JP2006199223A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving the driving stability while the loaded durability is maintained at the same level as conventional. <P>SOLUTION: The pneumatic tire is structured so that bead cores 6 are embedded in a left and a right bead part 3 and a bead filler 7 extending to side wall 2 is provided on the periphery of each bead core 6. Between the left and right bead parts 3, two carcass layers 4 and 5 are laid extending, and a plurality of belt layers 8 and 9 are laid on the peripheries of the carcass layers 4 and 5 of the tread part 2. In the side region R between the two carcass layers 4 and 5 of each side wall part 2 and outside in the tire radial direction more than the external edge 7a of the bead filler 7, a rubber sheet layer 11 consisting of rubber having a 50% modulus of 0.5-10 MPa is laid ring-shapedly in the tire circumferential direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire capable of improving steering stability while maintaining load durability at the same level as that of a conventional tire.

  In recent years, with higher performance of automobiles, higher steering stability is required for pneumatic tires. Therefore, there is a method of increasing the rigidity of the sidewall portion by extending an existing member, for example, a hard bead filler to the outside in the tire radial direction, and improving the steering stability, but the tire cross-section height is 100 mm or less. In such a flat tire, there arises a problem that load durability is greatly deteriorated.

In addition, there is a method of newly arranging a reinforcing member in the sidewall portion (see, for example, Patent Document 1). However, if the rigidity of the sidewalls is simply increased by simply using the reinforcing member to achieve high steering stability, the same problem will occur, and steering stability while maintaining the load durability at the same level as before. It is difficult to improve.
JP-A-9-207517

  An object of the present invention is to provide a pneumatic tire capable of improving the handling stability while maintaining the load durability at the same level as the conventional one.

  In the pneumatic tire of the present invention that achieves the above object, bead cores are embedded in the left and right bead portions, bead fillers extending to the respective sidewall portions are provided on the outer peripheral side of each bead core, and 2 between the left and right bead portions. In a pneumatic tire in which a plurality of carcass layers are extended and a plurality of belt layers are arranged on the outer peripheral side of the carcass layer in the tread portion, the tire is between two carcass layers in each sidewall portion and from the outer peripheral end of the bead filler. A rubber sheet layer made of rubber having a 50% modulus of 0.5 to 10 MPa is annularly arranged along the tire circumferential direction in a side region located on the radially outer side.

  In the other pneumatic tire of the present invention, bead cores are embedded in the left and right bead portions, bead fillers extending to the respective sidewall portions are provided on the outer peripheral side of each bead core, and two layers are provided between the left and right bead portions. In a pneumatic tire in which a direction of attaching to a vehicle is specified, a belt portion is positioned at least on the outer side of the vehicle. A rubber sheet layer made of rubber having a 50% modulus of 0.5 to 10 MPa is provided in a side region located between the two carcass layers and on the outer side in the tire radial direction from the outer peripheral end of the bead filler extending to the sidewall portion. It is characterized by being arranged in an annular shape along the tire circumferential direction.

  According to the above-described present invention, a rubber sheet layer having a 50% modulus of 0.5 MPa or more is disposed between the carcass layers of the sidewall portion, and a sandwich structure including both the carcass layers and the rubber sheet layer therebetween is provided. The rigidity of the sidewall portion can be effectively increased. As a result, the handling stability can be improved.

  Moreover, the rubber sheet layer is made of rubber having a 50% modulus of 10 MPa or less, and sandwiching it between the carcass layers can suppress delamination between the rubber sheet layer and the carcass layer. Is positioned on the outer side in the tire radial direction from the outer peripheral edge of the bead filler, so that it is possible to avoid stress concentration on the inner peripheral edge of the rubber sheet layer by avoiding overlap with the hard bead filler, so load durability Can be maintained at the same level as before.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an embodiment of the pneumatic tire of the present invention, where 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion.

  A reinforcing cord (not shown) extending between the left and right bead portions 3 through the tread portion 1 and the left and right sidewall portions 2 at an angle of 90 ° ± 10 ° with respect to the tire circumferential direction is predetermined in the tire circumferential direction. Two carcass layers 4, 5 arranged at intervals are extended, and both end portions 4 a, 5 a are outside from the inside of the tire so that bead fillers 7 are sandwiched around bead cores 6 embedded in the left and right bead portions 3, respectively. It is folded back. The bead filler 7 provided on the outer peripheral side of each bead core 6 extends to each sidewall portion 2.

