JP2014201203A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which improves stable steering performance by securing sufficient rigidity using a bead reinforcing layer, and also improves load durability performance by thoroughly securing a flexible zone on a side wall part.SOLUTION: A bead reinforcing layer, in a cross-sectional view in a tire radial direction and a tire width direction, has a first inflection point at least at a tire radial position, and in a cross-sectional view in a tire circumferential direction and the tire width direction, has a second inflection point at least at two tire circumferential positions. A plurality of unit surfaces, which are partitioned by sectioned and formed by a surface circumferential line segment extending in the tire circumferential direction while moving at least in either of the tire radial direction and the tire width direction from the first inflection point, and a surface radial line segment extending in the tire radial direction while moving at least in either of the tire circumferential direction and the tire width direction from the second inflection point, are formed on the surface of the bead reinforcing layer. Through-holes are formed in the unit surfaces.

Description

  The present invention relates to a pneumatic tire including a bead reinforcement layer.

  Conventionally, a pneumatic tire provided with a bead reinforcement layer is known (for example, refer to patent documents 1). The technique disclosed in Patent Document 1 includes a bead reinforcement layer made of a cord concentrically arranged with a bead core, a longitudinal wave portion that is uneven in the radial direction of the spiral, and an unevenness in a direction perpendicular to the radial direction of the spiral. This is a technique formed so as to include a transverse wave portion.

JP 2004-58685 A

  In the technique disclosed in Patent Document 1, since the bead reinforcement layer is composed only of a cord, the rigidity at the location where the bead reinforcement layer is disposed is not sufficient. For this reason, in order to ensure steering stability performance, it is necessary to provide the bead reinforcing layer over a wide range in the tire radial direction.

  Further, in the technique disclosed in Patent Document 1, since the bead reinforcement layer is formed over a wide range in the tire radial direction, there is a possibility that a flexible flex zone that is rich in flexibility cannot be secured in the sidewall portion. It is unclear whether can be realized.

  The present invention has been made in view of the above circumstances, and by using a bead reinforcement layer to sufficiently ensure rigidity, it improves steering stability performance and sufficiently secures a flex zone in the sidewall portion. An object of the present invention is to provide a pneumatic tire with improved load durability.

  The pneumatic tire according to the present invention is disposed outside the bead core in the tire radial direction, and is disposed along a bead filler disposed between a main body portion and a winding portion of the carcass ply and an extending direction of the bead filler. And it is a pneumatic tire provided with the bead reinforcement layer extended cyclically | annularly in a tire peripheral direction. In the tire radial direction and tire width direction cross-sectional view, the bead reinforcing layer has a first bending point at at least one position in the tire radial direction position. Moreover, the bead reinforcement layer has a second bending point at at least two positions in the tire circumferential direction when viewed in the tire circumferential direction and the tire width direction cross-sectional view. And on the surface of the bead reinforcement layer, a surface circumferential direction line segment extending in the tire circumferential direction while fluctuating in at least one direction of the tire radial direction and the tire width direction from the first bending point, and the second A plurality of unit surfaces are formed that are partitioned by a surface radial direction line segment extending in the tire radial direction while changing in at least one direction of the tire circumferential direction and the tire width direction from the bending point. Further, a through hole is formed on the unit surface.

  In the pneumatic tire according to the present invention, the bead reinforcing layer has a three-dimensional structure defined by a plurality of bending points appearing on two cross sections, and is partitioned by line segments having these bending points as the start point and the end point. Through-holes are formed in the unit surface. As a result, the steering stability performance is improved by sufficiently securing rigidity due to the presence of the bead reinforcing layer having the three-dimensional structure, and the load durability performance is improved by sufficiently securing the flex zone in the sidewall portion.

