JP2016074359A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire having a structure in which a carcass ply is wound inward from outside in a tire width direction, which suppresses extension of a wound part of the carcass ply so as to improve durability.SOLUTION: The pneumatic tire comprises: a pair of left and right beads 30 including a bead core 31 and a bead filler 32 provided near an outer periphery of the bead core 31; a carcass ply 4 bridged across the pair of beads 30; and an inner liner 5 arranged near an inner periphery of the carcass ply 4. The carcass ply 4 comprises a ply winding part 42 that is wound around the bead core 31 from outside in a tire width direction toward inside in the tire width direction, and arranged inside in the tire width direction of the beads 30. The inner liner 5 comprises a liner end part 51 arranged further inside in the tire width direction than the beads 30, and a reinforcing layer 7 formed of a fiber material coated with rubber is arranged between the ply winding part 42 and the liner end part 51.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  In a pneumatic tire, a carcass ply as a reinforcing material embedded therein is generally configured to wind up from the inner side in the tire width direction to the outer side so as to wrap the bead core. On the other hand, Patent Documents 1 to 3 propose a configuration in which the carcass ply is wound from the outside in the tire width direction to the inside. By rolling up the carcass ply from the outer side in the tire width direction in this way, the distribution of the tension applied to the carcass ply is changed, the tension at a position that tends to contribute to the tire rigidity is increased, and the steering stability performance is improved.

JP 2007-131173 A JP 2002-513360 Gazette JP 7-315013 A JP 2002-144825 A

  Such a configuration in which the carcass ply is wound from the outer side to the inner side in the tire width direction is advantageous in terms of steering stability, but the carcass ply hoisting portion tends to expand and contract due to stress concentration, leading to the occurrence of separation. Durability may be impaired.

  The pneumatic tire shown in Patent Document 4 relates to a tire having a structure in which a carcass ply is wound around the bead core from the inner side to the outer side in the tire width direction, and the expansion and contraction of the winding part of the carcass ply is suppressed. Not disclosed.

  In view of the above points, the present invention aims to improve durability by suppressing the expansion and contraction of the winding portion of the carcass ply in a pneumatic tire having a configuration in which the carcass ply is wound inward from the outer side in the tire width direction. And

  A pneumatic tire according to the present invention includes a pair of left and right beads including a bead core and a bead filler provided on an outer peripheral side of the bead core, a carcass ply spanned between the pair of beads, and an inner peripheral side of the carcass ply In the pneumatic tire having an inner liner disposed on the ply, the carcass ply is wound around the bead core from the outer side in the tire width direction to the inner side in the tire width direction, and the ply hoisting portion disposed on the inner side in the tire width direction of the bead The inner liner includes a liner end portion disposed on the inner side in the tire width direction from the bead, and a reinforcing layer formed by covering a fiber material with rubber is interposed between the ply winding portion and the liner end portion. It is arranged.

  In the pneumatic tire of the present invention, the reinforcing layer formed by coating the fiber material with rubber includes a ply winding portion of the carcass ply and a liner end portion disposed on the inner width direction of the inner liner from the ply winding portion. Since it is arrange | positioned between, the expansion-contraction of a ply winding part can be suppressed and durability can be improved.

1 is a half sectional view of a pneumatic tire according to a first embodiment. FIG. 2 is an enlarged cross-sectional view around a bead portion in FIG. 1. It is an expanded sectional view around a bead part of a pneumatic tire concerning a 2nd embodiment.

[First embodiment]
The pneumatic tire T of the embodiment shown in FIG. 1 is a pneumatic radial tire for passenger cars, and includes a tread portion 1 that constitutes a ground contact surface, a pair of left and right bead portions 3, and a tread portion 1 and a bead portion 3. It has a pair of left and right sidewall portions 2 interposed therebetween.

  In the bead portion 3, a bead 30 including an annular bead core 31 and a bead filler 32 joined and integrated with the outer peripheral surface of the bead core 31 is embedded. Therefore, the beads 30 are provided in a pair of left and right in the tire T. The bead core 31 is formed by bundling bead wires into an annular shape. The bead filler 32 is made of hard rubber extending outward in the tire radial direction from the bead core 31 and has a substantially triangular cross-section with a narrower width toward the tip side.

