JP2016068821A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire comprising a chafer around a bead, in which a periphery of a bead part has good durability.SOLUTION: The pneumatic tire comprises: a chafer 3 that is folded back, outside folded parts of carcass plies 2a, from inside to outside in a tire width direction and wound up to outside in a tire radial direction; a rim strip 6 that is provided across a position more outer in a tire width direction than a wound-up part 30 of the chafer 3 and a position more outer in the tire radial direction than the wound-up part 30; and a sidewall rubber 43 provided more outward in the tire radial direction than the rim strip 6. A reinforcement sheet 5 that is lower in hardness than the rim strip 6 and higher in hardness than the sidewall rubber 43 is provided from a position between wound-up parts of the carcass plies 2a and the wound-up part 30 of the chafer 3 to a position more outer in the tire radial direction than a boundary between the rim strip 6 and the sidewall rubber 43.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pneumatic tire.

  A carcass ply of a pneumatic tire is folded back from the inner side in the tire width direction to the outer side around the bead and wound up outward in the tire radial direction. In some cases, the chacher (chafer) is folded from the inner side in the tire width direction to the outer side and wound up toward the outer side in the tire radial direction on the outside of the carcass ply turn (see, for example, Patent Document 1). In this case, the winding portion of the carcass ply and the winding portion of the chacher are in contact with each other.

JP2013-147065A

  In the above pneumatic tire, if the chacher is greatly distorted or small distortions repeatedly occur, the carcass ply hoisting part and the chaher hoisting part may rub against each other and separation may occur from the end of the chaher hoisting part. is there.

  Therefore, an object of the present invention is to provide a pneumatic tire including a chacher around a bead and having good durability around the bead portion in which separation from the end portion of the hoisted portion of the chaher is unlikely to occur.

  The pneumatic tire according to the embodiment includes a bead portion, a carcass ply that is folded from the inner side to the outer side in the tire width direction around the bead portion and wound outward in the tire radial direction, and the tire width at the outer side of the folded back of the carcass ply. A chafer that is folded from the inner side to the outer side and wound outward in the radial direction of the tire, and is arranged from a position on the outer side in the tire width direction from the hoisting portion of the chacher to a position on the outer side in the tire radial direction from the end of the hoisting portion of the chaher A rim strip and a sidewall rubber provided on the outer side in the tire radial direction from the rim strip, and a reinforcing sheet having a hardness lower than that of the rim strip and higher than that of the sidewall rubber, and a winding portion of the carcass ply From the position between the winding part of the chacher, Wherein the Tsu than boundary flop and said sidewall rubber is disposed over the position of the outer side in the tire radial direction.

  In the pneumatic tire according to the embodiment, separation from the end portion of the rolled-up portion of the chacher hardly occurs, and durability around the bead portion is good.

The half sectional view of the pneumatic tire of an embodiment.

  As shown in FIG. 1, the pneumatic tire according to the embodiment includes a bead portion 1 including a bead core 10 and a bead filler 11 provided on the outer side in the tire radial direction. Further, the carcass ply is folded around the bead portion 1 from the inner side in the tire width direction to the outer side and wound up outward in the tire radial direction. In the illustrated embodiment, as the carcass ply, a carcass ply 2a that is on the outer side in the tire width direction and a carcass ply 2b that is on the inner side are provided at the folded portion. However, one carcass ply may be used. A belt 40, a reinforcing layer 41, and a tread 42 are provided on the outer side in the tire radial direction from the carcass plies 2a and 2b. Side wall rubber 43 is provided on the outer side in the tire width direction from the carcass plies 2a, 2b.

  A chacher 3 is provided on the outer side of the turn of the carcass plies 2a, 2b. Specifically, the chacher 3 is provided on the inner side in the tire width direction from the bead portion 1 and on the inner side in the tire width direction from the carcass plies 2a and 2b, and to the outer side in the tire width direction around the bead core 10 like the carcass plies 2a and 2b. It is turned up and is wound up outward in the tire radial direction from the wind-up part of the carcass plies 2a, 2b on the outer side in the tire width direction. This portion that has been wound up is referred to as a winding portion 30 of the chacher 3. The chacher 3 is generally a fiber cord covered with rubber, but a steel cord covered with rubber may be used. Some of the chachers 3 are not embedded with cords. The chacher 3 is in contact with the carcass ply 2 a in the vicinity of the bead core 10. However, the winding portion 30 of the chacher 3 is separated from the winding portion 20a of the carcass ply 2a on the outer side in the tire radial direction from a certain portion.

