JP5371528B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire according to a run-flat tire with improved run-flat durability.

  2. Description of the Related Art Conventionally, run flat tires that can safely travel a certain distance (run flat travel) even if the tire punctures are widely known. In order to improve the durability of the run flat tire during puncture, it is effective to set the thickness of the reinforcing rubber layer to be thick. However, in this case, there is a problem that the tire rigidity becomes too high and the riding comfort of the vehicle is lowered. In view of this, a tire has been developed that embeds soft rubber having a wedge-shaped or triangular cross-section having a low hardness in the reinforcing rubber layer (see, for example, Patent Document 1).

JP 2007-50719 A

  However, in the run flat tire described in Patent Document 1, since the tip of the soft rubber is formed at an acute angle, stress is concentrated on the tip during rolling of the tire, and the starting point at which damage or the like occurs in the reinforcing rubber layer As a result, run-flat durability (a possible distance for run-flat travel) may be reduced.

  An object of the present invention is to provide a pneumatic tire that is less likely to cause stress concentration during tire rolling and has high run-flat durability.

A first aspect of the present invention, Oite the sidewall portion, the inner side of the carcass layer in the tire width direction, a pneumatic tire reinforcing rubber layer is provided to reinforce the sidewall portion, the tire width the inner surfaces constituting the inside of the reinforcing rubber layer in the direction, the plurality of recesses recessed outward in the tire width direction are formed, each of the plurality of recesses, continuously along the tire circumferential direction extending and and are provided at predetermined intervals in the tire radial direction, each of said plurality of recesses, the plurality of insertion rubber lower hardness than the reinforcing rubber layer is embedded, wherein the plurality of inserts each of the rubber, the have substantially the same length in the tire width direction, and are formed integrally, along the tire width direction and the tire radial direction cross-section Oite, the bottom surface of each of the respective tips and the plurality of recesses of the plurality of insertion rubber, and summarized in that formed in an arc shape which is curved towards the outside in the tire width direction.

  As described above, since the bottom surface of the recess and the tip of the insertion rubber that fits into the recess are formed in an arc shape, no stress is concentrated on the arc-shaped portion when the tire rolls, and the tire run flat Durability can be improved efficiently. Moreover, rigidity is hold | maintained by a site | part with high hardness other than the insertion rubber 22 among the reinforcement rubber layers 20, and the vibration by the road surface input at the time of normal driving | running | working by the insertion rubber 22 can fully be absorbed. In addition, since the insertion rubber 22 is integrally formed continuously along the tire circumferential direction, it can be formed simultaneously with the reinforcing rubber layer 20 by extrusion molding, and high productivity can be maintained.

  According to the present invention, it is possible to obtain a pneumatic tire that is less likely to cause stress concentration during tire rolling and that has high run-flat durability.

1 is a cross-sectional view in the width direction of a pneumatic tire according to a first embodiment of the present invention. It is sectional drawing which expanded and showed the principal part of FIG. 1 typically. It is sectional drawing of the width direction of the pneumatic tire by 2nd Embodiment of this invention. It is sectional drawing of the width direction of the pneumatic tire of the comparative example in an Example.

  Hereinafter, details of a pneumatic tire according to an embodiment of the present invention will be described with reference to the drawings. However, it should be noted that the drawings are schematic, and the thicknesses and ratios of the material layers are different from actual ones. Accordingly, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, the part from which the relationship and ratio of a mutual dimension differ also in between drawings is contained.

  First, the pneumatic tire 1 according to the first embodiment of the present invention will be described. The pneumatic tire may be filled with an inert gas such as nitrogen gas.

<Schematic configuration of pneumatic tire>
FIG. 1 is a cross-sectional view in the width direction of a pneumatic tire according to a first embodiment of the present invention.

  The pneumatic tire 1 includes a pair of annular bead cores 2 and 2 that are spaced apart in the tire width direction, a carcass 3 that serves as a skeleton of a tire that connects these bead cores 2 and 2 in a toroidal shape, A two-layer belt layer 4 disposed on the crown portion 3a disposed in the center portion in the width direction of the carcass 3; and a belt protection layer 5 that covers the width direction end portion of the belt layer 4 from the outside of the diameter. ing.

  Further, a crown portion 3a of the carcass 3, a belt layer 4, a belt protective layer 5 and a tread portion 6 made of a tread rubber covering these are formed at the center in the width direction of the pneumatic tire 1. A circumferential groove 7 extending along the tire circumferential direction is formed in the tread portion 6, and shoulder portions 8, 8, sidewall portions 9, 9 and bead portions 10, 10 are formed on the left and right sides of the tread portion 6. It is provided in a pair.

