JP2014118083A - Run-flat tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a run-flat tire that can strike a balance between the high quality performance in the normal running and the durability performance in the run-flat running.SOLUTION: A run-flat tire 10 of the present invention is configured as follows: a tire radius direction distance D1 from a virtual tread edge P to the most outside position C in the radial direction of a tire and a cross section height SH of the tire satisfy a relationship of D1≥0.15 SH in the cross section of the tire width direction; and a tire radius direction distance D2 from a dot on a tread surface at the position apart by 0.6 TW outside in a tire width direction from a tire equatorial plane CL with respect to a tire width direction distance TW from the tire equatorial plane CL of the virtual tread edge P to the most outside position C in the tire radial direction and the cross section height SH satisfy the relationship of D2≤0.05 SH.

Description

  The present invention relates to a run-flat tire in which a side reinforcing rubber having a crescent-shaped cross section along the tire width direction is disposed on a tire side portion.

  In the so-called side-reinforced run-flat tire in which a side reinforcing rubber having a crescent cross-sectional shape along the tire width direction is provided on the tire side portion, the side reinforcing rubber is caused by the arrangement of the side reinforcing rubber on the tire side portion. It is known that the longitudinal spring constant of the tire increases and the ride comfort performance decreases.

  Patent Document 1 discloses an invention in which the tread has a very round outline shape, so that the rubber volume of the side reinforcing rubber layer can be reduced, and the increase in tire mass and the decrease in ride comfort are kept low while ensuring the run-flat performance. Is described.

JP 2007-069775 A

  However, in the tire described in Patent Document 1, the tread has a very round outline shape, and the volume of the side reinforcing rubber that can be provided on the tire side portion is reduced, thereby reducing the side reinforcing rubber layer during run flat running. There is a concern that the run-flat durability performance deteriorates due to the increase of the strain.

  The run-flat tire of the present invention is arranged on a tire side portion including a carcass composed of one or more carcass plies extending from each of a pair of bead portions through each sidewall portion to a tread portion, and the bead portion and the sidewall portion. A run-flat tire comprising: a side reinforcing rubber having a crescent-shaped cross section along the tire width direction; and a tread rubber disposed on the outer side in the tire radial direction of the crown region of the carcass to form a tread surface. In the cross section in the tire width direction, a tire outer contour shape has a curved portion having a minimum radius of curvature among a plurality of outer contour curves forming the tread surface in a tire width direction outer end region of the tread surface. Including two adjacent outer contour lines that are adjacent to the inner side and the outer side in the tire width direction with the curved portion interposed therebetween, The intersection of the tangents of the curved portion at each contact point with the line portion is defined as a virtual tread end, a tire radial distance D1 from the virtual tread end to the outermost position in the tire radial direction, and the tire The cross-sectional height SH satisfies the relationship of D1 ≧ 0.15SH, and with respect to the tire width direction distance TW from the tire equatorial plane at the virtual tread end, only 0.6 TW from the tire equatorial plane to the outer side in the tire width direction. The distance D2 in the tire radial direction from the point on the tread surface at the distant position to the outermost position in the radial direction of the tire and the cross-sectional height SH satisfy the relationship of D2 ≦ 0.05SH. .

  The “tire cross-sectional height SH” in the present invention is a cross section in the tire width direction, and is a distance along the tire radial direction from the bead base to the outermost position in the radial direction of the tire.

  In the present invention, the “tire half width SW of the tire” means 1/2 of the total width of the tire, excluding the pattern and characters on the side of the tire, and the “total width” means the side of the tire. The maximum distance in the tire width direction between sidewall parts including all patterns and characters.

  In the present invention, “the tire radial direction distance D1 from the virtual tread edge to the outermost position in the radial direction of the tire”, “the surface of the tread at a position away from the tire equator plane by 0.6 TW outward in the tire width direction” "Tire radial distance D2 from the upper point to the outermost position in the radial direction of the tire", "Tire cross-sectional height SH", "The tire width direction distance TW of the virtual tread edge from the tire equatorial plane", The “tire half width SW of the tire” and the “radius of curvature” are measured in a no-load state in which the tire is assembled to the applicable rim and filled with the specified internal pressure.