FIG. 1 is a tire meridian cross-sectional view showing a region from a bead portion to a sidewall portion of a pneumatic tire according to an embodiment of the present invention. 2 is a perspective view showing the bead reinforcement layer 30 of FIG. 1, in which (a) is an example in which a surface circumferential direction line segment and a surface radial direction line segment are configured by straight lines, and (b) is a surface circumference. This is an example in which the direction line segment and the surface radial direction line segment are configured by curves. 3A and 3B are diagrams showing the bead reinforcing layer 301 shown in FIG. 2A, FIG. 3A is a sectional view in the tire radial direction and the tire width direction, and FIG. 3B is the tire circumferential direction and the tire width direction. It is a part of sectional drawing. 4 shows the surface circumferential direction segments x1, x2, x3, x4 and the surface radial direction segments y2, y3, y4 appearing on the surface of the bead reinforcement layer 301 shown in FIG. It is a figure which shows the bending angle of the projected surface projection line segment. 5A and 5B are diagrams showing the bead reinforcing layer 302 shown in FIG. 2B, wherein FIG. 5A is a sectional view in the tire radial direction and the tire width direction, and FIG. 5B is the tire circumferential direction and the tire width direction. It is a part of sectional drawing. 6 shows surface circumferential direction line segments x5, x6, x7, x8 and surface radial direction line segments y7, y8, y9 appearing on the surface of the bead reinforcement layer 302 shown in FIG. It is a figure which shows the bending angle of the projected surface projection line segment. FIG. 7 is a partial perspective view of the bead reinforcing layer 301 showing the enlarged circled portion shown in FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a pneumatic tire according to the present invention (basic forms and additional forms 1 to 5 shown below) will be described in detail with reference to the drawings. Note that these embodiments do not limit the present invention. In addition, the constituent elements of the above embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. Furthermore, various forms included in the above-described embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Basic form]
Below, the basic form is demonstrated about the pneumatic tire which concerns on this invention. In the following description, the tire radial direction means a direction orthogonal to the rotational axis of the pneumatic tire, the tire radial inner side is the side toward the rotational axis in the tire radial direction, and the tire radial outer side is in the tire radial direction. The side away from the rotation axis. The tire circumferential direction refers to a circumferential direction with the rotation axis as a central axis. Further, the tire width direction refers to a direction parallel to the rotation axis, the inner side in the tire width direction is the side toward the tire equatorial plane CL in the tire width direction, and the outer side in the tire width direction is the tire equatorial plane CL in the tire width direction. The side away from. The tire equatorial plane CL is a plane that is orthogonal to the rotational axis of the pneumatic tire and passes through the center of the tire width of the pneumatic tire. In addition, in the following description, the tire radial direction and tire width direction cross section means a plane determined by two axes of an axis extending in the tire radial direction and an axis extending in the tire width direction, and the tire circumferential direction And the tire width direction cross section means a plane defined by two axes of an axis extending in the tire circumferential direction and an axis extending in the tire width direction.

  FIG. 1 is a tire meridian cross-sectional view showing a region from a bead portion to a sidewall portion of a pneumatic tire according to an embodiment of the present invention. That is, the region shown in the figure is a region including a bead portion 10 on one side in the tire width direction and a sidewall portion 20 extending outward from the bead portion 10 in the tire radial direction. The sidewall portion 20 further includes a sidewall portion on the other side in the tire width direction that sequentially extends from the tread portion to the inside in the tire radial direction via a tread portion (not shown) extending outward in the tire radial direction. It is connected to a bead part (neither is shown). That is, in the pneumatic tire 1 according to the embodiment of the present invention, a pair of sidewall portions and a pair of bead portions are continuously formed around the tread portion in the tire meridian cross-sectional view. And a pair of bead part, a pair of side wall part, and a tread part are continuously extended in the tire peripheral direction, respectively, and the pneumatic tire 1 has comprised the toroidal shape as a whole.

  A bead core 12 having a ring shape extending in the tire circumferential direction is disposed in the bead portion 10. The bead core 12 is formed, for example, by bundling a plurality of bead wires made of high carbon steel, and the tire meridional cross-sectional shape of the bead core 12 can be selected from various shapes such as a quadrangle, a hexagon, and a circle.

  Further, in the region from the bead portion 10 to the tread portion (not shown) via the sidewall portion 20, at least one carcass ply 14 with a reinforcing ply cord embedded therein, as shown in FIG. It is installed. The carcass ply 14 is wound around the bead core 12 from the inner side in the tire width direction toward the outer side in the vicinity of the innermost end (end portion) in the tire radial direction, and the upper winding portion 14b on the outer side in the tire width direction with respect to the main body portion 14a. Is formed. Thus, since the carcass ply 14 is disposed in close contact with the bead core 12 in the vicinity of the end portion, the carcass ply 14 is separated from the bead core 12 due to the bending of the sidewall portion 20 or the tire filling air pressure. The carcass ply 14 does not easily deviate from the bead core 12 even when force is applied.