  In the tire T, a carcass ply 4 laid between a pair of beads 30 is embedded. The carcass ply 4 reaches the bead portion 3 from the tread portion 1 through the side wall portions 2 on both sides, and both end portions thereof are wound and locked by the bead core 31. Therefore, the carcass ply 4 includes a toroid-shaped main body portion 41 straddling between the pair of bead cores 31, and a ply winding portion 42 wound around the bead core 31 on both sides of the main body portion 41. The carcass ply 4 is formed by arranging a carcass cord as a reinforcing material in parallel with a predetermined number of driving and covering with a topping rubber, and the carcass cord is arranged so as to be substantially perpendicular to the tire circumferential direction. Has a single-layer structure consisting of a single ply.

  As shown in FIG. 2, the carcass ply 4 is wound up from the outer side in the tire width direction X to the inner side around the bead core 31 through the tire outer surface side of the bead filler 32 at both ends of the carcass ply 4. Has been. The ply winding portion 42 wound up in this way extends outward in the tire radial direction on the inner side in the tire width direction of the bead 30 including the bead core 31 and the bead filler 32. In this example, the tip end (tire radial direction outer end) 43 of the ply winding part 42 extends to the bead filler 32 beyond the tire radial direction outer end (outer peripheral surface of the bead core 31) 31A of the bead core 31. The bead filler 32 terminates in the tire radial direction inner side than the tire radial direction outer end 32A.

  The inside of the carcass ply 4 is made of a topping rubber that covers the ply cord of the carcass ply 4 or a rubber (for example, butyl rubber or halogenated butyl rubber) that is less permeable to gas than the tread rubber 13 described later. An inner liner 5 that functions as an air permeation suppression layer to be held is provided over the entire inner surface of the tire. The inner liner 5 includes liner ends 51 arranged on the inner peripheral side of the beads 30 and the carcass ply 4 at both ends in the tire width direction. For example, the tip of the liner end 51 (inner end in the tire radial direction) 52 terminates at the same position as the tire radial direction inner end (inner circumferential surface of the bead core 31) 31B of the bead core 31 in the tire radial direction.

  A belt 11 is disposed on the outer peripheral side of the carcass ply 4 in the tread portion 1. The belt 11 is composed of one or a plurality of belt layers in which a belt cord is inclined at a constant angle with respect to the tire circumferential direction. In this example, the belt 11 is composed of two belt layers. A tread rubber 13 is provided on the outer peripheral side of the belt 11 through a belt reinforcing layer 12 formed by spirally winding an organic fiber cord. Further, a sidewall rubber 21 is provided on the tire outer surface side of the carcass ply 4 in the sidewall portion 2.

  The bead portion 3 is provided with a rubber chacher 6. The rubber chafer 6 covers a portion where the bead portion 3 comes into contact with the rim when the rim is assembled. Specifically, the rubber chafer 6 is positioned around the bead core 31 on the outer side in the tire width direction and the inner side in the tire radial direction of the bead 30. It arrange | positions so that the carcass ply 4 to cover may be coat | covered.

  In the above configuration, in the present embodiment, as shown in FIG. 2, a fiber material is provided between the ply-up portion 42 of the carcass ply and the liner end portion 51 of the inner liner 5 disposed on the inner side in the tire width direction. A reinforcing layer 7 is provided which is coated with a topping rubber.

  The reinforcing layer 7 is in close contact with the inner liner 5, and the inner end 71 in the tire radial direction of the reinforcing layer 7 is the inner side in the tire width direction of the bead core 31, that is, the tire radial direction from the outer end 31 </ b> A in the tire radial direction of the bead core 31. It is located on the inner side and on the outer side in the tire radial direction from the inner end 31 </ b> B in the tire radial direction of the bead core 31, and extends outward in the tire radial direction along the ply winding portion 42.

  The inner end 71 in the tire radial direction of the reinforcing layer 7 is disposed at a position away from the inner end 31B in the tire radial direction of the bead core 31 by a length H1 in the tire radial direction. The reinforcing layer 7 has a tire diameter of the reinforcing layer 7 from the tire radial inner end 31B of the bead core 31 as compared to the length H2 in the tire radial direction from the tire radial inner end 31B of the bead core 31 to the tip 43 of the ply winding portion 42. The tire radial direction length H3 to the direction outer end 72 is set large, and extends beyond the tip 43 of the ply-winding portion 42 to the bead filler 32.

  In this way, the reinforcing layer 7 extends from the inner side in the tire width direction of the bead core 31 to the outer side in the tire radial direction from the tip 43 of the ply winding part 42 along the ply winding part 42. The reinforcing layer 7 is disposed so as to straddle, which is preferable in that separation at the tip 43 of the ply-winding portion 42 can be more effectively prevented.