  Here, “applicable rim” refers to a rim defined in the following standards according to the tire size, and “specified internal pressure” refers to an air pressure defined in accordance with the maximum load capacity in the following standards. “Maximum load capacity” means the maximum mass allowed to be loaded on a tire according to the following standards. The standard is determined by an industrial standard effective in the region where the tire is produced or used. For example, in the United States, “THE TIRE AND RIM ASSOCIATION INC.” Is “YEAR BOOK” In Europe, it is “STANDARDS MANUAL” of “The European Tire and Rim Technical Organization”, and in Japan, it is “JATMA YEAR BOOK” of “Japan Automobile Tire Association”.

  Provided is a run-flat tire that can achieve a high level of compatibility between ride performance during normal running and durability during run-flat running.

1 is a cross-sectional view along the tire width direction showing one embodiment of a run-flat tire of the present invention with respect to a tire half portion.

Embodiments of the present invention will be described below with reference to the drawings.
A run flat tire 10 illustrated in FIG. 1 includes a tread portion 1, a pair of sidewall portions 2 (only one side is illustrated) extending inward in the tire radial direction from each side portion of the tread portion 1, and each sidewall portion 2. These are composed of a pair of bead portions 3 (only one side is shown) that are connected to the inner side in the tire radial direction. Here, the side wall portion 2 and the bead portion 3 are included and referred to as a tire side portion 20.

  The illustrated run flat tire 10 extends in a toroidal shape from each of the bead cores 6 embedded in the pair of bead portions 3 and from each of the pair of bead portions 3 to the tread portion 1 through each sidewall portion 2. A carcass 4 composed of one or more carcass plies in the figure, and a tire radius of the bead core 6. A bead filler 7 disposed between the main body portion 4a and the folded portion 4b of the carcass 4 on the outer side in the direction, a belt 5 disposed on the outer side in the tire radial direction of the crown region of the carcass 4, and the tire radial direction of the belt 5 And a tread rubber 11 disposed outside and forming a tread surface.

  Here, for example, the carcass 4 that can have a radial structure by a carcass ply formed by extending an organic fiber cord or a steel cord in the radial direction is continuous with the main body portion 4a and around the bead core 6. The body portion 4a is moored to the bead portion 3 by the folded portion 4b that is folded back.

  Here, the belt 5 positioned on the outer side in the tire radial direction of the carcass 4 is formed by extending a cord made of steel or organic fiber in a direction inclined with respect to the tire circumferential direction, as shown in FIG. The inner belt layer 51 and the outer belt layer 52 formed by extending the cord in a direction crossing the cord of the inner belt layer 51 are sequentially arranged toward the outer side in the tire radial direction, and the inner and outer sides thereof are arranged. A belt reinforcing layer 53 made of a cord extending substantially in the tire circumferential direction can be disposed outside the belt layers 51 and 52 in the tire radial direction. However, the configuration, the arrangement area, the number of layers, and the like of the belt layer and the like can be changed as appropriate.

  Furthermore, the main body portion of the carcass 4 includes the inner liner 8 that is disposed on the inner side in the tire width direction of the main body portion 4a of the carcass 4 and that forms the inner surface of the tire and is made of a rubber material having excellent air impermeability, and the tire side portion 20. A pair of side reinforcing rubbers 9 (only one side is shown) interposed between 4a and the inner liner 8 are provided.

Here, the side reinforcing rubber 9 has a thickness that gradually decreases from the central region in the tire radial direction toward the inner side and the outer side in the tire radial direction within the cross section in the tire width direction shown in FIG. 1. In addition, each of the inner surface facing the inner side in the tire width direction and the outer surface facing the outer side in the tire width direction has a substantially crescent shape formed by curving convexly toward the outer side in the tire width direction. The side reinforcing rubber 9 has a maximum thickness Ga in the central region in the tire radial direction. Here, the maximum thickness Ga of the side reinforcing rubber 9 is a cross section along the width direction of the tire, a point on the inner surface of the side reinforcing rubber 9 in the tire width direction that forms a curve, and a normal line drawn at that point. Is the maximum value of the distance between the side reinforcing rubber 9 and the point of intersection with the outer surface in the tire width direction.
By arranging the side reinforcing rubber 9 as described above, the side reinforcing rubber 9 that contributes to supporting the weight of the vehicle body can safely travel a certain distance even when the internal pressure of the tire is reduced due to puncture or the like. To.

