined in ETRTO. However, in JATMA, in the case of tires for passenger cars, the specified internal pressure is air pressure 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

  In this pneumatic tire 1, as shown in FIG. 2, the inner liner 18 has different average gauges Ga_in and Ga_out in the vehicle width direction inner region and the vehicle width direction outer region with the tire equatorial plane CL as a boundary. Have. Specifically, in FIG. 1, the average gauge Ga_in of the inner liner 18 in the region from the tire equatorial plane CL to the bead toe B on the inner side in the vehicle width direction, and the inner liner 18 in the region from the tire equatorial plane CL to the other bead toe B. The average gauge Ga_out of the above has a relationship of Ga_in <Ga_out.

  The bead toe B refers to a point that becomes a toe when the bead portion is viewed as a human foot in a sectional view in the tire meridian direction.

  The average gauge is measured as an average value of the gauge of the inner liner 18 in a sectional view in the tire meridian direction. At this time, the gauge of the inner liner 18 is measured by excluding uneven portions locally formed on the inner liner 18 and locally raised portions due to bonding of rubber sheets. Further, the gauge of the coated rubber of the carcass layer 13 is not included in the gauge of the inner liner 18.

  For example, in the configuration of FIG. 1, the inner liner 18 is disposed so as to cover the entire area of the inner circumferential surface of the tire, and in a cross-sectional view in the tire meridian direction, from one bead toe B through the tire equatorial plane CL to the other bead toe B. Extends continuously. The average gauges Ga_in and Ga_out of the inner liner 18 in the left and right regions of the tire with the tire equatorial plane CL as the boundary have a relationship of Ga_in <Ga_out as described above.

  In addition, as shown in FIG. 2, the gauge of the inner liner 18 gradually increases from the inner region in the vehicle width direction toward the outer region in the vehicle width direction at least in the region where the outer cross belt 142 is disposed. For this reason, the inner liner 18 has a non-uniform gauge in the region where the outer cross belt 142 is disposed.

  Specifically, the inner liner 18 has a belt-like first rubber sheet covering the tread portion and a pair of belt-like left and right second rubber sheets covering the sidewall portion to the bead portion. The buttress part is configured to be bonded together while being wrapped (not shown). Further, as shown in FIG. 2, the first rubber sheet of the tread portion has a structure in which the gauge is gradually increased from a predetermined reference value as it goes from the vehicle width direction inner region to the vehicle width direction outer region. ing. Moreover, the left and right second rubber sheets have a constant gauge that serves as a reference value. For this reason, the gauge of the inner liner 18 is maximum at the tread end portion on the outer side in the tire width direction. Further, the gauge of the inner liner 18 is constant at the left and right sidewall portions and bead portions.

  In this pneumatic tire 1, the inner liner 18 has a thick structure (Ga_in <Ga_out) in the outer region in the vehicle width direction, so that the inner liner 18 has a constant gauge in the left and right regions of the tire. The rigidity of the outer region in the vehicle width direction increases. Thereby, the turning performance of the tire during cornering traveling is improved.

  In the above configuration, the average gauges Ga_in and Ga_out of the inner liner 18 preferably have a relationship of 0.05 [mm] ≦ Ga_out−Ga_in ≦ 0.5 [mm]. Thereby, the rigidity difference in the tire right and left region is appropriately formed. In particular, when the inner liner 18 is made of a thermoplastic resin containing a rubber composition, the average gauges Ga_in and Ga_out of the inner liner 18 have a relationship of 0.05 [mm] ≦ Ga_out−Ga_in ≦ 0.19 [mm]. It is preferable to have. Since the thermoplastic resin has higher rigidity than butyl rubber, even if the average gauge difference (Ga_out−Ga_in) is used, a difference in rigidity in the left and right regions of the tire can be appropriately formed. In addition, by setting the upper limit of the average gauge difference small, it is possible to appropriately ensure the tire uniformity and riding comfort.

