JP2020185869A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire that can be improved in resistance to external wound while being reduced in weight.SOLUTION: The pneumatic tire comprises a tread part 1 extending in a tire circumferential direction to form an annular shape, a pair of side wall parts 2 arranged at both sides of the tread part 1, and a pair of bead parts 3 arranged inside in a tire radial direction of the side wall parts 2. At a position on a rim line of the side wall part 2 is provided a convex rib 10 extending across the whole circumference in the tire circumferential direction. In a state where the tire is mounted on a normal rim R and is filled with normal inner pressure, the convex rib 10 protrudes with respect to a tire width direction in a range of ±5° and a distance in the tire width direction between a tip part 11 of the convex rib 10 and a tip part of a rim flange Rf is in a range of 0 mm-10 mm.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of improving trauma resistance while reducing the weight.

Generally, in a pneumatic tire, a line for confirming that the tire is properly assembled to the rim when the tire is mounted on the rim, so-called, at a predetermined position on the sidewall portion. A rim line is provided. This rim line is usually formed as a small protrusion extending in an annular shape along the tire circumferential direction.

Further, for the purpose of improving the trauma resistance, it has been proposed to dispose a convex rim protect bar extending over the entire circumference in the tire circumferential direction on the sidewall portion (see, for example, Patent Document 1). By providing such a rim protect bar, it is possible to protect the rim flange of the rim to be mounted. However, since the rim protect bar has a larger rubber volume than the rim line, it is disadvantageous for reducing the weight of the tire.

Japanese Unexamined Patent Publication No. 11-078441

An object of the present invention is to provide a pneumatic tire capable of improving trauma resistance while reducing the weight.

In order to achieve the above object, the pneumatic tire of the present invention includes a tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and these sidewall portions. In a pneumatic tire provided with a pair of bead portions arranged inside in the tire radial direction, a convex rib extending over the entire circumference in the tire circumferential direction is provided at the position of the rim line of the sidewall portion to normalize the tire. When assembled to the rim and filled with normal internal pressure, the convex ribs protrude within a range of ± 5 ° with respect to the tire width direction, and the tire width between the tip of the convex rib and the tip of the rim flange. The distance in the direction is 0 mm to 10 mm.

In the present invention, since the convex rib extending over the entire circumference in the tire circumferential direction is provided at the position of the rim line of the sidewall portion, the convex rib can fulfill its function in place of the general rim line. .. In addition, when the tire is assembled to the regular rim and the regular internal pressure is applied, the convex rib protrudes within a range of ± 5 ° with respect to the tire width direction, and the tip of the convex rib and the tip of the rim flange Since the distance in the tire width direction is 0 mm to 10 mm, for example, when the sidewall portion bends when passing over a rim stone, a convex rib is arranged between the bent portion and the rim flange. Therefore, the impact can be mitigated by the convex rib. As a result, the rim flange can be protected and the trauma resistance can be improved. Further, since the rubber volume can be suppressed as compared with the conventional rim protect bar, the weight of the tire can be reduced.

In the pneumatic tire of the present invention, the rubber thickness at the tip of the convex rib is preferably 1.0 mm or more. As a result, the strength of the tip of the convex rib can be sufficiently ensured.

It is preferable that the rubber thickness of the convex rib gradually increases from the tip portion to the root portion. Thereby, the releasability of the convex rib at the time of manufacturing can be improved.

The ratio A / B of the rubber thickness A at the tip to the rubber thickness B at the root of the convex rib is preferably 0.2 to 0.5. As a result, the rigidity of the convex rib can be sufficiently ensured, and an excessive increase in mass can be suppressed.

The convex rib has a bent portion between the tip portion and the root portion, and the base portion forming from the bent portion to the root portion has a thicker rubber thickness than the tip portion, and the base portion with respect to the total length D of the convex rib. The length C of the rubber is preferably 30% to 35%. As a result, it is possible to suppress the movable range of the tip portion when assembling the rim and prevent the convex ribs from being caught.