  A rubber rim strip 6 is provided on the outer side in the tire width direction from the winding portion 30 of the chacher 3. The rim strip 6 extends to the outer side in the tire radial direction from the end of the winding portion 30 of the chacher 3. The portion on the outer side in the tire radial direction of the rim strip 6 is in contact with the portion on the inner side in the tire radial direction of the sidewall rubber 43. The rim strip 6 is harder than the sidewall rubber 43.

  The reinforcing sheet 5 is sandwiched between the winding portion 20a of the carcass ply 2a and the winding portion 30 of the chacher 3. The reinforcing sheet 5 extends toward the outer side in the tire radial direction along the winding portion 20a of the carcass ply 2a, and the end portion on the outer side in the tire radial direction is closer to the tire radial direction than the boundary between the rim strip 6 and the sidewall rubber 43. On the outside. Accordingly, the reinforcing sheet 5 is sandwiched between the winding portion 20a of the carcass ply 2a and the winding portion 30 of the chacher 3 on the inner side in the tire radial direction, and between the winding portion 20a of the carcass ply 2a and the sidewall rubber 43 on the outer side in the tire radial direction. In between these, it is sandwiched between the winding portion 20a of the carcass ply 2a and the rim strip 6. The reinforcing sheet 5 is a sheet-like rubber member, but may be reinforced with a cord such as a fiber. When the reinforcing sheet 5 is reinforced with fiber cords, the fibers are preferably organic fibers such as aramid, polyester, nylon, and rayon.

  The range in which the reinforcing sheet 5 is provided is as follows in more detail.

  The end of the reinforcing sheet 5 on the outer side in the tire radial direction is desirably located on the inner side in the tire radial direction with respect to the position of the maximum width of the tire. In the case of the embodiment of FIG. 1, the end of the reinforcing sheet 5 on the outer side in the tire radial direction is on the outer side in the tire radial direction with respect to the bead filler 11, and is on the inner side in the tire radial direction with respect to the end of the carcass ply 2 a. . The distance p in the tire radial direction from the end in the tire radial direction of the rim strip 6 to the end in the tire radial direction of the reinforcing sheet 5 is the end of the belt 40 from the end in the tire radial direction of the rim strip 6. It is desirable that it is 3% to 40% of the distance q in the tire radial direction to the end of the belt that is widest in the tire width direction when there are a plurality of belts.

  The distance m in the tire radial direction from the end of the bead core 10 in the tire radial direction to the end of the reinforcing sheet 5 in the tire radial direction is the rolled-up portion of the chafer 3 from the end of the bead core 10 in the tire radial direction. The distance n in the tire radial direction to the end of 30 is preferably 0% or more and 50% or less.

  Here, the hardness of the rubber of the reinforcing sheet 5 is lower than the hardness of the rim strip 6 and higher than the hardness of the sidewall rubber 43. The hardness is a hardness measured based on JIS K 6253. For example, the hardness of the rim strip 6 is 65 or more and 75 or less, the hardness of the rubber of the reinforcing sheet 5 is 60 or more and 70 or less, and the hardness of the sidewall rubber 43 is 50 or more and 60 or less.

  In general, the modulus of the rim strip 6 is larger than the modulus of the sidewall rubber 43, but it is desirable that the modulus of the rubber of the reinforcing sheet 5 is larger than the modulus of the rim strip 6. That is, it is desirable that the modulus of rubber is larger in the order of the reinforcing sheet 5, the rim strip 6, and the sidewall rubber 43. The modulus is a 300% modulus measured based on JIS K 6251. For example, the modulus of rubber of the reinforcing sheet 5 is 10.0 MPa or more and 20.0 MPa or less, the modulus of the rim strip 6 is 12.0 MPa or more and 15.0 MPa or less, and the modulus of the sidewall rubber 43 is 5.0 MPa or more and 8.0 MPa or less. is there.

