JP2006192957A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire, improving run flat durability without an increase in weight of the tire, and further improving riding comfort. <P>SOLUTION: In this pneumatic tire, a carcass layer 6 is extended between right and left bead parts 3, both end parts 6a of the carcass layer 6 are folded back from the inside of the tire to the outside in the periphery of a bead core 4 buried in the bead part 3, and a reinforcing rubber layer 11 having a crescent-shaped section is disposed inside of the carcass layer 6 of right and left side wall parts 2, respectively. An inclined groove 12 extending at an angle α of inclination ranging from 20 to 80 degrees to the circumferential direction T of the tire is formed at a predetermined space k along the circumferential direction T of the tire in the inner peripheral surface 11a of the reinforcing rubber layer 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire capable of run-flat traveling, and more particularly to a pneumatic tire that improves both run-flat durability and riding comfort.

  Conventionally, a reinforcing rubber layer with a crescent-shaped cross section is arranged annularly along the tire circumferential direction inside the carcass layer on the left and right sidewall parts, and the flat tire can be run by supporting the punctured tire with the reinforcing rubber layer There has been proposed a pneumatic tire (see, for example, Patent Documents 1 and 2).

In the above-described pneumatic tire capable of run-flat running, by increasing the thickness of the reinforcing rubber layer, the support capability of the punctured tire can be improved and the distance during run-flat running can be extended. However, when the thickness of the reinforcing rubber layer is increased, the tire weight is increased, so that there is a problem that tire performance such as rolling resistance and riding comfort during normal running is lowered.
Japanese Patent Laid-Open No. 5-112110 JP 2000-168319 A

  An object of the present invention is to provide a pneumatic tire capable of improving run flat durability and further improving riding comfort without increasing the tire weight.

  In order to achieve the above object, the present invention provides a carcass layer extending between left and right bead portions, and both end portions of the carcass layer are folded from the tire inner side to the outer side around a bead core embedded in the bead portion. In a pneumatic tire in which a reinforcing rubber layer having a crescent cross section is arranged inside the carcass layer in an annular shape along the tire circumferential direction, an inclination angle of 20 to 80 degrees with respect to the tire circumferential direction on the inner surface of the reinforcing rubber layer The inclined grooves extending in the step are formed at predetermined intervals along the tire circumferential direction.

  According to the present invention described above, by providing the inclined grooves on the inner surface of the reinforcing rubber layer at predetermined intervals along the tire circumferential direction, the groove portion absorbs bending while keeping the weight of the reinforcing rubber layer the same. Because it can relieve stress concentration acting on the reinforcing rubber layer that supports the punctured tire while undergoing large compression deformation during run-flat driving, while the reinforcing rubber layer is easily bent during normal driving, Both run-flat durability and ride comfort can be improved without causing an increase in tire weight.

  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.

  In the left and right bead portions 3, bead cores 4 extending in an annular shape along the tire circumferential direction T are embedded. A bead filler 5 having a triangular cross section extending to the sidewall portion 2 is disposed on the outer peripheral side of the bead core 4.

  At least one carcass layer 6 in which reinforcing cords extending in the tire radial direction are arranged at predetermined intervals along the tire circumferential direction T and embedded in the rubber layer is extended between the left and right bead portions 3, The part 6 a is folded around the bead core 4 from the tire inner side to the outer side so as to sandwich the bead filler 5, and further extends to the radially outer side of the sidewall part 2.

  On the outer peripheral side of the carcass layer 6 of the tread portion 1, a plurality of belt layers 7 in which reinforcing cords that are inclined with respect to the tire circumferential direction T are embedded in the rubber layer are disposed. On the outer peripheral side of the belt layer 7, a plurality of belt cover layers 8 are provided which are rubber-coated with organic fiber cords spirally wound in the tire circumferential direction T. On the outer peripheral side of both end portions of the belt cover layer 8, an edge cover layer 9 covered with a rubber covered organic fiber cord spirally wound in the tire circumferential direction T is disposed.

  An inner liner layer 10 facing the tire cavity 20 and extending between the left and right bead portions 3 is provided inside the carcass layer 6. Reinforcing rubber layers 11 made of crescent-shaped rubber for supporting the tire during run-flat running are provided inside the carcass layers 6 of the left and right sidewall portions 2. Each reinforcing rubber layer 11 is annularly arranged along the tire circumferential direction T between the carcass layer 6 and the inner liner layer 10, and overlaps with the bead filler 5 extending to the sidewall portion 2 in a side view of the tire. To the outer side in the tire radial direction and extending to the inner diameter side of the end portion of the belt layer 7.