  Further, in the above configuration, in the arrangement region of the outer cross belt (the cross belt on the outer side in the tire radial direction of the pair of cross belts 141 and 142) 142 in the vehicle width direction inner region with the tire equatorial plane CL as a boundary. The average gauge Ga_in_be of the inner liner 18 and the average gauge Ga_out_be of the inner liner 18 in the outer region in the vehicle width direction preferably have a relationship of Ga_in_be <Ga_out_be. Specifically, it is preferable that the average gauges Ga_in_be and Ga_out_be of the inner liner 18 in the arrangement region of the outer cross belts 142 have a relationship of 0.05 [mm] ≦ Ga_out_be−Ga_in_be ≦ 0.30 [mm].

  At this time, the gauge D_in of the inner liner 18 at the inner end in the vehicle width direction of the outer cross belt 142 and the gauge D_out of the inner liner 18 at the outer end in the vehicle width direction are 1.5 ≦ D_out / D_in. It is preferable to have a relationship of ≦ 5.0, and it is more preferable to have a relationship of 2.0 ≦ D_out / D_in ≦ 3.0.

  The arrangement | positioning area | region of the outer side cross belt 142 means the area | region divided by the perpendicular drawn down from the right-and-left edge part of the outer side cross belt 142 to a tire inner peripheral surface in the cross sectional view of a tire meridian direction.

  In general, the outer cross belt 142 has a strong influence on the turning performance of the tire. Therefore, the turning performance of the tire can be effectively improved by setting the average gauge Ga_out_be of the inner liner 18 in the vehicle width direction outer region large in at least the region where the outer cross belt 142 is disposed.

[Modification]
3-6 is explanatory drawing which shows the modification of a structure of the average gauge of the inner liner described in FIG.

  In the configuration of FIG. 2, as described above, the inner liner 18 has three rubber sheets: a first rubber sheet that covers the tread portion and a pair of left and right second rubber sheets that cover the sidewall portion and the bead portion. doing.

  However, the present invention is not limited to this, and the inner liner 18 may have two or four or more rubber sheets to cover the tread portion, the sidewall portion, and the bead portion. Moreover, the inner liner 18 may be comprised from a single rubber sheet. In such a configuration, the gauge of each rubber sheet is appropriately adjusted in order to satisfy the above average gauge requirement (Ga_in <Ga_out).

  For example, in the configuration of FIG. 3, the inner liner 18 has a belt-shaped outer rubber sheet that covers an outer region in the vehicle width direction, and a belt-shaped inner rubber sheet that covers an inner region in the vehicle width direction. The equator plane CL (or in the vicinity of the tire equator plane CL) is laminated and bonded together (not shown). The outer rubber sheet has a constant gauge larger than the reference value, and the inner rubber sheet has a constant gauge that becomes the reference value. Then, by arranging the thick outer rubber sheet on the outer side in the vehicle width direction, the relationship between the average gauges on the left and right sides of the tire (Ga_in <Ga_out) is formed. For this reason, in the tire right and left regions, the inner liner 18 has a uniform and large gauge in the entire region from the tread portion to the bead portion. In such a configuration, since the outer rubber sheet and the inner rubber sheet have a constant gauge, the inner liner 18 can be easily configured as compared with a configuration that employs a rubber sheet in which the gauge changes partially. Further, it is easy to adjust the average gauges Ga_in and Ga_out of the inner liner 18 in the left and right regions of the tire.

  In the configuration of FIG. 4, the inner liner 18 has a belt-like first outer rubber sheet that covers the tread portion in the outer region in the vehicle width direction, and the second outer surface that covers from the sidewall portion to the bead portion in the outer region in the vehicle width direction. It has a rubber sheet and a belt-shaped inner rubber sheet that covers the inner region in the vehicle width direction, and is configured by laminating these rubber sheets while wrapping each other (not shown). The first outer rubber sheet has a constant gauge larger than the reference value, and the second outer rubber sheet and the inner rubber sheet have a constant gauge that becomes the reference value. The thick first outer rubber sheet is arranged in the tread portion of the outer region in the vehicle width direction, thereby forming an average gauge relationship (Ga_in <Ga_out) on the left and right sides of the tire. In addition, the inner liner 18 has a uniform gauge in the region from the sidewall portion to the bead portion in the vehicle width direction outer region and the vehicle width direction inner region. In such a configuration, particularly, in the sidewall portion, the average gauge Ga_in_si of the inner liner 18 in the inner region in the vehicle width direction and the average gauge Ga_out_si of the inner liner 18 in the outer region in the vehicle width direction are substantially the same (0 ≦ | Ga_out_si). -Ga_in_si | ≦ 0.19 [mm]. This ensures proper tire uniformity and riding comfort.