  On the outer peripheral side of the carcass layers 4 and 5 of the tread portion 1, a plurality of (two layers in the figure) belt layers 8 and 9 in which reinforcing cords (not shown) are inclinedly arranged in the tire circumferential direction are arranged. A plurality of belt cover layers 10 in which reinforcing cords are spirally wound in the tire circumferential direction are provided on the outer peripheral side of the belt layers 8 and 9 of the tread portion 1.

  Both end portions 4 a of the inner carcass layer 4 extend beyond the outer peripheral end 7 a of the bead filler 7 to the outer side in the tire radial direction. Both end portions 5 a of the outer carcass layer 5 are located on the inner peripheral side with respect to the outer peripheral end 7 a of the bead filler 7.

  In the left and right sidewall portions 2, the region between the two carcass layers 4 and 5 and the position of the edge 8 a of the belt layer 8 having the widest width outside the outer peripheral end 7 a of the bead filler 7 in the tire radial direction. In the side region R, one rubber sheet layer 11 made of only rubber having a 50% modulus of 0.5 to 10 MPa is arranged annularly along the tire circumferential direction. The rubber sheet layer 11 is disposed so as to overlap the end portion 4a of the inner carcass layer 4 in a side view.

  According to the above-described present invention, by forming the sandwich structure in which the rubber sheet layer 11 having a 50% modulus of 0.5 MPa or more is interposed between the carcass layers 4 and 5 of the sidewall portion 2, Stiffness can be effectively increased. Therefore, steering stability can be improved.

  On the other hand, the rubber sheet layer 11 is made of rubber having a 50% modulus of 10 MPa or less, and is sandwiched between the carcass layers 4 and 5, thereby suppressing delamination between the rubber sheet layer 11 and the carcass layers 4 and 5. In addition, by positioning the rubber sheet layer 11 on the outer side in the tire radial direction from the outer peripheral end 7 a of the bead filler 7, stress is applied to the inner peripheral end of the rubber sheet layer 11 while avoiding overlap with the bead filler 7 having high hardness. Since concentration can be prevented, it is possible to maintain load durability at the same level as before.

  If the 50% modulus of the rubber sheet layer 11 is lower than 0.5 MPa, it becomes difficult to effectively increase the rigidity of the sidewall portion 2, and the steering stability cannot be improved. Conversely, when it exceeds 10 MPa, it becomes difficult to maintain load durability at the same level as before. The 50% modulus of the rubber sheet layer 11 is measured according to JIS K6301.

  In the present invention, the thickness t (mm) of the rubber sheet layer 11 is preferably 4 mm or less. When the thickness t of the rubber sheet layer 11 exceeds 4 mm, it is not preferable from the viewpoint of load durability. More preferably, the cross-sectional crescent shape is formed so that the central side in the width direction is gradually thickened within a range of 0.5 to 3 mm.

  When the width of the side region R (the length [mm] measured along the outer carcass layer 5) is 0.4 times or more the tire cross-section height SH, the width w ( It is preferable that the length [mm] measured along the rubber sheet layer 11 is not less than 0.3 times the tire cross-section height SH in order to effectively increase the rigidity of the sidewall portion 2.

  In the above embodiment, the pneumatic tire in which the mounting direction with respect to the vehicle is not particularly specified has been described. However, in the tire shown in FIG. 1, grooves are formed in the regions 12A and 12B of the left and right tread surfaces 12 of the tire center line CL. When the area ratio is different, the area of the area 12A is larger than the area of the area 12B, and when the area 12A is mounted on the vehicle, the vehicle inner area and the area 12B are set as the vehicle outer area. In the case of a pneumatic tire in which the direction is specified, the rigidity of the sidewall portion located on the outside of the vehicle greatly affects the steering stability.

  Accordingly, in such a pneumatic tire, at least between the two carcass layers 4 and 5 of the sidewall portion 2 located outside the vehicle, preferably, the two carcass layers of the both sidewall portions 2 as described above. Between 4 and 5, the rubber sheet layer 11 can be disposed in the same manner as described above.

  Further, the carcass layer is not limited to two layers, and may be more than that, and any pneumatic tire having at least two (multiple) carcass layers 4 and 5 may be used.

  The present invention can be preferably used particularly for a flat tire having a tire cross-section height of less than 100 mm, but is not limited thereto.