The pneumatic tire is a pneumatic tire whose mounting direction with respect to the vehicle is specified, and it is preferable that the convex ribs are arranged only on the outside of the vehicle. As a result, the weight of the tire can be reduced.

Each dimension in the present invention is measured with the tire assembled on a regular rim and filled with a regular internal pressure. A "regular rim" is a rim defined for each tire in a standard system including a standard on which a tire is based. For example, a standard rim for JATTA, a "Design Rim" for TRA, or ETRTO. If so, it is set to "Measuring Rim". "Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. For JATTA, the maximum air pressure, and for TRA, the table "TIRE LOAD LIMITED AT VARIOUS". The maximum value described in "COLD INFLATION PRESSURES", and in the case of ETRTO, it is "INFLATION PRESSURE".

It is a meridian half cross-sectional view which shows the state which the pneumatic tire which concerns on embodiment of this invention is assembled to a standard rim. FIG. 5 is an enlarged cross-sectional view showing a convex rib provided on the pneumatic tire of FIG. 1. FIG. 5 is an enlarged cross-sectional view showing a convex rib provided on the pneumatic tire of FIG. 1. It is explanatory drawing which shows the state which the sidewall portion of the pneumatic tire which concerns on embodiment of this invention is bent. It is a meridian cross-sectional view which shows the modification of the pneumatic tire which concerns on embodiment of this invention.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show an example of a pneumatic tire according to an embodiment of the present invention.

As shown in FIG. 1, the pneumatic tire of the present embodiment includes a tread portion 1 extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions 2 arranged on both sides of the tread portion 1, and these. It includes a pair of bead portions 3 arranged inside the sidewall portion 2 in the tire radial direction. In FIG. 1, only a half cross section on one side in the tire width direction with the tire center line CL as a boundary is depicted, but this pneumatic tire has a symmetrical structure on both sides of the tire center line CL. .. Of course, it is also possible to adopt an asymmetric structure.

At least one carcass layer 4 formed by arranging a plurality of carcass cords in the radial direction is mounted between the pair of bead portions 3. As shown in the figure, when the carcass layer 4 is one layer, it is preferable from the viewpoint of weight reduction of the tire. Each end of the carcass layer 4 is wound around the bead core 5 arranged in each bead portion 3 from the inside to the outside of the tire, and the terminal 4e of the carcass layer 4 is arranged outside the bead core 5 in the tire radial direction. ing. In the carcass layer 4, the portion from the tread portion 1 through each sidewall portion 2 to each bead portion 3 is wound around the main body portion 4A and each bead portion 3 around the bead core 5 to the side of each sidewall portion 2. The portion extending toward the winding portion is called the winding portion 4B.

The bead core 5 has a wedge shape (outer diameter side wedge shape) that is convex toward the outside in the tire radial direction in a cross-sectional view of the meridian. Further, the bead core 5 is composed of at least one bead wire wound in the tire circumferential direction and an insulation rubber covering the bead wire. Further, the bead core 5 may include a bead cover and a wrapping thread arranged so as to bundle the bead wires.

In the pneumatic tire, the carcass layer 4 is wound around the bead core 5, but since the bead core 5 of the present invention has an outer diameter side wedge shape, the carcass layer 4 bends along the peripheral edge of the bead core 5. .. In the illustrated example, since the cross-sectional shape is substantially pentagonal, the carcass layer 4 extending along the peripheral edge thereof is also bent into a substantially pentagonal shape. Further, the portion of the winding portion 4B of the carcass layer 4 outside the bead core 5 in the tire radial direction extends toward each sidewall portion 2 side along the main body portion 4A while contacting the main body portion 4A of the carcass layer 4. doing. As a result, the main body portion 4A and the winding portion 4B of the carcass layer 4 form a closed region surrounding the bead core 5.