  The outer end 72 in the tire radial direction of the reinforcing layer 7 terminates on the inner side in the tire radial direction from the outer end 32A in the tire radial direction of the bead filler 32, and the tire radial direction of the reinforcing layer 7 from the inner end 31B in the tire radial direction of the bead core 31. The tire radial length H3 to the outer end 72 is preferably 90% or less of the tire radial length H4 from the tire radial inner end 31B of the bead core 31 to the tire radial outer end 32A of the bead filler 32. By setting the length H3 to 90% or less of the length H4 in this way, the tire radial direction outer end 72 of the reinforcing layer 7 can be spaced apart from the tire radial direction outer end 32A of the bead filler 32. This is preferable because a sudden change in rigidity can be eliminated and the occurrence of separation at the outer end 32A in the tire radial direction of the bead filler 32 can be prevented.

  Further, a ratio R (= H2−H1) of a tire radial direction length H5 (= H2−H1) of a region where the reinforcing layer 7 overlaps the ply winding portion 42 with respect to the tire radial length H6 (= H3−H1) of the reinforcing layer 7 (= H5 / H6) is preferably 20% or more and 80% or less.

  When the ratio R is 20% or more, expansion and contraction of the ply-winding portion can be more effectively suppressed, and durability can be improved. Further, when the ratio R is 80% or less, the outer end 72 in the radial direction of the tire of the reinforcing layer 7 can be spaced apart from the tip 43 of the ply-winding portion 42, so that a sudden change in rigidity can be eliminated. This is preferable because separation at the tip 43 of the ply-winding portion 42 can be prevented.

  In addition, each said dimension value in this embodiment is a thing in the no-load normal state which mounted | wore the normal rim and filled the normal internal pressure. A regular rim is a rim determined for each tire in a standard system including a standard on which a tire is based. For example, a standard rim for JATMA, a “Design Rim” for TRA, or a rim for ETRTO. "Measuring Rim". In addition, the normal internal pressure is the air pressure defined by each standard for each tire in the standard system. If it is JATMA, it is the maximum air pressure, and if it is TRA, it is described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" If the maximum value is ETRTO, "INFLATION PRESSURE" is assumed.

  In this embodiment, a rubber-nonwoven fabric composite in which a nonwoven fabric is coated with a rubber material is used as the reinforcing layer 7.

  The material of the nonwoven fabric used for the reinforcing layer 7 is not particularly limited. For example, polyester fibers, aliphatic polyamide fibers (nylon fibers), aromatic polyamide fibers (aramid fibers), polyvinyl alcohol fibers, organic fibers such as carbon fibers, Examples thereof include inorganic fibers such as metal fibers and glass fibers, and may be short fibers or long fibers. Preferably, it is an organic fiber from a viewpoint of weight reduction.

  Moreover, the manufacturing method of a nonwoven fabric is not specifically limited, For example, the method of forming a web by a dry method, a wet method, a spun bond method, a melt blow method, an airlaid method etc. is mentioned. Examples of the fiber bonding method for the web include a chemical bond method, a thermal bond method, a needle punch method, and a hydroentanglement method.

  The rubber-nonwoven fabric composite preferably has a 5% elongation stress at the unvulcanized stage of 5.0 MPa or more. When the stress at 5% elongation is 5.0 MPa or more, the effect of improving the steering stability can be enhanced. The stress at 5% elongation is more preferably 7.0 MPa or more. The upper limit of the stress at 5% elongation is not particularly limited, but is usually 10.0 MPa or less.

The basis weight (mass per unit area) of the rubber-nonwoven fabric composite is preferably 50 to 300 g / m ² . When the basis weight is 50 g / m ² or more, a decrease in stress at 5% elongation can be suppressed. Moreover, the influence on tire mass can be suppressed by being 300 g / m < ² > or less. The basis weight of the nonwoven fabric itself (the basis weight of the nonwoven fabric before applying the rubber material) may be, for example, 10 to 100 g / m ² or 20 to 60 g / m ² . Moreover, the adhesion amount per unit area of the rubber composition may be, for example, 10 to 300 g / m ² or 15 to 250 g / m ² .

  The thickness of the rubber-nonwoven fabric composite is preferably, for example, 0.10 to 0.50 mm, and more preferably 0.15 to 0.40 mm.