  On the inner surface 11a of the reinforcing rubber layer 11 located on the tire cavity 20 side, an inclined groove 12 having a V-shaped cross section extending at an inclination angle α of 20 to 80 degrees with respect to the tire circumferential direction T is provided in the tire circumferential direction. It is formed at predetermined intervals along T. Each inclined groove 12 does not extend over the entire width w which is the length of the inner surface 11 a between the radially outer end 11 x and the inner end 11 y of the reinforcing rubber layer 11, and the inner surface 11 a of the reinforcing rubber layer 11. It is arrange | positioned in the radial direction intermediate | middle area | region where thickness becomes comparatively thick.

  The inclined groove 12 may be a V-shaped inclined groove whose cross-sectional shape is as shown in FIG. 2, or may be U-shaped as shown in FIG. 1 to 3, reference numeral 13 denotes a chafer layer disposed on the bead portion 3.

  In the present invention described above, the inclined grooves 12 are provided in the inner surface 11a of the reinforcing rubber layer 11 at predetermined intervals along the tire circumferential direction T, so that the weight of the reinforcing rubber layer 11 is made the same while the grooves are bent. Since it can be absorbed, stress concentration acting on the reinforcing rubber layer 11 that supports the tire while being largely compressed and deformed during run-flat running can be reduced compared to the conventional case, while the reinforcing rubber layer 11 is easily bent during normal running. Therefore, both run-flat durability and ride comfort can be improved without increasing the tire weight.

  When the inclination angle α is smaller than 20 degrees, stress tends to concentrate on the inclined groove 12 during run-flat travel, and the run-flat durability is conversely reduced. On the other hand, when the inclination angle α exceeds 80 degrees, the section modulus increases, and the riding comfort deteriorates. Preferably, it is 30 to 60 degrees.

  The depth d (mm) of the inclined groove 12 should be 10% or more of the thickness t (mm) of the portion of the reinforcing rubber layer 11 where the inclined groove 12 is formed before the inclined groove 12 is formed. From the viewpoint of sex. The upper limit is 50% or less, preferably 40% or less from the viewpoint of run-flat durability.

  The interval k (mm) between the inclined grooves 12 may be 50% or less, preferably 30% or less, of the width w (mm) of the reinforcing rubber layer 11. When the distance k exceeds 50% of the width w of the reinforcing rubber layer 11, it becomes difficult to improve riding comfort. The lower limit of the interval k is preferably 10% or more of the width w of the reinforcing rubber layer 11 from the viewpoint of run-flat durability.

  Although this invention can be preferably used especially for the pneumatic tire used for a passenger car, it is not limited to it.

  In a test tire having a tire size of 245 / 40R18 and the configuration shown in FIG. 2, the inclination angle α (°) with respect to the tire circumferential direction of the inclined groove formed on the inner surface of the reinforcing rubber layer was changed, and the evaluation method shown below was performed. When the flat durability and riding comfort were examined, the results shown in FIG. 4 were obtained.

In FIG. 4, the solid line indicates run-flat durability, and the broken line indicates ride comfort. The reinforcing rubber layer of each test tire has the same weight, the depth of the inclined groove is about 30% of the thickness before forming the inclined groove of the reinforcing rubber layer where the inclined groove is formed, and the interval between the inclined grooves is the reinforcing rubber. About 10% of the width of the layer.
Run-flat durability Each test tire is mounted on a rim with a rim size of 18 x 8 JJ, mounted at the right side of the front wheel of a 4300cc rear-wheel drive vehicle with an air pressure of 0 kPa, and an elliptical round test course at 80 km / h. Running clockwise, the test driver felt the abnormal vibration due to tire failure and measured the distance traveled until he stopped driving.

The evaluation results are shown as index values with a conventional tire having no inclined grooves as 100. The larger this value, the better the run flat durability. Other than the front right wheel of the front wheel drive vehicle, tires and rims of the same size as above were used, and the air pressure was set to 230 kPa.
Riding comfort Each of the four test tires was attached to a rim having a rim size of 18 × 8 JJ, and the air pressure was set to 230 kPa and mounted on a rear-wheel drive vehicle having a displacement of 4300 cc. A feeling test was conducted by a test driver on a test course. The evaluation results are shown as index values with a conventional tire having no inclined grooves as 100. The larger this value, the better the ride comfort.