  In the configuration of FIG. 5, the inner liner 18 has a belt-like first outer rubber sheet that covers from the tread portion in the vehicle width direction outer region to the sidewall portion, and a second outer surface that covers the bead portion in the vehicle width direction outer region. It has a rubber sheet and a belt-shaped inner rubber sheet that covers the inner region in the vehicle width direction, and is configured by laminating these rubber sheets while wrapping each other (not shown). The first outer rubber sheet has a constant gauge larger than the reference value, and the second outer rubber sheet and the inner rubber sheet have a constant gauge that becomes the reference value. The thick first outer rubber sheet is arranged from the tread portion in the vehicle width direction outer side region to the sidewall portion, thereby forming an average gauge relationship (Ga_in <Ga_out) on the left and right sides of the tire. In such a configuration, by providing a difference in the average gauge on the left and right sides of the tire in both the tread portion and the sidewall portion, the difference in rigidity between the left and right sides of the tire is compared with a configuration in which only the tread portion has a difference in the average gauge on the left and right sides of the tire. Can be adjusted easily.

  In the configuration of FIG. 6, a belt-shaped first rubber sheet that covers the entire tread portion, an outer second rubber sheet that covers the sidewall portion in the vehicle width direction outer region, and a bead portion in the vehicle width direction outer region are covered. An outer third rubber sheet, an inner second rubber sheet that covers the sidewall portion in the inner region in the vehicle width direction, and an inner third rubber sheet that covers the bead portion in the inner region in the vehicle width direction. They are configured to be bonded together while lapping each other (not shown). In addition, the outer second rubber sheet has a constant gauge larger than the reference value, and the other rubber sheets have a constant gauge that becomes the reference value, whereby the relationship between the average gauges on the left and right sides of the tire (Ga_in <Ga_out) Is formed. Thus, the inner liner 18 may have a uniform gauge at the tread portion and different gauges at the left and right sidewall portions.

[effect]
As described above, the pneumatic tire 1 includes the carcass layer 13, the belt layer 14 disposed on the outer side in the tire radial direction of the carcass layer 13, and the inner liner 18 disposed on the tire inner peripheral surface ( (See FIG. 1). Further, the average gauge Ga_in of the inner liner 18 in the region from the tire equator plane CL to one of the bead toes B (in FIG. 1, the vehicle width direction inner region) and the other from the tire equator surface CL (in FIG. The average gauge Ga_out of the inner liner 18 in the region up to the bead toe B in the region) has a relationship of Ga_in <Ga_out (see FIGS. 2 to 6).

  In such a configuration, when the pneumatic tire 1 is attached to the vehicle with the side having the average gauge Ga_in on the inner side in the vehicle width direction, the inner liner 18 has a thick structure (Ga_in <Ga_out) in the outer region in the vehicle width direction. Therefore, the rigidity of the outer region in the vehicle width direction is increased as compared with the configuration in which the inner liner 18 has a constant gauge on the left and right sides of the tire. Thereby, there exists an advantage which the turning performance (steering stability performance) of the tire at the time of cornering driving | running | working improves.

  In addition, the pneumatic tire 1 has a designation of the mounting direction to be mounted on the vehicle with the side having the average gauge Ga_in inward in the vehicle width direction (see FIG. 1). The designation of the mounting direction can be displayed by, for example, a mark or unevenness provided on the sidewall portion of the tire, or a catalog attached to the tire. When the pneumatic tire 1 is mounted on the vehicle in such a mounted state, there is an advantage that the effect of improving the turning performance of the tire described above can be obtained.

  Moreover, in this pneumatic tire 1, the inner liner 18 consists of a thermoplastic resin containing a rubber composition. A thermoplastic resin has high rigidity compared with butyl rubber, and is lightweight. Therefore, by forming the relationship between the average gauges Ga_in and Ga_out on the left and right sides of the tire using the inner liner 18 made of a thermoplastic resin, there is an advantage that the tire can be reduced in weight while ensuring the rigidity of the tire appropriately.