  The rubber material for covering the nonwoven fabric is made of a topping rubber for covering the ply cord of the carcass ply 4 such as butyl rubber or halogenated butyl rubber, or a rubber that is less gas permeable than the tread rubber 13, and preferably constitutes the inner liner 5. It is made of the same rubber material as the rubber material to be processed. Thus, by using the same rubber material as the rubber material constituting the inner liner 5 as the rubber material constituting the reinforcing layer 7, the adhesion between the reinforcing layer 7 and the inner liner 5 is improved, and the bead portion 3 Gas permeation resistance can be improved.

  In the present embodiment, the case where a rubber-nonwoven fabric composite in which a nonwoven fabric is coated with a rubber material is used for the reinforcing layer 7 has been described. However, the present invention is not limited to this. A material coated with a material may be used for the reinforcing layer 7.

  In this embodiment, since the reinforcing layer 7 formed by covering the fiber material with rubber is disposed between the ply winding portion 42 and the liner end portion 51, the expansion and contraction in the vicinity of the ply winding portion 42 where stress is likely to concentrate is provided. It can be suppressed and durability can be improved.

  In this embodiment, since the reinforcing layer 7 is provided in close contact with the inner liner 5, a pneumatic tire is formed using the inner liner 5 in which the reinforcing layers 7 are attached to both ends in the tire width direction in advance. Thus, the reinforcing layer 7 can be easily disposed between the ply winding portion 42 and the liner end portion 51.

  Further, in the present embodiment, since the inner end 71 in the tire radial direction of the reinforcing layer 7 is disposed outward in the tire radial direction from the inner end 31B in the tire radial direction of the bead core 31, the bead portion 3 is not easily displaced from the rim. The occurrence of air leaks can be suppressed.

[Second Embodiment]
FIG. 3 is an enlarged cross-sectional view around the bead portion of the pneumatic tire according to the second embodiment.

  In the second embodiment, both end portions in the tire width direction of the inner liner 5 are arranged along the tire width direction inner side of the bead 30 between the bead 30 and the carcass ply 4 in the bead portion 3, and around the bead core 31. Is wound up from the inside in the tire width direction X to the outside. Accordingly, both end portions in the tire width direction of the inner liner 5 are provided with liner end portions 51 disposed between the bead 30 and the carcass ply 4.

The winding height of the liner winding portion 53 of the inner liner 5 is not particularly limited. In this example, the winding portion 53 terminates in the vicinity of the outer end 31 </ b> A of the bead core 31 in the tire radial direction. It may be terminated beyond the outer end 31A, or may be terminated at the inner side in the tire radial direction than the outer end 31A in the tire radial direction of the bead core 31.
The bead portion 3 is provided with a rubber chacher 6. The rubber chafer 6 is arranged around the bead core 31 so as to cover the carcass ply 4 and the inner liner 5.

  And, between the liner end portion 51 arranged on the inner side of the bead 30 in the tire width direction and the ply winding portion 42 of the carcass ply 4 in the inner liner 5, a reinforcing layer 7 is formed by covering the fiber material with a topping rubber. Is provided.

  According to the present embodiment, since both end portions of the inner liner 5 are disposed between the bead core 31 and the carcass ply 4, the bead core 31 and the carcass ply 4 are not in direct contact. Therefore, it is possible to prevent breakage caused by rubbing the bead core 31 and the carcass ply 4 in direct contact with each other when a high tension state is reached. Other configurations and effects are the same as those in the first embodiment, and a description thereof will be omitted.

  Although some embodiments have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. The performance evaluation of the tire was performed as follows. In addition, this invention is not limited by these Examples.

-Durability (Failure occurrence distance at the ply winding part)
In accordance with the conditions defined in the US automobile safety standard FMVSS 139 as an endurance test, a drum tester made of steel having a smooth surface and a diameter of 1700 mm was used. As the test tire, a tire of size 195 / 65R15 91H and rim size 15 × 6.0 is used, the tire internal pressure is 220 kPa, the speed is 120 km / h, the load is based on the maximum load specified by JATMA, and the load is 85%. The load was reduced to 4 hours, 90% load for 6 hours, 100% load for 24 hours, and the air pressure to 160 kPa for 1.5 hours at 100% load. Thereafter, the vehicle was run for 6 hours at a speed of 81 km / h, an internal pressure of 220 kPa, and a load of 120%. Thereafter, the load was set to 140%, and the vehicle was run until a failure occurred at the ply-winding portion. The distance traveled until the failure occurred was indexed with the tire of Comparative Example 1 as 100. The larger the number is, the longer the distance until a failure occurs at the ply-winding portion, and the better the durability.

