JP2014184916A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which is formed into a laterally asymmetric shape so as to further improve wear resistance while exerting excellent steering stability.SOLUTION: The present pneumatic tire is formed into a laterally asymmetric shape in which radial heights H1 and H2 of maximum width positions P1 and P2 from a tire equator face C to outer faces of a pair of side wall portions 4a and 4b are different between the side wall portions 4a and 4b. Only in one tire side portion 8a, in which the radial heights H1 and H2 of the maximum width positions P1 and P2 are relatively low, of the tire side portions 8a and 8b including the side wall portions 4a and 4b and the bead portion 2 is provided with a side reinforcement member 11. The side reinforcement member 11 is arranged in a radial region Ar including a radial position of a radial outer edge 7e of a bead filler 7.

Description

  The present invention relates to a pneumatic tire.

In recent years, for example, in passenger car tires, when mounted on a vehicle in a posture with a negative camber that is a mounting posture in which the road surface portion of each of the left and right tires in the front view of the vehicle faces the outside of the vehicle, For the purpose of improving steering stability performance, the tires are asymmetrical in the left-right asymmetric shape, with the dimensions of each sidewall portion located on the inside and outside of the vehicle, and the radius of curvature of the inner surface in the cross section in the width direction, etc. And that is done.
In this case, the tire equator plane including the center position of the rim width of the tire ground contact surface when the negative camber is applied, as exemplified by the footprint in FIG. By controlling the rectangular ratios Li / Lc and Lo / Lc, which are the ratios of the contact lengths Li and Lo at the 80% position of the maximum contact width W around the tire equatorial plane with respect to the contact length Lc at In addition to improved steering stability, it is possible to improve wear resistance.
In addition, it is described in patent document 1 etc. about making a tire into a left-right asymmetric shape here.

JP-A-8-230408

  However, even in the case of applying the asymmetric shape as described above, in the tire mainly used for straight traveling, the above-described rectangular ratio Li / Lc depends on only changes in the dimensions of both sidewall portions. , Lo / Lc cannot be controlled sufficiently, and when rolling with a load with a negative camber applied, the rectangular ratio of the tread surface, especially as shown in FIG. However, since the ground contact area in the outer tread area of the vehicle could not be increased as much as the inner tread area, the tread tread could not be evenly worn between the inner side and the outer side of the vehicle.

  The object of the present invention is to solve such problems of the prior art, and the object of the invention is to exhibit excellent steering stability performance by making the tire asymmetrical to the left and right. On the other hand, it is an object of the present invention to provide a pneumatic tire that can further improve the wear resistance.

  The pneumatic tire according to the present invention includes a bead core embedded in each of a pair of bead portions, a toroid-shaped main body portion extending from the tread portion to each bead portion through each sidewall portion, and continuous to the main body portion. One or more carcass plies each having a folded portion formed around each of the bead cores, and the carcass ply main body portion and each folded portion on the outer side in the tire radial direction of each bead core. A pair of bead fillers sandwiched between the radial heights of the maximum width position where the length measured from the tire equator surface to the outer surface of each sidewall portion along the tire width direction is the maximum. The pair of sidewall portions have different asymmetric shapes, and the sidewall portions and the bead portions A side reinforcing member is provided only in one of the tire side portions including a tire side portion having a relatively low radial height at the maximum width position, and the side reinforcing member is connected to a radially outer end of the bead filler. Are arranged in a radial region including the radial position.

In the present invention, the above-mentioned “radial height” and other distances, lengths, and the like are measured in an unloaded state in which the tire is assembled to the applied rim and filled with the specified internal pressure.
Here, “applicable rim” refers to a standard rim defined in the following standard or Design Rim or Measuring Rim according to the tire size, and “specified internal pressure” refers to the maximum load capacity in the following standard. The “maximum load capacity” means the maximum mass allowed to be loaded on the tire according to the following standards. The standard is determined by an industrial standard effective in the region where tires are produced or used. For example, in the United States, “THE TIRE AND RIM ASSOCIATION INC. YEAR BOOK” is used in Europe. "The European Tire and Rim Technical Organization's STANDARDDS MANUAL", and in Japan, the Japan Auto Tire Association's JATMA YEAR BOOK.

  The “tire equatorial plane” referred to in the present invention includes the center position of the rim width in a posture in which the tire is assembled to the applied rim and the camber angle is not applied under a no-load state filled with the specified internal pressure. It shall mean a plane parallel to the radial direction.