  A reinforcing rubber layer 20 having a substantially crescent-shaped cross section is provided on the inner side in the tire width direction of the sidewall portion 9. The reinforcing rubber layer 20 has a narrow width dimension at the outer radial end 20a on the outer side in the tire radial direction. The width of the reinforcing rubber layer 20 gradually increases from the outer radial end 20a toward the inner side in the tire radial direction. The width dimension is the largest at the substantially central portion of the cross-sectional height, and the width dimension is gradually narrowed toward the inner diameter end 20b. Further, the inner side surface in the width direction of the reinforcing rubber layer 20 is formed with a concave portion 21 that is convex toward the outer side in the width direction and that extends continuously along the tire circumferential direction. A plurality of the recesses 21 are formed at predetermined intervals along the tire radial direction, and an insertion rubber 22 is embedded in these recesses 21. Accordingly, both the recess 21 and the insertion rubber 22 are arranged along the tire radial direction, and the lengths in the width direction are set to be substantially the same. In addition, it is preferable to form a plurality of the recesses 21 and the insertion rubbers 22 at intervals of 10 mm in the tire radial direction centering on the maximum width position of the tire.

  FIG. 2 is a cross-sectional view schematically showing an enlarged main part of FIG.

  As described above, the recess 21 and the insertion rubber 22 fitted to the recess 21 extend toward the outer side in the tire width direction. In particular, the insertion rubber 22 includes the main body portion 22a disposed on the inner side in the width direction and the main body. It is integrally formed with the front-end | tip part 22b arrange | positioned at the width direction outer side of the part 22a. The main body portion 22a has a substantially constant thickness in the tire radial direction, and the distal end portion 22b is formed in a substantially arc shape with a radius of curvature R. Therefore, the thickness of the insertion rubber 22 is T, and the length in the tire width direction is set to W. The hardness of the insertion rubber 22 is set lower (softer) than that of the reinforcing rubber layer 20. Specifically, the hardness of the insertion rubber 22 is preferably set to a JIS-A hardness of 40 to 55, and the hardness of the reinforcing rubber layer 20 is preferably set to a JIS-A hardness of 75 to 90. .

  Below, the effect by embodiment of this invention is demonstrated.

<Operation effect>
(1) A reinforcing rubber layer 20 that reinforces the sidewall portion 9 is provided on the inner side in the tire width direction of the sidewall portion 9, and at least the reinforcing rubber layer 20 protrudes from the inner side surface in the width direction toward the outer side in the width direction. One recess 21 is formed, and an insertion rubber 22 having a hardness lower than that of the reinforcing rubber layer 20 is embedded in the recess 21, and the tip 22b of the insert rubber 22 and the bottom surface of the recess 21 corresponding to the tip 22b are formed. It is formed in an arc shape.

  Thus, since the bottom surface of the recess 21 and the tip 22b of the insertion rubber 22 that fits into the recess 21 are formed in an arc shape, stress is concentrated when the tire rolls on the arc-shaped portion. Thus, the run flat durability of the run flat tire can be improved efficiently.

(2) A plurality of the recesses 21 and the insertion rubbers 22 are arranged at predetermined intervals along the tire radial direction, and the length W in the tire width direction of the plurality of insertion rubbers 22 is set to be substantially constant. . Therefore, since the rigidity of the inner portion in the width direction in the reinforcing rubber layer 20 is set to be substantially constant, bending displacement in the vicinity of the tip 22b of the insertion rubber 22 at the time of tire rolling is suppressed. As a result, stress concentration in the vicinity of the tip 22b of the insertion rubber 22 is reduced, and the run-flat durability of the reinforcing rubber layer 20 is improved.

  Next, a pneumatic tire 101 according to a second embodiment of the present invention will be described. However, the same structure as that of the first embodiment is denoted by the same reference numeral, and the description thereof is omitted.

  In the present embodiment, the reinforcing rubber layer 120 having a substantially crescent-shaped cross section gradually increases in width dimension from the radially outer end 120a toward the inside of the diameter, and the tire width dimension w becomes the thickest at the position where the maximum position is reached. It becomes narrower gradually toward the inner end 20b. Further, the reinforcing rubber layer 120 is formed with a plurality of concave portions protruding in a convex shape toward the outer side in the tire width direction at predetermined intervals in the tire radial direction. These recesses are 121, 122, 123, 124, 125, 126 in order from the outer diameter side, and the recess 123 has the longest width dimension, and the width dimension gradually decreases from the recess 123 toward the outer side and the inner side of the tire diameter. It has become. The radial direction position of the recess 123 is a position where the width dimension of the reinforcing rubber layer 120 is the largest. The tips of these recesses 121 to 126 are formed in a substantially arc shape as in the first embodiment, and the insertion rubbers 131 to 136 are embedded in these recesses 121 to 126 and embedded. The radial length a along the tire radial direction from the concave portion 121 to the concave portion 126 is 0.3A ≦ a ≦ 0.7A with respect to the length A along the tire radial direction of the reinforcing rubber layer 120. It is preferable to set.