  Further, it is desirable that a value (modulus (MPa)) / (hardness) obtained by dividing the modulus value of the reinforcing sheet 5 by the hardness value is 0.10 or more and 0.40 or less.

  In addition, the position of each member and the edge part in the above description is a no-load thing at the time of mounting a pneumatic tire on a regular rim and setting it as a regular internal pressure. Here, the regular rim is “standard rim” in the JATMA standard, “Design Rim” in the TRA standard, or “Measuring Rim” in the ETRTO standard. The normal internal pressure is “maximum air pressure” in JATMA standard, “maximum value” described in “TIRE LOAD LIMITATIONS AT VARIOUS COLD INFRATION PRESURES” in TRA standard, or “INFLATION PRESSURE” in ETRTO standard.

  In the pneumatic tire having the above structure, the reinforcing sheet 5 is sandwiched between the winding portion 20a of the carcass ply 2a and the winding portion 30 of the chacher 3, so that the winding portion 20a of the carcass ply 2a and the winding portion 30 of the chacher 3 are disposed. Rub is suppressed. Therefore, there is little possibility that separation will occur from the end of the winding part 30 of the chacher 3. Further, since the hardness of the reinforcing sheet 5 is higher than the hardness of the sidewall rubber 43, it is possible to prevent the hoisting portion 30 of the chacher 3 from moving, and the hoisting portion 30 of the chacher 3 repeatedly moves and generates heat near its end portion. It is possible to prevent the distortion from concentrating on the end portion and causing separation from the starting point. On the other hand, since the hardness of the reinforcing sheet 5 is lower than the hardness of the rim strip 6, the hardness difference between the reinforcing sheet 5 and the sidewall rubber 43 does not become too large. Therefore, separation between the reinforcing sheet 5 and the side wall rubber 43 hardly occurs. For these reasons, the pneumatic tire having the above structure has good durability around the bead portion 1.

  Further, since the hardness of the reinforcing sheet 5 is higher than the hardness of the sidewall rubber 43, the reinforcing sheet 5 plays a role of reinforcing both sides in the tire width direction.

  Moreover, when the modulus of rubber is larger in the order of the reinforcing sheet 5, the rim strip 6, and the sidewall rubber 43, the durability around the bead portion 1 is further improved. Specifically, when the modulus of the reinforcing sheet 5 is the largest among the three, the winding portion 30 of the chacher 3 is difficult to move with respect to the winding portion 20a of the carcass ply 2a, so that the durability around the bead portion 1 is good. . Further, since the modulus of the rim strip 6 is smaller than that of the reinforcing sheet 5, and therefore the difference in modulus between the rim strip 6 and the sidewall rubber 43 is small, separation hardly occurs at the boundary between the rim strip 6 and the sidewall rubber 43. .

  Further, when the value of (modulus) / (hardness) of the reinforcing sheet 5 is 0.10 or more and 0.40 or less, the balance between the modulus and the hardness is the best. Further, when the value of (modulus) / (hardness) of the reinforcing sheet 5 is within this range, the modulus or hardness of the reinforcing sheet 5 is less likely to be extremely large or extremely small. There is little risk of separation between the members.

  In addition, the distance p in the tire radial direction from the end portion on the outer side in the tire radial direction of the rim strip 6 to the end portion on the outer side in the tire radial direction of the reinforcing sheet 5 is the distance from the end portion on the outer side in the tire radial direction of the rim strip 6. When the distance q in the tire radial direction to the end is 3% or more and 40% or less, both the durability around the bead portion 1 and the good riding comfort of the pneumatic tire are compatible. Specifically, if the distance p is 3% or more of the distance q, the end portion on the outer side in the tire radial direction of the reinforcing sheet 5 is far away from the contact surface between the rim strip 6 and the sidewall rubber 43. Therefore, separation at the contact surface is difficult to occur, and durability around the bead portion 1 is good. If the distance p is 40% or less of the distance q, the portion where the reinforcing sheet 5 inside the sidewall rubber 43 is not disposed is wide, so that the pneumatic tire can be bent and Tire comfort is good.