By the way, in the outer contour shape in the cross section in the width direction of the tire, as shown in FIG. 1, the tread surface is formed by connecting, for example, a plurality of outer contour lines that are linear or have different curvature radii. However, among these outer contour lines, a curve portion R1 having a minimum radius of curvature among a plurality of outer contour curves that exist in the tire width direction outer end region of the tread surface and form the tread surface. And And tangent line T1 of curve part R1 in each contact Q1, Q2 of two adjacent outside outline X1, X2 and curve part R1 which adjoin each inside and outside of a tire width direction across this curve part R1, In the present invention, the intersection where T2 intersects each other is defined as a virtual tread end P. In the present invention, in the illustrated cross section along the tire width direction, from the virtual tread end P to the outermost position C in the radial direction of the tire. The tire radial direction distance D1 and the tire cross-section height SH are:
D1 ≧ 0.15SH
Satisfy the relationship.

Here, as shown in FIG. 1, the sectional height SH of the tire refers to a distance along the tire radial direction from the bead base to the outermost position C in the radial direction of the tire in a section in the tire width direction. The curved portion R1 extends over the width direction region including the tire ground contact edge that is the outermost position in the width direction of the tread surface.
Each of the two adjacent outer contour lines X1 and X2 adjacent to the inner and outer sides in the tire width direction with the curved portion R1 interposed therebetween is a curve formed by one arc having a constant radius of curvature or one straight line. be able to. When the adjacent outer contour lines X1 and X2 are curved, the radius of curvature is larger than the radius of curvature of the curved portion R1.

  According to this, when the contact pressure is applied by increasing the distance in the tire radial direction from the outer surface of the tire to the outermost position C in the radial direction of the tire in the tire width direction end region of the tread portion 1. In addition, the tread portion 1 is easily deformed inward in the tire radial direction, and the variation of the load on the tire due to the action of different ground pressure is handled by the deformation of the tread portion 1 rather than the deformation of the tire side portion 20. Therefore, the vertical spring constant of the tire is reduced. As a result, it is possible to improve riding comfort performance during normal driving.

  Further, in the present invention, the outermost position C in the radial direction of the tire from a point on the tread surface at a position separated by 0.6 TW from the tire equatorial plane CL to the outer side in the tire width direction in the same width direction cross section shown in the figure. It is assumed that the tire radial distance D2 and the tire cross-section height SH satisfy the relationship D2 ≦ 0.05SH. Here, TW is the distance in the tire width direction of the virtual tread edge P from the tire equatorial plane CL.

The tire radial direction distance D2 at a position 0.6 TW away from the tire equatorial plane CL and the tire cross-section height SH satisfy the above relationship, so that 0 from the tire equatorial plane CL to the outside in the tire width direction. It is possible to shorten the distance in the tire radial direction from the tread surface to the outermost position C in the radial direction of the tire in the intermediate region in the width direction of the tread portion 1 located on the inner side in the tire width direction from the position separated by 6 TW. . As a result, a large ground contact area can be ensured, so that distortion to the side reinforcing rubber 9 during run-flat running can be kept small, and run-flat durability performance can be improved.
That is, when the distance D2 and the cross-sectional height SH satisfy the relationship of D2> 0.05SH, from the end region on the outer side in the tire width direction of the tread portion to the entire intermediate region, Since the distance in the tire radial direction from the tread surface to the outermost position in the radial direction of the tire is increased and the contact area is reduced, the strain on the side reinforcing rubber increases during run-flat driving. It cannot be improved sufficiently.

  Here, in the illustrated cross section along the tire width direction, the tire radial direction distance D1 from the virtual tread end P to the outermost position C in the radial direction of the tire and the cross sectional height SH of the tire are further D1 ≧ 0. It is preferable to satisfy the relationship of .2SH. According to this, the tire radial direction distance from the tire outer surface to the outermost position C in the radial direction of the tire in the tire width direction end region of the tread portion 1 can be further increased. Thereby, the longitudinal spring constant of the tire is further reduced, and further improvement in riding comfort performance during normal traveling can be realized.