In the closed region surrounding the bead core 5, substantially only the bead core 5 exists, and a bead filler or a similar tire component as used in a conventional pneumatic tire (arranged outside the bead core 5 in the tire radial direction). A member that is wrapped by the main body portion 4A and the winding portion 4B of the carcass layer 4 to increase the rigidity from the bead portion 3 to the sidewall portion 2) is not arranged. That is, the bead filler used in the conventional pneumatic tire is not used in the closed region surrounding the bead core 5. With such a bead filler-less structure, the weight of the tire can be reduced.

On the other hand, a plurality of layers of belt layers 6 are embedded on the outer peripheral side of the tire of the carcass layer 4 in the tread portion 1. The belt layer 6 includes a plurality of reinforcing cords that are inclined with respect to the tire circumferential direction, and the reinforcing cords are arranged so as to intersect each other between the layers. In the belt layer 6, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set in the range of, for example, 10 ° to 40 °. As the reinforcing cord of the belt layer 6, for example, a steel cord is preferably used.

On the outer peripheral side of the tire of the belt layer 6, at least one belt reinforcing layer 7 formed by arranging the reinforcing cords at an angle of 5 ° or less with respect to the tire circumferential direction is arranged for the purpose of improving high-speed durability. There is. In FIG. 1, the belt reinforcing layer 7 located inside the tire radial direction constitutes a full cover layer covering the entire width of the belt layer 6, and the belt reinforcing layer 7 located outside the tire radial direction covers only both ends of the belt layer 6. It constitutes an edge cover layer to cover. As the reinforcing cord of the belt reinforcing layer 7, an organic fiber cord such as nylon or aramid is preferably used.

In the pneumatic tire, the convex rib 10 is provided at the position of the rim line of the sidewall portion 2. The convex rib 10 is an alternative to a general rim line. The convex rib 10 is a convex protrusion extending over the entire circumference in the tire circumferential direction, and exhibits an annular shape in a side view of the pneumatic tire T.

Here, the position of the rim line is within the range of 39% to 46% with respect to the height H in the tire radial direction from the position L2 of the bead heel 3h of the bead portion 3 to the maximum tire width position L1. That is, the convex rib 10 is arranged so that the entire convex rib 10 fits in the region S on the outer surface of the tire of the sidewall portion 2. In this case, the convex rib 10 does not come into contact with the rim flange Rf in a state where the pneumatic tire T is assembled to the standard rim R and filled with the maximum air pressure (for example, JATTA standard). The bead heel position L2 of the bead portion 3 is a position in the tire radial direction at the intersection P of the extension lines of the bead portion 3 which extends the contour line of the bead portion 3 connected to each of both ends of the bead heel 3h.

The convex rib 10 protrudes outward in the tire width direction from the outer surface of the tire of the sidewall portion 2 in a state where the pneumatic tire T is assembled to the standard rim R and filled with the maximum air pressure. Specifically, the convex rib 10 has a tip portion 11 which is the outermost portion in the tire width direction in the meridian cross section, and a root portion 12 which is the innermost portion in the tire width direction. The root portion 12 is also a boundary portion with the contour line 20 forming the outer surface of the tire from the sidewall portion 2 to the bead portion 3 (dotted line portion in the figure). A bent portion 13 is formed between the tip portion 11 and the root portion 12, and a base portion 14 is formed as a portion from the bent portion 13 to the root portion 12. The base portion 14 has a rubber thickness t thicker than that of the tip portion 11. The rubber thickness t is a rubber thickness measured along the tire radial direction.

In the examples of FIGS. 1 to 3, in the convex rib 10, the rubber thickness t in the tire radial direction gradually increases from the tip portion 11 to the root portion 12. Further, the tip portion 11 of the convex rib 10 is formed in an arc shape that is convex outward in the tire width direction. Further, the convex rib 10 has a pair of bent portions 13 between the tip portion 11 and the root portion 12, so that the rubber thickness t gradually increases from each bent portion 13 toward the root portion 12. The base 14 is formed.