  It can be seen from FIG. 4 that the run-flat durability and riding comfort can be improved by setting the inclined grooves formed on the inner surface of the reinforcing rubber layer in the range of 20 to 80 degrees with respect to the tire circumferential direction.

  In the test tire having the same tire size and tire configuration as in Example 1, the depth d (mm) of the inclined groove formed on the inner surface of the reinforcing rubber layer is set to the inclined groove of the reinforcing rubber layer portion where the inclined groove is formed. When the thickness t (mm) before formation was changed and the run-flat durability and riding comfort were examined by the evaluation method shown in Example 1, the results shown in FIG. 5 were obtained.

  Also in FIG. 5, a solid line shows run flat durability and a broken line shows riding comfort. The reinforcing rubber layer of each test tire has the same weight, the inclination angle of the inclined groove is about 30 degrees, and the interval between the inclined grooves is about 10% of the width of the reinforcing rubber layer.

  From FIG. 5, it can be seen that the depth of the inclined groove is preferably in the range of 10 to 50% of the thickness of the reinforcing rubber layer portion where the inclined groove is formed before the inclined groove is formed.

  In a test tire having the same tire size and tire configuration as in Example 1, the interval k (mm) between the inclined grooves formed on the inner surface of the reinforcing rubber layer was changed with respect to the width w (mm) of the reinforcing rubber layer. When the riding comfort was examined by the evaluation method shown in Example 1, the results shown in FIG. 6 were obtained.

  In each test tire, the reinforcing rubber layer has the same weight, the inclination angle of the inclined groove is about 30 degrees, and the depth of the inclined groove is the thickness of the reinforcing rubber layer portion where the inclined groove is formed before the inclined groove is formed. About 30%.

  FIG. 6 shows that the interval between the inclined grooves should be 50% or less of the width of the reinforcing rubber layer.

It is a principal part section perspective view showing one embodiment of the pneumatic tire of the present invention. It is principal part sectional drawing which shows other embodiment of the pneumatic tire of this invention. It is principal part sectional drawing which shows other embodiment of the pneumatic tire of this invention. FIG. 6 is a graph showing the results of Example 1, wherein the horizontal axis is the inclination angle (°) of the inclined groove, and the vertical axis is an index value with the conventional tire as 100. The graph which shows the result of Example 2, the horizontal axis is the ratio d / t (%) of the depth d of the inclined groove and the thickness t of the reinforcing rubber layer, and the vertical axis is an index value where the conventional tire is 100. It is. FIG. 5 is a graph showing the results of Example 3, in which the horizontal axis is the ratio k / w (%) between the interval k between the inclined grooves and the width w of the reinforcing rubber layer, and the vertical axis is an index value with the conventional tire as 100. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Bead core 5 Bead filler 6 Carcass layer 6a End part 7 Belt layer 11 Reinforcement rubber layer 11a Inner surface 12 Inclined groove T Tire circumferential direction d Depth k Interval t Thickness w Width α Inclination angle

Claims (4)

A carcass layer is extended between the left and right bead parts, and both ends of the carcass layer are folded from the inside of the tire to the outside around the bead core embedded in the bead part, and a crescent cross section is formed inside the carcass layer of the left and right side wall parts. In the pneumatic tire in which the reinforcing rubber layer is annularly arranged along the tire circumferential direction,
A pneumatic tire in which inclined grooves extending at an inclination angle of 20 to 80 degrees with respect to the tire circumferential direction are formed on the inner surface of the reinforcing rubber layer at predetermined intervals along the tire circumferential direction.   The pneumatic tire according to claim 1, wherein a cross-sectional shape of the inclined groove is V-shaped or U-shaped.   The pneumatic tire according to claim 1 or 2, wherein a depth of the inclined groove is 10 to 50% of a thickness of the reinforcing rubber layer portion where the inclined groove is formed before the inclined groove is formed.   The pneumatic tire according to claim 1, 2, or 3, wherein the interval between the inclined grooves is 50% or less of the width of the reinforcing rubber layer.

Images