  Here, in the present invention, the distance D2 in the tire radial direction from the point on the tread surface to the outermost position C in the radial direction of the tire at a position 0.6 TW away from the tire equatorial plane CL in the tire width direction outside. And the tire cross-section height SH preferably satisfy the relationship of D2 ≦ 0.04SH. According to this, the distance in the tire radial direction from the tread surface in the intermediate region in the width direction of the tread portion 1 to the outermost position C in the radial direction of the tire can be further shortened. Thereby, the further improvement of run-flat durability performance is realizable.

Also preferably, the tire width direction distance TW from the tire equatorial plane CL of the virtual tread edge P and the tire half-width SW satisfy the relationship of TW ≧ 0.94SW, and further TW ≧ 0.96SW It is preferable to satisfy the relationship.
In this case, by increasing the tire width direction distance TW of the virtual tread end P from the tire equatorial plane CL with respect to the tire half-width, the side reinforcing rubber at the time of run-flat running based on the increase in the contact area 9 can be prevented from generating a large strain and the run-flat durability performance can be improved.
In other words, when the distance TW and the tire half-width SW satisfy the relationship of TW <0.94SW, the distance TW becomes shorter, so the end of the tread portion on the outer side in the tire width direction In the tire of the present invention in which the tire radial direction distance from the tread surface in the region to the outermost position in the radial direction of the tire is increased as described above, the distortion generated in the side reinforcing rubber during run flat running increases. There is a possibility that the run-flat durability performance cannot be sufficiently improved.

  In addition, it is preferable that the curvature radius of curve part R1 shall be 35 mm or less. As a result, the distance in the tire radial direction from the surface of the curved portion R1 to the outermost position C in the radial direction of the tire is shorter than in the case where the radius of curvature of the curved portion R1 is larger than 35 mm. Can be secured, and the tire side portion 20 can be prevented from being collapsed outwardly in the tire width direction. Thereby, the distortion which generate | occur | produces in the side reinforcement rubber 9 at the time of run flat driving | running | working can be suppressed, and run flat durability performance can be improved. From such a viewpoint, it is more preferable that the radius of curvature of the curved portion R1 is 25 mm or less.

  Here, the tire radial direction distance D1 from the virtual tread end P to the outermost position C in the radial direction of the tire and the tire width direction distance TW of the virtual tread end P from the tire equatorial plane CL are D1 ≧ 0. It is preferable to satisfy the relationship of .15 TW, particularly the relationship of D1 ≧ 0.2 TW. According to this, the ratio of the distance in the tire radial direction from the outer surface of the tire to the outermost position C in the radial direction of the tire in the outer end region in the tire width direction of the tread portion 1 can be increased. . Thereby, since the tread portion 1 is more easily deformed by the action of the contact pressure, the vertical spring constant of the tire is reduced, and the riding comfort performance during normal running can be improved.

  In this embodiment, the above-mentioned “distance”, “width”, and other lengths are assembled to a standard rim specified by JATMA and under the condition of a tire filled with an internal pressure of 180 kPa, which is a specified internal pressure. Measured.

  The performance was evaluated by the following methods for Example tires 1 to 5 and Comparative tires 1 to 4 having the configuration shown in FIG. The evaluation results are shown in Table 1.

<Vertical spring constant>
70% of the load corresponding to the maximum load capacity in a state in which each of the above-described Example tires 1 to 5 and Comparative Example tires 1 to 4 is assembled to a standard rim defined by JATMA and filled with a tire internal pressure of 230 kPa. Was applied in the tire radial direction, and the deflection of the tire in the tire radial direction was measured. The measurement results are expressed as index values based on the comparative example tire 1 for the example tires 1 and 2 and the comparative example tire 1, and for the example tires 3 and 4 and the comparative example tires 2 and 3. The index value based on the comparative example tire 2 is used, and the example tire 5 and the comparative example tire 4 are expressed using the index value based on the comparative example tire 4.
Here, the index values shown in Table 1 indicate that the smaller the numerical value, the better the riding comfort performance.