Further, the convex rib 10 protrudes within a range of ± 5 ° with respect to the tire width direction. Preferably, the convex rib 10 protrudes along the tire width direction. In the example of FIG. 1, since the protruding direction of the convex rib 10 is parallel to the tire width direction, the inclination angle α (see FIG. 2) in the protruding direction is 0 °. The inclination angle α of the convex rib 10 in the protruding direction is an inclination angle of the center line X in the tire radial direction with respect to the tire width direction in the vicinity of the tip portion 11 of the convex rib 10. Further, the inclination angle α has a positive value of the inclination of the center line X outward in the tire radial direction with reference to the tire width direction, and a negative value of the inclination of the center line X inward in the tire radial direction.

Further, the tip portion 11 of the convex rib 10 is at the same position as the tip portion of the rim flange Rf in the tire width direction in a state where the pneumatic tire T is assembled to the standard rim R and filled with the maximum air pressure, or the rim. It projects outward from the tip of the flange Rf in the tire width direction. More specifically, the protrusion distance d between the tip end 11 of the convex rib 10 and the tip end portion of the rim flange Rf in the tire width direction is configured to be in the range of 0 mm to 10 mm. Preferably, the protrusion distance d is in the range of 3 mm to 7 mm. By ensuring an appropriate protrusion distance d in this way, for example, even if the sidewall portion 2 is bent when the pneumatic tire T gets over the curb, the convex rib 10 covers the rim flange Rf. be able to.

FIG. 4 shows a state in which the sidewall portion of the pneumatic tire according to the embodiment of the present invention is bent. When the pneumatic tire T gets over the curb, as shown in FIG. 4, the pneumatic tire T is crushed in the tire radial direction, and the sidewall portion 2 is in a bent state. At that time, at the bent portion of the sidewall portion 2, the sidewall portion 2 is completely bent and the inner surface of the tire is in close contact with the tire, and the bent portion protrudes outward in the tire width direction.

Even if the sidewall portion 2 is in a bent state as described above, since the convex rib 10 is arranged at the position of the rim line of the sidewall portion 2, between the bent portion and the rim flange Rf. The convex rib 10 will be arranged on the. That is, the convex rib 10 acts as a cushioning material between the bent portion and the rim flange Rf. As a result, when the pneumatic tire T gets over the curb, the impact on the pneumatic tire T can be mitigated.

In the above-mentioned pneumatic tire, since the convex rib 10 extending over the entire circumference in the tire circumferential direction is provided at the position of the rim line of the sidewall portion 2, the convex rib 10 replaces the general rim line. Can perform its function. Further, in a state where the pneumatic tire T is assembled to the standard rim R and inflated, the convex rib 10 extends within a range of ± 5 ° with respect to the tire width direction, and also extends with the tip portion 11 of the convex rib 10. Since the distance between the tip of the rim flange Rf and the tire width direction is 0 mm to 10 mm, for example, when the sidewall portion 2 bends when passing over a curb, the bent portion and the rim flange Rf The convex ribs 10 are arranged between them, and the impact can be alleviated by the convex ribs 10. Thereby, the rim flange Rf can be protected and the trauma resistance can be improved. Further, since the rubber volume can be suppressed as compared with the conventional rim protect bar, the weight of the tire can be reduced.

In the pneumatic tire, the rubber thickness A at the tip portion 11 of the convex rib 10 is preferably 1.0 mm or more. By appropriately setting the rubber thickness A of the tip portion 11 in this way, the strength of the tip portion 11 of the convex rib 10 can be sufficiently ensured. When the tip portion 11 of the convex rib 10 is formed in, for example, an arc shape or a polygonal shape, the portion formed in such a shape is not included in the rubber thickness A (see FIG. 3). ..