  In the pneumatic tire 1, the average gauges Ga_in and Ga_out of the inner liner 18 have a relationship of 0.05 [mm] ≦ Ga_out−Ga_in ≦ 0.5 [mm]. Thereby, there exists an advantage by which the relationship (Ga_in <Ga_out) of the average gauge Ga_in of the tire right and left, Ga_out is optimized. That is, when 0.05 [mm] ≦ Ga_out−Ga_in, the difference in rigidity between the left and right tires is appropriately secured, and when Ga_out−Ga_in ≦ 0.5 [mm], the tire uniformity is ensured. .

  Further, in this pneumatic tire 1, the average gauge Ga_in_be of the inner liner 18 in one area (in the vehicle width direction inner side in FIG. 1) of the arrangement area of the outer cross belt 142 with the tire equatorial plane CL as a boundary, The average gauge Ga_out_be of the inner liner 18 in the region (in the vehicle width direction outer side in FIG. 1) has a relationship of Ga_in_be <Ga_out_be. The outer cross belt 142 has a strong influence on the turning performance of the tire. Therefore, when the inner liner 18 has the above-described configuration in the region where the outer cross belt 142 is disposed, there is an advantage that a difference in rigidity between the left and right tires can be effectively formed.

  In the pneumatic tire 1, the gauge of the inner liner 18 is directed from one side to the other side in the tire width direction (in FIG. 1, from the vehicle width direction inner side to the vehicle width direction outer side) in the arrangement region of the outer cross belt 142. Gradually increase. The outer cross belt 142 has a strong influence on the turning performance of the tire. Therefore, when the inner liner 18 has the above-described configuration in the region where the outer cross belt 142 is disposed, there is an advantage that a difference in rigidity between the left and right tires can be effectively formed.

  Further, in the pneumatic tire 1, the average gauge Ga_in_si of the inner liner 18 in one side wall portion (in the vehicle width direction in FIG. 1) and the other side wall portion (in the vehicle width direction outer side in FIG. 1). The average gauge Ga_out_si of the inner liner 18 has a relationship of 0 ≦ | Ga_out_si−Ga_in_si | ≦ 0.19 [mm]. In such a configuration, the average gauges Ga_in_si and Ga_out_si of the inner liners 18 on the left and right sides of the tire in the sidewall portion are set to be substantially the same (see FIG. 4), so that the tire uniformity and riding comfort are appropriately ensured.

  Further, in the pneumatic tire 1, the average gauge Ga_in_si of the inner liner 18 in one side wall portion (in the vehicle width direction in FIG. 1) and the other side wall portion (in the vehicle width direction outer side in FIG. 1). The average gauge Ga_out_si of the inner liner 18 has a relationship of Ga_in_si <Ga_out_si. Thereby, there exists an advantage which can form the rigidity difference of a tire right and left effectively.

  In the pneumatic tire 1, the gauge D_in of the inner liner 18 at one end in the tire width direction of the outer cross belt 142 (in the vehicle width direction in FIG. 1) and the other (in the vehicle width direction in FIG. 1). The gauge D_out of the inner liner 18 at the end on the outer side has a relationship of 1.5 ≦ D_out / D_in ≦ 5.0. Accordingly, there is an advantage that the gauge ratio D_out / D_in of the inner liner 18 at the left and right end portions of the outer cross belt 142 is optimized. That is, when 1.5 ≦ D_out / D_in, a difference in rigidity between the left and right tires is effectively ensured, and when D_out / D_in ≦ 5.0, an excessive increase in tire weight is suppressed.

  FIG. 7 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  In this performance test, evaluations on (1) tire weight, (2) noise performance, and (3) steering stability performance were performed on a plurality of different pneumatic tires (see FIG. 6). In this performance test, a pneumatic tire having a tire size of 195 / 65R15 is assembled to an applicable rim specified by JATMA, and an air pressure of 220 [kPa] and a maximum load specified by JATMA are applied to the pneumatic tire. The pneumatic tire is mounted on a front-engine rear-drive (FR) vehicle having a displacement of 2300 [cc], which is a test vehicle.

  (1) The tire weight is evaluated by index evaluation using the conventional example as a standard (100), and the larger the value, the lighter the tire. In this evaluation, if the numerical value is 95 or more, it can be said that the tire weight is within the allowable range.