  In the pneumatic tire according to the present invention, the side reinforcing member includes an organic fiber cord or a steel cord, or a high-hardness rubber material having a rubber hardness larger than that of the side rubber provided on the tire side portion. It is preferable to embed the carcass ply on the outer side in the tire width direction.

  In the pneumatic tire of the present invention, the side reinforcing member is made of a rubber material, and the side reinforcing member is disposed on the inner side in the tire width direction of the carcass ply. It is also preferable that the thickness is gradually reduced toward the inner side and the outer side in the radial direction.

According to the pneumatic tire of the present invention, the side reinforcing member is provided only on one tire side portion having a relatively low radial height at the maximum width position, and the side reinforcing member is disposed outside the bead filler in the radial direction. By arranging in the radial region including the radial position of the end, the rigidity at the other tire side portion is relatively lower than that at the one tire side portion. One tire side part with a low radial direction at a large position is positioned inside the vehicle, and the other tire side part with relatively low rigidity is greatly deformed in a mounting posture provided with a negative camber. The ground contact area of the tread area on the tire side portion side can be made closer to that of the tread area on the one tire side portion side.
As a result, the aforementioned rectangular ratio can be optimized, and the wear resistance can be greatly enhanced.

  In addition, this tire has the above-mentioned mounting posture on the vehicle by making the height in the radial direction of the maximum width position from the tire equatorial plane to the outer surface of the sidewall portion different from each other between the pair of sidewall portions. , Can exhibit excellent steering stability performance.

  Here, the side reinforcing member is made of an organic fiber cord or a steel cord, or a high hardness rubber material having a rubber hardness larger than that of the side rubber provided on the tire side portion, and the side reinforcing member is attached to the carcass ply. When embedded in the outer side in the tire width direction, the side reinforcing member is disposed outside the carcass ply, and thus has a role of protecting the carcass ply when the tire side portion is damaged.

  On the other hand, the side reinforcing member made of a rubber material is disposed on the inner side in the tire width direction of the carcass ply, and the thickness is increased toward the inner side and the outer side in the tire radial direction within the cross section in the tire width direction. When the shape is gradually reduced, the side reinforcing member is positioned in a region that receives the compression input when the tire side portion is deformed and exhibits a reaction force against the compression input. Therefore, one tire provided with the side reinforcing member The effect of suppressing the bending deformation of the side portion is further exerted, and therefore, the deformation difference from the bending deformation of the other tire side portion can be further increased. Alternatively, the same effect can be expected with a small amount of side reinforcing members and a side reinforcing member with low hardness.

1 is a schematic cross-sectional view along the tire width direction showing an embodiment of a pneumatic tire of the present invention. It is sectional drawing similar to FIG. 1 which shows other embodiment of the pneumatic tire of this invention. It is a figure which shows the footprint of the tire of FIG. It is a figure which shows the footprint of the conventional tire.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
A tire 1 shown in FIG. 1 includes a bead core 3 embedded in each of a pair of bead portions 2, a main body portion 6a extending from each bead portion 2 to each of the tread portions 5 through the sidewall portions 4a and 4b, and At least one carcass ply 6 having a folded portion 6b that is folded around each bead core 3 in succession to the body portion 6a, in the figure, one carcass ply 6 and on the outside of each bead core 3 in the tire radial direction, A bead filler 7 is disposed between the main body portion 6a and the folded portion 6b and has a shape in which the thickness is gradually reduced toward the outer side in the tire radial direction. Here, the bead portion 2 and the sidewall portions 4a or 4b are referred to as tire side portions 8a or 8b.

  Here, the carcass ply 6 that can have a radial structure in which a plurality of cords made of steel or organic fiber are extended in the radial direction has a tire width around the bead core 3 as shown in FIG. The folded portion 6b folded from the inner side toward the outer side is extended along the outer surface of the main body portion 6a on the outer side in the tire radial direction with respect to the region where the bead filler 7 is disposed, and the folded end portion is extended to the carcass ply. 6 is disposed so as to be sandwiched between the body portion 6a and the outer portion in the width direction of the belt 9 composed of the three belt layers 9a, 9b, 9c disposed on the outer peripheral side of the crown region.