It is preferable that the rubber thickness t of the convex rib 10 gradually increases from the tip portion 11 toward the root portion 12 in the tire radial direction. In particular, the gradient β of the convex rib 10 (see FIG. 2) is preferably configured to be 2 ° to 5 ° with respect to the protruding direction of the convex rib 10. This means that the temperature is 2 ° to 5 ° with respect to the die drawing direction during tire molding. By configuring the convex rib 10 in this way, the releasability of the convex rib 10 at the time of manufacturing can be improved. The gradient β of the convex rib 10 is an inclination angle with respect to the protruding direction of the convex rib 10 on the contour line 10a forming the outer surface of the tire from the tip portion 11 to the bent portion 13. In FIG. 2, the protruding direction of the convex rib 10 is parallel to the tire width direction.

The ratio A / B of the rubber thickness A of the tip portion 11 to the rubber thickness B of the root portion 12 of the convex rib 10 is preferably 0.2 to 0.5. By appropriately setting the ratio A / B of the rubber thickness A and the rubber thickness B in this way, the rigidity of the convex rib 10 can be sufficiently ensured, and an excessive increase in mass can be suppressed. Can be done. The rubber thickness A of the tip portion 11 and the rubber thickness B of the root portion 12 (see FIG. 3) correspond to the rubber thickness t measured along the tire radial direction in each portion.

Here, if the ratio A / B is less than 0.2, the rigidity of the convex rib 10 cannot be sufficiently secured, and conversely, if the ratio A / B exceeds 0.5, the convex rib 10 It is not preferable because the mass becomes excessively large, which is disadvantageous for reducing the weight of the tire.

The convex rib 10 has a bent portion 13 between the tip portion 11 and the root portion 12, and the base portion 14 forming the bent portion 13 to the root portion 12 has a rubber thickness t thicker than that of the tip portion 11 and is convex. The length C of the base 14 with respect to the total length D of the rib 10 is preferably 30% to 35%. By appropriately setting the length C of the base portion 14 with respect to the total length D of the convex rib 10 in this way, the movable range of the tip portion 11 at the time of rim assembly is suppressed and the convex rib 10 is prevented from being caught. be able to.

The length C and the overall length D of the base portion 14 of the convex rib 10 are both measured along the protruding direction of the convex rib 10, that is, the tire diameter in the vicinity of the tip portion 11 of the convex rib 10. It is the length measured on the center line X of the direction (see FIG. 3). The length C of the base portion 14 is the length from the intersection of the line segment connecting the pair of bent portions 13 and the center line X to the root portion 12. In FIG. 3, the center line X of the convex rib 10 is parallel to the tire width direction.

FIG. 5 shows a modified example of the pneumatic tire according to the embodiment of the present invention. In FIG. 5, the pneumatic tire T is specified in the mounting direction with respect to the vehicle, IN indicates the inside of the vehicle, and OUT indicates the outside of the vehicle. As shown in FIG. 5, the convex rib 10 is arranged only on the sidewall portion 2 located on the outside of the vehicle. The convex rib 10 has a size and a shape satisfying the above-mentioned relational expression. By arranging the convex ribs 10 only on the outside of the vehicle in this way, it is possible to reduce the weight of the tire as compared with the case where the convex ribs 10 are arranged on both sides.

In the pneumatic tire according to the present invention, the convex rib 10 is not limited to the shape shown in FIGS. 1 to 3. For example, a convex rib 10 having no base 14 may be adopted. In this case, the convex rib 10 does not have the bent portion 13, the rubber thickness t gradually increases from the tip portion 11 to the root portion 12, and the same gradient β is maintained from the tip portion 11 to the root portion 12. Can have a shaped shape.

Further, in the above-mentioned pneumatic tire, in order to reduce the weight of the tire, an example of a bead filler-less structure having no bead filler used in a conventional pneumatic tire has been shown, but the present invention is not limited to this. Absent. The present invention can also be applied to a pneumatic tire having a bead structure in which a bead filler made of a rubber composition having a triangular cross section is arranged on the outer circumference of the bead core 5.