  The distance m in the tire radial direction from the end of the bead core 10 in the tire radial direction to the end of the reinforcing sheet 5 in the tire radial direction is determined from the end of the bead core 10 in the tire radial direction from the end in the tire radial direction. If the distance n in the tire radial direction to 30 ends is 0% or more and 50% or less, the uniformity of the pneumatic tire and the durability around the bead portion 1 are compatible. Specifically, if the distance m is 0% or more of the distance n, that is, if the reinforcing sheet 5 is not on the inner side in the tire radial direction from the end portion on the outer side in the tire radial direction of the bead core 10, the reinforcing sheet 5 is the tire uniformity. There is little possibility of worsening the rim assembly or rim assembly. Further, if the distance m is 50% or less of the distance n, the reinforcing sheet 5 having a sufficient area is sandwiched between the winding portion 20a of the carcass ply 2a and the winding portion 30 of the chacher 3, so Good durability.

  The durability of the pneumatic tires of Comparative Examples and Examples was examined.

  The pneumatic tire of Example 1 has the characteristics of the pneumatic tire of the above embodiment. On the other hand, the reinforcing sheet is not provided in the pneumatic tire of Comparative Example 1. The pneumatic tire of Comparative Example 2 is provided with a reinforcing sheet, but the rubber hardness of the reinforcing sheet is higher than the hardness of the rim strip and sidewall rubber. The detailed structure of each pneumatic tire is shown in Table 1.

  The durability was examined by an LT step load endurance test based on FMVSS119. The result of the investigation was expressed as an index in which the value of Comparative Example 1 was 100, and the value increased as the running distance until the tire broke down was longer and the durability was better.

  The riding comfort was evaluated by sensory driving with tires attached to the vehicle. The evaluation result was expressed as an index in which the value of Comparative Example 1 was 100 and the value increased as the riding comfort improved.

  The size of the tire to be evaluated is 215 / 65R16C.

  The results are as shown in Table 1, and it was confirmed that the durability and riding comfort of the pneumatic tire of Example 1 were better than those of the comparative example.

DESCRIPTION OF SYMBOLS 1 ... Bead part, 10 ... Bead core, 11 ... Bead filler, 2a, 2b ... Carcass ply, 20a ... Winding part of carcass ply 2a, 3 ... Chaher, 30 ... Winding part of chaher 3, 40 ... Belt, 41 ... Reinforcement layer 42 ... tread, 43 ... sidewall rubber, 5 ... reinforcing sheet, 6 ... rim strip

Claims (5)

A bead portion, a carcass ply that is folded from the inner side to the outer side in the tire width direction around the bead portion and wound up to the outer side in the tire radial direction, and is folded from the inner side to the outer side in the tire width direction at the outer side of the folding of the carcass ply. A chager wound up outward in the tire radial direction, a rim strip disposed from a position outside in the tire width direction from the hoisted portion of the chacher to an end in the tire radial direction from an end of the hoisted portion of the chacher, and the rim strip With sidewall rubber provided on the outer side in the tire radial direction,
A reinforcing sheet having a hardness lower than that of the rim strip and higher than that of the sidewall rubber is determined from a boundary between the rim strip and the sidewall rubber from a position between the winding portion of the carcass ply and the winding portion of the chacher. A pneumatic tire characterized by being arranged over a position radially outside the tire.   The pneumatic tire according to claim 1, wherein the modulus is larger in the order of the reinforcing sheet, the rim strip, and the sidewall rubber.   The pneumatic tire according to claim 1 or 2, wherein a value of (modulus) / (hardness) of the reinforcing sheet is 0.10 or more and 0.40 or less. A belt is provided on the outer side in the tire radial direction of the carcass ply,
The distance in the tire radial direction from the tire radial outer end of the rim strip to the tire radial outer end of the reinforcing sheet is from the tire radial outer end of the rim strip to the belt end. The pneumatic tire according to any one of claims 1 to 3, which is 3% to 40% of the distance in the tire radial direction.   The distance in the tire radial direction from the end portion in the tire radial direction of the bead core of the bead portion to the end portion in the tire radial direction of the reinforcing sheet is the winding portion of the chafer from the end portion in the tire radial direction of the bead core. The pneumatic tire according to any one of claims 1 to 4, which is 0% or more and 50% or less of a distance in a tire radial direction to the end of the tire.

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