  The tires of the present invention 1 to 3 and the comparative tire 1 having the structure shown in FIG. 1 in which the tire size is 235 / 35R19 (the tire cross-section height is 91.5 mm) and the 50% modulus of the rubber sheet layer is as shown in Table 1. , 2 and a comparative tire 3 having no rubber sheet layer, respectively.

  In the present invention tires 1 to 3 and comparative tires 1 and 2, the thickness t of the rubber sheet layer is in the range of 0.5 to 3.0 mm, the width of the side region R is 0.5 times the tire cross-section height SH, rubber The width w of the seat layer is 0.4 times the tire cross-section height SH and is common. In each of the test tires, a rayon cord (1840 dtex / 2) is used as a reinforcing cord for the carcass layer, the arrangement density is 47/50 mm, and the angle of the rayon cord with respect to the tire circumferential direction is 90 °.

  When each of these test tires was subjected to a steering stability and durability load evaluation test by the method shown below, the results shown in Table 1 were obtained.

Steering stability Each test tire is mounted on a standard rim, and is mounted on a vehicle with a displacement of 2000 cc with an air pressure of 240 kPa. A feeling test is conducted by a test driver on the test course. The index value is shown. The larger this value, the better the steering stability.

Load durability Each test tire is mounted on a standard rim, attached to a drum testing machine with an air pressure of 240 kPa, the test speed is constant at 81 km / h, and the load is changed from 4.70 kN to 0.7 kN every 2 hours. The load durability was evaluated until failure occurred, and the load durability was evaluated. The evaluation result is indicated by an index value where the comparative tire 3 is 100. The larger this value, the better the load durability.

  From Table 1, it can be seen that the tire of the present invention can improve the handling stability while maintaining the load durability at the same level as the conventional one.

It is a tire meridian principal part sectional view showing one embodiment of the pneumatic tire of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4,5 Carcass layer 4a, 5a End part 6 Bead core 7 Bead filler 7a Outer peripheral edge 8,9 Belt layer 8e Edge 11 Rubber sheet layer 12 Tread surface 12A area (vehicle inside area)
12B area (vehicle outside area)
SH Tire cross section height t Rubber sheet thickness

Claims (8)

The bead cores are embedded in the left and right bead parts, bead fillers extending to the respective side wall parts are provided on the outer peripheral side of each bead core, two carcass layers are extended between the left and right bead parts, and the carcass of the tread part is provided. In a pneumatic tire in which a plurality of belt layers are arranged on the outer peripheral side of the layer,
A rubber sheet layer made of rubber having a 50% modulus of 0.5 to 10 MPa is disposed on the side region located between the two carcass layers of each sidewall portion and on the outer side in the tire radial direction from the outer peripheral edge of the bead filler. A pneumatic tire arranged in a ring along the direction. The bead cores are embedded in the left and right bead parts, bead fillers extending to the respective side wall parts are provided on the outer peripheral side of each bead core, two carcass layers are extended between the left and right bead parts, and the carcass of the tread part is provided. In a pneumatic tire in which a plurality of belt layers are arranged on the outer periphery side of the layer, and a direction when mounting on the vehicle is specified,
The 50% modulus is 0.5 at least in the side region located at the outer side in the tire radial direction from the outer peripheral edge of the bead filler extending to the sidewall portion between the two carcass layers of the sidewall portion located outside the vehicle. A pneumatic tire in which a rubber sheet layer made of rubber of 10 MPa is arranged annularly along the tire circumferential direction.   The pneumatic tire according to claim 2, wherein a groove area ratio of the tread surface is larger in the vehicle inner region than in the vehicle outer region.   4. The pneumatic tire according to claim 1, wherein the side region is a region from the outer peripheral end of the bead filler to a position of an edge of a belt layer that is the outer side in the tire radial direction and has the widest width.   The pneumatic tire according to claim 1, 2, 3, or 4, wherein the rubber sheet layer has a maximum thickness of 4 mm or less.   In the two carcass layers, both end portions of the inner carcass layer are folded back from the inner side of the tire so as to sandwich the bead filler around the bead core, and further beyond the outer peripheral end of the bead filler, the rubber sheet layer and the side surface The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire extends to the outer side in the tire radial direction so as to overlap with each other.   The pneumatic tire according to any one of claims 1 to 6, wherein the two carcass layers have reinforcing cords arranged at an angle of 90 ° ± 10 ° with respect to the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 7, wherein a tire cross-sectional height is less than 100 mm.

Images