With a tire size of 205 / 55R16, a tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and these sidewall portions are arranged inside the tire radial direction. In a pneumatic tire provided with a pair of bead portions, the presence or absence of convex ribs, the distance between the tip portion and the rim flange, the protruding direction (inclination angle α with respect to the tire width direction), the rubber thickness A of the tip portion, and the convex shape. Rib gradient β, ratio of rubber thickness A at the tip to rubber thickness B at the root (A / B), presence / absence of a bent portion, ratio of base length C to total length D (C / D) × 100%) and the tires of Conventional Examples 1 and 2 and Examples 1 to 8 in which the arrangement locations on the vehicle were set as shown in Table 1 were manufactured.

In the conventional example 1, a conventional rim line is provided on the sidewall portion, and in the conventional example 2, a conventional rim protect bar is provided on the sidewall portion. Further, in Table 1, when the ratio of the base length C to the total length D is "0%", the convex rib does not have a bent portion. That is, the convex rib has a shape in which the rubber thickness gradually increases from the tip portion to the root portion and the same gradient is maintained from the tip portion to the root portion.

The tire mass and trauma resistance of these test tires were evaluated by the following test methods, and the results are also shown in Table 1.

Tire mass:
The mass per tire was measured for each test tire. The evaluation result is shown by an index with the value of Conventional Example 1 as 100 using the reciprocal of the measured value. The larger the index value, the lighter the tire mass, which means that it is superior in terms of weight reduction.

Trauma resistance:
A running test in which each test tire is assembled on a wheel with a rim size of 16 x 6.5J, mounted on a test vehicle with a displacement of 2000cc, and rides on a curb with a height of 110mm at an approach angle of 45 ° under the condition of an air pressure of 230kPa. Was carried out. Specifically, the initial speed was gradually increased from 10 km / h, and the speed at which the tire burst was measured. The evaluation result is shown by an index with Conventional Example 1 as 100. The larger the index value, the better the trauma resistance.

As can be seen from Table 1, the pneumatic tires of Examples 1 to 8 maintained the tire mass and the trauma resistance as compared with the conventional example 1.

On the other hand, in the conventional example 2, since the conventional rim protect bar is provided in the sidewall portion, the trauma resistance is improved, but the tire mass is deteriorated.

1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 10 Convex rib 11 Tip part 12 Root part 13 Bending part 14 Base part CL Tire center line R Rim Rf Rim flange T Pneumatic tire

Claims (6)

A tread portion extending in the tire circumferential direction to form an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged inside the tire radial direction of these sidewall portions. With pneumatic tires
A convex rib extending over the entire circumference in the tire circumferential direction is provided at the position of the rim line of the sidewall portion, and the convex rib is provided in the tire width direction with the tire assembled to the regular rim and filled with the regular internal pressure. A pneumatic tire characterized in that the distance between the tip of the convex rib and the tip of the rim flange in the tire width direction is 0 mm to 10 mm while protruding in a range of ± 5 °. The pneumatic tire according to claim 1, wherein the rubber thickness at the tip of the convex rib is 1.0 mm or more. The pneumatic tire according to claim 1 or 2, wherein the convex rib has a rubber thickness gradually increasing from a tip portion to a root portion. Any one of claims 1 to 3, wherein the ratio A / B of the rubber thickness A at the tip and the rubber thickness B at the root of the convex rib is 0.2 to 0.5. Pneumatic tires listed. The convex rib has a bent portion between the tip portion and the root portion, and the base portion forming from the bent portion to the root portion has a thicker rubber than the tip portion, and the entire convex rib. The pneumatic tire according to any one of claims 1 to 4, wherein the length C of the base with respect to the length D is 30% to 35%. The pneumatic tire according to any one of claims 1 to 5, wherein the pneumatic tire is a pneumatic tire whose mounting direction with respect to the vehicle is specified, and the convex ribs are arranged only on the outside of the vehicle. tire.

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