(Examples 1-4)
In Examples 1 to 4, the reinforcing layer 7 is disposed between the ply winding portion 42 of the carcass ply 4 and the liner end portion 51 of the inner liner 5 disposed on the inner side in the tire width direction of the ply winding portion 42. 2 is a tire radial length from the tire radial inner end 31B of the bead core 31 to the tip 43 of the ply winding portion 42 in the tire radial direction, and the tire of the bead filler 32 from the tire radial inner end 31B of the bead core 31. The configuration other than the reinforcing layer 7 such as the tire radial direction length H4 up to the radial outer end 32A is the same, the length H1 in the tire radial direction from the tire radial inner end 31B of the bead core 31, and the tire radial direction of the bead core 31 The tire radial direction length H3 from the inner end 31B to the tire radial direction outer end 72 of the reinforcing layer 7 is changed as shown in Table 1 and manufactured.

(Comparative Example 1)
Comparative Example 1 is a tire manufactured in the same manner as in Example 1 except that the reinforcing layer 7 is not disposed between the ply winding portion 42 of the carcass ply 4 and the liner end portion 51 of the inner liner 5.

  The results are as shown in Table 1, and in Examples 1 to 4, the distance until failure occurred in the ply-winding portion was longer than that in Comparative Example 1, and excellent in durability. Further, in the embodiment, the outer end 72 in the tire radial direction of the reinforcing layer 7 extends to the outside of the tip 43 of the ply-winding portion 42 as compared with the first embodiment in which the outer end 72 in the tire radial direction is positioned inward in the tire radial direction from the tip 43 of the ply-winding portion 42 In Nos. 2 to 4, the distance until a failure occurred at the ply-winding portion was longer and the durability was further improved.

T ... tyre 1 ... tread part 2 ... side wall part 3 ... bead part 4 ... carcass ply 5 ... inner liner 6 ... rubber chaher 7 ... reinforcing layer 30 ... bead 31 ... bead core 31A ... diameter outer end 31B of the bead core ... The inner end 32 of the bead core in the tire radial direction 32 ... The outer end of the bead filler 32A in the radial direction of the tire 41 ... The main body 42 ... The ply hoisting portion 43 ... The tip 51 of the ply hoisting portion 51 ... The liner end 52 ... The tip 71 of the inner liner ... Tire radial direction inner end 72 ... tire radial direction outer end of the reinforcing layer

Claims (7)

Air having a pair of left and right beads including a bead core and a bead filler provided on the outer peripheral side of the bead core, a carcass ply spanned between the pair of beads, and an inner liner disposed on the inner peripheral side of the carcass ply In entering tires,
The carcass ply is wound around the bead core from the outer side in the tire width direction to the inner side in the tire width direction, and includes a ply hoisting portion disposed on the inner side in the tire width direction of the bead.
The inner liner includes a liner end disposed on the inner side in the tire width direction from the bead,
A pneumatic tire in which a reinforcing layer formed by covering a fiber material with rubber is disposed between the ply-winding portion and the liner end portion.   The pneumatic tire according to claim 1, wherein the reinforcing layer is disposed in close contact with the inner liner.   The pneumatic tire according to claim 1 or 2, wherein a rubber material that covers the fiber material in the reinforcing layer has lower gas permeability than a rubber material that covers a ply cord in the carcass ply.   The tire radial length from the tire radial inner end of the bead core to the tire radial outer end of the reinforcing layer is the tire radial length from the tire radial inner end of the bead core to the tire radial outer end of the bead filler. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is 90% or less.   The pneumatic tire according to any one of claims 1 to 4, wherein an inner end in the tire radial direction of the reinforcing layer is disposed outward in the tire radial direction from an inner end in the tire radial direction of the bead core.   The length in the tire radial direction of the region where the reinforcing layer overlaps with the ply winding-up portion is 20% or more and 80% or less of the length of the reinforcing layer in the tire radial direction. The described pneumatic tire.   The pneumatic tire according to any one of claims 1 to 5, wherein an outer end in the tire radial direction of the reinforcing layer is disposed outward in the tire radial direction from the outer end in the tire radial direction of the ply-up portion.

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