  (2) In the evaluation regarding noise performance, the test vehicle travels on a test course having a rough road surface at 60 [km / h], and the sound pressure level is measured by a microphone attached to the window side position of the driver's seat. Then, index evaluation using the conventional example as a reference (100) is performed. In this evaluation, the smaller the numerical value, the lower the sound pressure level, which is preferable.

  (3) For the evaluation regarding the steering stability performance, the test vehicle travels on a test course having a flat circuit around 60 [km / h] to 100 [km / h]. The test driver then performs sensory evaluation on the steering performance during cornering. This evaluation is performed by index evaluation using the conventional example as a reference (100), and the larger the value, the better.

  The pneumatic tire 1 of Example 1 has the structure described in FIGS. 1 and 2. Further, as shown in FIG. 2, the rubber sheet of the tread portion constituting the inner liner 18 has a configuration in which the gauge is gradually increased from the inner region in the vehicle width direction toward the outer region in the vehicle width direction. The pneumatic tire 1 of Examples 2-9 is a modification of the pneumatic tire of Example 1.

  In the conventional pneumatic tire 1, the inner liner 18 has a uniform gauge in the configuration of FIG. 1.

  As shown in the test results, it can be seen that in the pneumatic tires 1 of Examples 1 to 9, the steering stability performance can be improved while maintaining the tire weight and the tire noise performance.

  1: Pneumatic tire, 11: Bead core, 12: Bead filler, 13: Carcass layer, 14: Belt layer, 141: Inner cross belt, 142: Outer cross belt, 143: Belt cover, 15: Tread rubber, 16: Side wall Rubber, 17: Rim cushion rubber, 18: Inner liner

Claims (9)

A pneumatic tire comprising a carcass layer, a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and an inner liner disposed on a tire inner peripheral surface,
The average gauge Ga_in of the inner liner in the region from the tire equator plane to one bead toe and the average gauge Ga_out of the inner liner in the region from the tire equator plane to the other bead toe have a relationship of Ga_in <Ga_out. A featured pneumatic tire.   The pneumatic tire according to claim 1, wherein the pneumatic tire has a designation of a mounting direction to be mounted on the vehicle with a side having the average gauge Ga_in being inward in the vehicle width direction.   The pneumatic tire according to claim 1 or 2, wherein the inner liner is made of a thermoplastic resin containing a rubber composition.   The pneumatic tire according to claim 1, wherein average gauges Ga_in and Ga_out of the inner liner have a relationship of 0.05 [mm] ≦ Ga_out−Ga_in ≦ 0.19 [mm]. When the belt layer has a pair of cross belts and the cross belt on the outer side in the tire radial direction of the pair of cross belts is called an outer cross belt,
The average gauge Ga_in_be of the inner liner in one area bounded by the tire equatorial plane in the arrangement area of the outer cross belt and the average gauge Ga_out_be of the inner liner in the other area have a relationship of Ga_in_be <Ga_out_be. The pneumatic tire according to any one of claims 1 to 4. When the belt layer has a pair of cross belts and the cross belt on the outer side in the tire radial direction of the pair of cross belts is called an outer cross belt,
The pneumatic tire according to any one of claims 1 to 5, wherein the gauge of the inner liner gradually increases from one side in the tire width direction toward the other in the arrangement region of the outer cross belt.   The average gauge Ga_in_si of the inner liner in one sidewall portion and the average gauge Ga_out_si of the inner liner in the other sidewall portion have a relationship of 0 ≦ | Ga_out_si−Ga_in_si | ≦ 0.19 [mm]. The pneumatic tire according to any one of Items 1 to 6.   The pneumatic tire according to claim 6, wherein an average gauge Ga_in_si of the inner liner in one sidewall portion and an average gauge Ga_out_si of the inner liner in the other sidewall portion have a relationship of Ga_in_si <Ga_out_si. When the belt layer has a pair of cross belts and the cross belt on the outer side in the tire radial direction of the pair of cross belts is called an outer cross belt,
The gauge D_in of the inner liner at one end in the tire width direction of the outer cross belt and the gauge D_out of the inner liner at the other end have a relationship of 1.5 ≦ D_out / D_in ≦ 5.0. The pneumatic tire according to any one of claims 1 to 8.

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