<Run flat durability performance evaluation test>
Example tires 1 to 5 and comparative tires 1 to 4 were each assembled on a JATMA standard rim, with an internal pressure of 0 kPa, a valve core removed, a load of 65% of the maximum load, and a run flat durability at a speed of 80 km / h. A drum test was performed and the travel distance was measured. The measurement results are represented by index values based on the comparative example tire 1 for the example tires 1 and 2 and the comparative example tire 1, and the comparative examples for the example tires 3 and 4 and the comparative example tires 2 and 3. The index value is based on the tire 2, and the example tire 5 and the comparative example tire 4 are expressed as index values based on the comparative example tire 4.
Here, the index values shown in Table 1 indicate that the larger the numerical value, the better the run-flat durability performance.

From the results shown in Table 1, the example tires 1 to 5 exhibit the same run flat durability performance as the comparative example tires 1, 2, and 4, and the vertical spring constant is smaller than that of the comparative example tires 1 to 4. I understand that.
Therefore, according to the run-flat tire of the present invention, it is possible to improve the riding comfort during normal running while ensuring the required run-flat durability performance. It is possible to achieve a high level of durability performance.

1 tread part, 2 side wall part, 3 bead part, 4 carcass, 4a carcass body part, 4b carcass folded part, 5 belt, 6 bead core, 7 bead filler, 8 inner liner, 9 side reinforcing rubber, 10 run flat tire, 11 tread rubber, 20 tire side portion, 51 inner belt layer, 52 outer belt layer, 53 belt reinforcing layer, C outermost position in radial direction of tire, CL tire equatorial plane, P virtual tread edge, Q1, Q2 contact point, R1 Curved part, X1, X2 Adjacent outer contour line

Claims (5)

A carcass composed of one or more carcass plies extending from each of the pair of bead portions to the tread portion through each sidewall portion, and the tire side portion including the bead portion and the sidewall portion, along the tire width direction. A run-flat tire comprising a side reinforcing rubber having a crescent cross-sectional shape and a tread rubber disposed on the outer side in the tire radial direction of the crown region of the carcass to form a tread surface,
In the cross section in the tire width direction, the tire outer contour shape includes a curved portion having a minimum radius of curvature among the plurality of outer contour curves forming the tread surface in the tire width direction outer end region of the tread surface,
Each of the tangents of the curved portion at each contact point between the curved and linear adjacent outer contour lines adjacent to the inner and outer sides in the tire width direction across the curved portion and the curved portion is mutually The intersecting intersection is defined as a virtual tread edge, and the tire radial direction distance D1 from the virtual tread edge to the outermost position in the tire radial direction and the tire cross-section height SH satisfy the relationship of D1 ≧ 0.15SH,
The radial direction of the tire from a point on the tread surface at a position separated by 0.6 TW from the tire equatorial plane to the outer side in the tire width direction with respect to the tire width direction distance TW from the tire equatorial plane at the virtual tread end. A run-flat tire characterized in that a tire radial distance D2 to the outermost position and the cross-sectional height SH satisfy a relationship of D2 ≦ 0.05SH. 2. The run-flat tire according to claim 1, wherein a distance TW in the tire width direction from the tire equatorial plane at the end of the virtual tread and a cross-sectional half width SW of the tire satisfy a relationship of TW ≧ 0.94SW. .   The run flat tire according to claim 1 or 2, wherein a radius of curvature of the curved portion is 35 mm or less.   The relationship of the tire radial direction distance D1 from the virtual tread end to the outermost position in the radial direction of the tire and the tire width direction distance TW of the virtual tread end from the tire equatorial plane is D1 ≧ 0.15TW. The run flat tire according to any one of claims 1 to 3, wherein: The tire radial direction distance D2 from the point on the tread surface to the outermost position in the radial direction of the tire and the cross-sectional height SH at a position separated from the tire equatorial plane by 0.6 TW outward in the tire width direction, The run-flat tire according to any one of claims 1 to 4, wherein a relationship of D2≤0.04SH is satisfied.

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