The belt layers 9a to 9c that can be provided in one layer, two layers, or four layers or more are made of, for example, one or more steel cords or organic fiber cords that are inclined at a required angle with respect to the tire circumferential direction. It can be an inclined belt layer. In this case, the cords can extend in opposite directions with respect to the tire circumferential direction between the inclined belt layers adjacent inside and outside in the tire radial direction.
Further, at least one of the belt layers 9a to 9c is configured by extending a rubber strip in which one or a plurality of cords are embedded in the tire circumferential direction and winding the rubber strip spirally in the tire width direction. The cord of the spiral belt layer configured as described above may extend substantially along the tire circumferential direction at an angle of, for example, 5 ° or less with respect to the tire circumferential direction. become.

  Here, in the tire 1, the maximum width position where the length measured along the tire width direction from the tire equatorial plane C to the outer surfaces of the sidewall portions 4a and 4b is the maximum, except for the rim guard arrangement area. P1 and P2 are the heights H1 and H2 in the radial direction from the innermost point Ip in the radial direction of the tire 1 (the tip of the bead toe in the illustrated tire 1). The tire 1 is asymmetric with respect to the tire equatorial plane C as different wall portions 4a and 4b.

  According to this, in the illustrated embodiment, the radial height H1 of the maximum width position P1 in one tire side portion 8a (right tire side portion in the figure) is set to the other tire side portion 8b (left side in the figure). When the tire 1 is mounted on the vehicle, the one tire side portion 8a is positioned on the inner side of the vehicle by relatively lower than the radial height H2 of the maximum width position P2 in the tire side portion). For example, in a state where a negative camber of about −1 ° is provided, the steering stability performance can be greatly improved as compared with the case where the radial heights of the maximum width positions at both tire side portions are equal to each other.

The ratio H1 / H2 of the radial height H1 of the maximum width position P1 in one tire side portion 8a to the radial height H2 of the maximum width position P2 in the other tire side portion 8b is 0. It is preferable to set it to 85-0.95 from a viewpoint of exhibiting the outstanding steering stability performance.
Similarly, the ratio R1 / R2 of the radius of curvature R1 of the tire inner surface at one tire side portion 8a to the radius of curvature R2 at the other tire side portion 8b is 1.5 to 2.5. It is preferable from the viewpoint.

  Here, in the illustrated tire 1, the above-mentioned radial height H1 is 60 mm and the radius of curvature of the tire inner surface in one tire side portion 8a in an unloaded state in which the tire 1 is assembled to the applicable rim and filled with the specified internal pressure. R1 is 130 mm. On the other hand, the radial height H2 of the other tire side portion 8b is 70 mm, and the radius of curvature R2 of the tire inner surface is 60 mm.

By the way, even in the case of the tire 1 having the left-right asymmetric shape in this way, in the mounting posture provided with the negative camber, the tread formed on the outer peripheral side by the tread rubber 10 disposed on the outer peripheral side of the belt 9 described above. It is difficult to ground the tread surface uniformly in the entire width direction, so that the wear resistance performance cannot be improved as much as expected.
In contrast, in the present invention, of the tire side portions 8a and 8b, the side reinforcing member 11 is attached only to the tire side portion 8a which has a low radial height at the maximum width position and is positioned inside the vehicle. The side reinforcing member 11 is disposed in a radial region Ar including the radial position of the radially outer end 7 e of the bead filler 7.

In particular, in the tire 1 shown in FIG. 1, while extending in the tire radial direction, the thin annular annular side reinforcing member 11 extending over the entire circumference of the tire 1 is used as both the main body portion 6a and the folded portion 6b of the carcass ply 6. For example, along the outer surface of the folded portion 6b of the carcass ply 6 on the outer side in the width direction, it is embedded in one tire side portion 8a.
As the side reinforcing member 11, for example, an organic fiber cord or a steel cord extending at a required angle with respect to the tire circumferential direction, or a material having a high hardness rubber material having a rubber hardness higher than that of the side rubber 12 provided on the tire side portion is used. be able to.

By providing such a side reinforcing member 11 only on one tire side portion 8a, the rigidity of the other tire side portion 8b on which the side reinforcing member 11 is not provided is relatively relative to the one tire side portion 8a. From the fact that the lower tire side portion 8b is deformed more greatly than the one tire side portion 8a due to the action of the contact pressure on the tread surface, the tire equatorial surface C of the tread tread surface is lower. In addition, the ground contact area of the tread area on the other tire side portion 8b side is increased.
Therefore, FIG. 3 shows a footprint under conditions in which a load corresponding to 88% of the maximum load capacity is applied with a negative internal camber attached to the applicable rim and filled with a specified internal pressure. As in the case of the tire ground contact surface, the rectangular ratio Lo / Lc outside the vehicle is higher than that of the conventional tire ground contact surface under the same conditions as shown in FIG. Thus, the entire tread surface can be grounded uniformly, and the wear resistance can be greatly enhanced.