  Below, the effect by embodiment of this invention is demonstrated.

<Operation effect>
(1) The reinforcing rubber layer 120 is formed in a substantially crescent shape in cross section extending along the tire radial direction, and a plurality of recesses 121 to 126 and insertion rubbers 131 to 136 are arranged at predetermined intervals along the tire radial direction. The length of the plurality of inserted rubbers 131 to 136 in the tire width direction is the longest at the maximum width position of the reinforcing rubber layer 120, and gradually decreases as the distance from the maximum width position increases in the tire radial direction. It is set.

  Thus, the lengths of the insertion rubbers 131 to 136 in the tire width direction are set corresponding to the width direction length of the reinforcing rubber layer 120. That is, the insertion rubber 123 having the largest width dimension and the softest width is disposed at the most rigid portion of the reinforcing rubber layer 120. Here, since the insertion rubber is soft, the rigidity is lowered when the width dimension is set large, while the rigidity of the reinforcement rubber layer 120 is improved when the width dimension of the reinforcement rubber layer 120 is set large. Therefore, the insertion rubber having a large width is disposed at a portion where the rigidity of the reinforcing rubber layer 120 is increased, and the insertion rubber having a small width is disposed at a portion where the rigidity of the reinforcing rubber layer 120 is decreased. The rigidity of the entire layer 120 can be configured uniformly.

  It should not be understood that the description and the drawings, which form part of the disclosure of the above-described embodiments, limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the above-described embodiment, six concave portions and six insertion rubbers are arranged on each of the left and right sides, but the number may be set to be greater than this.

  Next, the present invention will be described more specifically through examples.

  A run flat tire according to a comparative example and an example of the present invention having a size of 205 / 45R17 was used as a test tire. Using this test tire, a ride comfort test, a vibration noise test, and a run-flat durability test were performed. In addition, as shown in FIG. 4, the pneumatic tire 201 according to the comparative example does not include a recess and an insertion rubber in the reinforcing rubber layer 220. In the pneumatic tire 1 according to the example of the present invention, as in the pneumatic tire 1 shown in FIG. 1, six insertion rubbers having the same width dimension W are arranged.

  First, for the ride comfort test, the PP (Peak to Peak value) of the axial force in the vertical direction of the tire when overcoming a rectangular cleat installed on a smooth drum is compared between the comparative example and the present invention example. Was done by. As a result, when the riding comfort in the case of the comparative example is an index 100 which is a reference value, the example of the present invention is 105. Therefore, the results of the examples of the present invention were better.

  Next, the vibration noise test was performed by measuring the in-vehicle sound while driving on the road noise test road and measuring the driver's ear measurement sound. As a result, when the low vibration noise property in the case of the comparative example was set to ± 0 as a reference value, the example of the present invention was -1. Therefore, the results of the examples of the present invention were better.

  In the run-flat durability test, the tire is damaged by running the vehicle under the conditions specified by the ISO standard (room temperature is 30 °, load is 65% of normal load, and speed is 80 km / h). The distance traveled was measured. As a result, when the run flat durability in the case of the comparative example is an index 100 as a reference value, the example of the present invention is 99. Therefore, the example of the present invention has the same durability as the comparative example.

  As described above, it was confirmed that the example of the present invention had the same run-flat durability, low vibration noise, and good riding comfort as compared to the conventional comparative example.

DESCRIPTION OF SYMBOLS 1,101 Pneumatic tire 9 Side wall part 20,120 Reinforcement rubber layer 21,121-126 Recessed part 22,131-136 Insertion rubber

Claims (1)

Oite the sidewall portion, the inner side of the carcass layer in the tire width direction, a pneumatic tire reinforcing rubber layer is provided to reinforce the sidewall portion,
Wherein the inner surfaces constituting the inside of the reinforcing rubber layer in the tire width direction, the plurality of recesses recessed outward in the tire width direction are formed,
Each of the plurality of recesses extends continuously along the tire circumferential direction, and is provided at a predetermined interval in the tire radial direction,
Wherein the each of the plurality of recesses, said reinforcement plurality of insert rubber lower hardness than the rubber layer is embedded,
Each of the plurality of insertion rubbers has substantially the same length in the tire width direction, and is formed integrally.
In a cross section along the tire width direction and the tire radial direction, the bottom surface of each of the respective tips and the plurality of recesses of the plurality of insertion rubber, formed in a circular arc shape which is curved towards the outside in the tire width direction Pneumatic tire characterized by being made .

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