The reason for disposing the side reinforcing member 11 in the radial region Ar including the radial position of the radially outer end 7e of the bead filler 7 is the tire side portion 8a, which is generally made of a rubber material with high hardness. The bead filler 7 is reinforced with the side reinforcing member 11 from the vicinity of the radially outer end 7e where the rigidity is smaller than that in the vicinity of the bead core 3 in the vicinity of the bead core 3. This is to prevent the portion 8a from being formed with a portion where the rigidity greatly changes locally in the tire radial direction.
In other words, when the side reinforcing member is disposed in a radial region that does not include the radial position of the radially outer end of the bead filler, the rigidity of the sidewall portion is between the bead filler and the side reinforcing member. Will greatly change, and it is undeniable that the durability is lowered due to an increase in strain.

  Here, the radial region Ar in which the side reinforcing member 11 is disposed is the difference between the outer diameter of the tire and the rim diameter with the radial position of the radial outer end 7e of the bead filler 7 as the center in the illustrated cross section in the width direction. It is preferable to set it to 8% to 40% of the tire cross-sectional height which is 1/2 of this. Also in the case of measuring the range of the radial region Ar, the tire 1 is assembled to the applicable rim and is loaded in a no-load state filled with the specified internal pressure.

  Here, the maximum thickness of the side reinforcing member 11 along the normal line standing on the surface thereof is preferably 10% to 40% of the total thickness of the tire side portion 8a, and according to this, A tire can be manufactured while preventing a level difference from occurring between a portion where the side reinforcing member 11 is disposed and a portion where the side reinforcing member 11 is not disposed. This maximum thickness of the side reinforcing member 11 can be, for example, 0.7 mm to 1.0 mm in the above-described unloaded state.

  In addition, when the side reinforcing member 11 is composed of an organic fiber cord or a steel cord, the side reinforcing member 11 has such a side reinforcing member 11 that greatly increases the rigidity of the one tire side portion 8a. It is preferable to extend at an angle in the range of 30 ° to 45 ° with respect to the tire circumferential direction. Note that the cord constituting the side reinforcing member 11 can be bent or curved at least at one part or at one place in the middle of the extension, but when the cord is curved and extends, The angle is obtained by measuring the tangent angle of the cord at an arbitrary position in a side view of the tire under a no-load state in which the tire 1 is assembled to the applicable rim and filled with the specified internal pressure.

  On the other hand, when the side reinforcing member 11 is made of a high hardness rubber material, the hardness of the high hardness rubber material can be 1.4 to 2 times the hardness of the side rubber 12, more specifically. The hardness of this high-hardness rubber material can be set to 70 to 98 in terms of JIS A hardness measured with a type A durometer in an environment of 25 ° C. in accordance with the provisions of “JIS-K6253”. As the hardness of the side reinforcing member 11 is higher, a difference in rigidity between the tire side portions 8a and 8b on both sides can be more effectively generated, and a performance tuning effect can be expected. In addition, when the hardness of the side reinforcing member 11 is too low, there is a tendency that it is difficult to cause a difference in rigidity between the tire side portions 8a and 8b on both sides.

  Here, in order to sufficiently improve both the steering stability performance and the wear resistance performance, the rectangular ratio Li / inside the vehicle on the tire contact surface shown in FIG. It is preferable to determine the size and shape of each tire side portion 8a, 8c and the form of the side reinforcing member 11 so that the ratio of the rectangular ratio Lo / Lc outside the vehicle to Lc is 97-100. .

Another embodiment illustrated in FIG. 2 has the same configuration as the tire 1 of FIG. 1 except that the arrangement position and the cross-sectional shape of the side reinforcing member are changed.
More specifically, in the tire 1 shown in FIG. 2, at one tire side portion 8 a located on the inner side of the vehicle, on the inner side in the tire width direction of the carcass ply 6, on the outer side in the tire radial direction in the illustrated cross section in the width direction A side reinforcing member 21 made of a rubber material having a substantially crescent shape in which the thickness is gradually reduced in a curved shape that protrudes outward in the tire width direction is provided as it goes toward the inside.
This side reinforcing member 21 is formed of one tire side portion 8a, for example, from a body portion 6a of the carcass ply 6 and an air-impermeable rubber material that is disposed inside the carcass ply 6 and forms the tire inner surface. Between the inner liner 13 and the inner liner 13.

Even with such a crescent-shaped side reinforcing member 21, the rigidity of the other tire side portion 8b can be relatively lowered with respect to the one tire side portion 8a having increased rigidity. As described above with respect to the first tire 1, the wear resistance can be significantly improved.
The side reinforcing member 21 shown in FIG. 2 is a rubber material having a hardness higher than that of the side rubber 12, preferably 1.2 to 1.8 times the hardness of the side rubber 12 as measured by the JIS A hardness. It can be composed of a rubber material having a hardness within the range.

  Next, a pneumatic tire according to the present invention was prototyped and its performance was evaluated, which will be described below. In all the test tires, the tire size was 205 / 55R16.

Here, the Example tire 1 has the structure shown in FIG. 1, and a rubber material having a hardness higher than that of the side rubber is used as the side reinforcing member. In addition, the Example tire 2 has the structure shown in FIG. 2, and a rubber material having a hardness higher than that of the side rubber is used as the side reinforcing member.
On the other hand, the comparative example tire 1 has a structure similar to that of the example tire 1 except that the tire shape is symmetrical and the side reinforcing rubber is not provided. The comparative example tire 2 has the same structure as the example tire 1 except that the tire shape is symmetrical, and the comparative example tire 3 is provided with no side reinforcing member. The tire had the same structure as that of Example Tire 1.

  Each of these test tires was assembled into a rim of size 16-6.5J, filled with an internal pressure of 180 kPa, and in a posture with a camber of -1 ° applied under a load of 5.3 kN. In addition to calculating the ratio of the ratio of the rate to the outside of the vehicle, the test was performed by mounting the vehicle on the vehicle to evaluate the wear resistance. The results are shown in Table 1 together with the specifications of each test tire. The index value of the wear resistance shown in Table 1 uses the comparative tire 1 as a control, and the higher the value, the better the wear resistance.

As is clear from the results shown in Table 1, the tires 1 and 2 in which the tire shape is left-right asymmetric and the side reinforcing member is provided are rectangular ratios compared to the comparative example tire 3 in which the side reinforcing member is not provided. However, they are equal on the inside and outside of the vehicle and exhibit excellent wear resistance.
Therefore, according to the pneumatic tire of the present invention, it was found that the wear resistance can be greatly improved.

1 tire; 2 bead part; 3 bead core; 4a, 4b sidewall part; 5 tread part; 6 carcass ply; 6a carcass ply body part; 6b carcass ply folded part; 7 bead filler; End: 8a, 8b Tire side part; 9 Belt; 9a, 9b, 9c Belt layer; 10 Tread rubber; 11 Side reinforcing member; 12 Side rubber; 13 Inner liner; C Tire equatorial plane; P1, P2 Maximum width of the sidewall part Position; H1, H2 Radial height of maximum width position; Ar Radial area where side reinforcing member is arranged; R1, R2 Radius of curvature of tire inner surface; Lc Ground contact length at center position in width direction of tire ground contact surface; W Maximum contact width of tire contact surface; Li, Lo Contact length at 80% of maximum contact width

Claims (3)

Each bead core embedded in each of the pair of bead portions, a toroidal main body portion that reaches each bead portion from the tread portion through each sidewall portion, and each of the bead cores continuously to the main body portion. One or more carcass plies each having a folded portion that is folded around, and a pair of beads arranged sandwiched between the main body portion of the carcass ply and the folded portions outside the bead core in the tire radial direction. A pneumatic tire comprising a filler,
The height in the radial direction of the maximum width position where the length measured along the tire width direction from the tire equator plane to the outer surface of each sidewall portion is the maximum, and the pair of sidewall portions have different asymmetric shapes,
Of the tire side parts including the sidewall part and the bead part, a side reinforcing member is provided only on one tire side part having a relatively low radial height at the maximum width position, and the side reinforcing member is A pneumatic tire, which is disposed in a radial region including a radial position of a radially outer end of the bead filler.   The side reinforcing member includes an organic fiber cord or a steel cord, or a hard rubber material having a hardness higher than that of the side rubber provided on the tire side portion, and the side reinforcing member is disposed outside the carcass ply in the tire width direction. The pneumatic tire according to claim 1, which is embedded in the tire.   The side reinforcing member is made of a rubber material, and the side reinforcing member is disposed on the inner side in the tire width direction of the carcass ply and is directed toward the inner side and the outer side in the tire radial direction in the cross section of the tire width direction. The pneumatic tire according to claim 1, wherein the pneumatic tire has a shape with a gradually reduced thickness.

Images