  The ply cord that is a component of the carcass ply 14 may extend at any angle with respect to the circumferential direction of the tire. The material of the ply cord can be selected from various materials, for example, organic fiber such as aramid, polyethylene and nylon, glass fiber, steel, and materials having rigidity equivalent to these. Can do.

  Further, the bead portion 10 is provided with a reinforcing layer 16 in which a reinforcing cord is embedded. The reinforcing layer 16 is a layer for preventing the carcass ply 14 from being worn when the pneumatic tire 1 rubs against a rim flange (not shown) during load rolling. The reinforcing layer 16 is disposed in close contact with the outer side in the tire width direction of the carcass ply 14 so as to cover a part of the winding portion 14b of the carcass ply 14. Thus, since the reinforcing layer 16 is disposed in close contact with the carcass ply 14, it is possible to suppress shear strain and circumferential strain in the reinforcing layer 16, particularly in the close contact portion.

  The reinforcing cord of the reinforcing layer 16 may extend at any angle with respect to the circumferential direction of the tire. Various materials can be selected for the reinforcing cord. For example, organic fibers such as aramid, polyethylene and nylon, glass fiber, steel, and materials having the same rigidity can be selected. it can.

  In addition, in the region outside the bead core 12 in the tire radial direction and between the main body portion 14a and the winding portion 14b of the carcass ply 14, the fall of the bead portion 10 due to the bending of the sidewall portion 20 is suppressed. For this purpose, a bead filler 18 is provided. The bead filler 18 is formed of a rubber material having a hardness higher than that of the surrounding rubber member. The tire meridian cross-sectional shape of the bead filler 18 is a substantially triangular shape that gradually decreases in thickness toward the outer side in the tire radial direction. Thus, by making the bead filler 18 into a substantially triangular shape in the tire meridional section, the rigidity gradually decreases from the inner side to the outer side in the tire radial direction, and the occurrence of shear strain due to the rigidity step in this direction is suppressed. be able to.

  Under such a premise, in the present embodiment, a bead reinforcing layer 30 is disposed along the extending direction of the bead filler 18 as shown in FIG. The bead reinforcing layer 30 extends annularly in the tire circumferential direction.

  FIG. 2 is a perspective view showing the bead reinforcing layer 30 of FIG. 1, and (a) is an example (type 1) in which the surface circumferential direction line segment and the surface radial direction line segment are configured by straight lines, and (b) ) Is an example (type 2) in which the surface circumferential direction line segment and the surface radial direction line segment are configured by curves. The bead reinforcing layers 30 (301, 302) shown in FIG. 2 are all made of metal materials such as carbon steel, stainless steel and aluminum alloy, and fiber reinforced such as CFRP (Carbon Fiber Reinforced Plastics) and GFRP (Glass Fiber Reinforced Plastics). It can be formed of plastic and a material that exhibits the same rigidity as these materials.

  3A and 3B are diagrams showing the bead reinforcing layer 301 (type 1) shown in FIG. 2A. FIG. 3A is a sectional view in the tire radial direction and the tire width direction, and FIG. 3B is the tire circumferential direction. And it is a part of tire width direction sectional drawing. 3B shows only a specific region in the tire circumferential direction of the bead reinforcing layer 301, the bead reinforcing layer 301 is further in the tire circumferential direction than both ends in the illustrated tire circumferential direction. It extends to both sides of the direction and forms a ring.

  As shown in FIG. 3 (a), the bead reinforcing layer 301 has at least one position in the tire radial direction in the tire radial direction and in the tire width direction sectional view, and four places as shown in FIG. It has points X1, X2, X3, X4. The corresponding portions of the first bending points are clearly shown in FIG.

  Similarly, as shown in FIG. 3 (b), the bead reinforcement layer 301 has at least two positions in the tire circumferential direction in the tire circumferential direction and the tire width direction cross-sectional view. At five locations, second bending points Y1, Y2, Y3, Y4, and Y5 are provided. The corresponding portions of the second bending points are clearly shown in FIG.

  As shown in FIG. 2 (a), on the surface of the bead reinforcing layer 301, the tire is changed from the first bending points X1, X2, X3, and X4 in at least one direction of the tire radial direction and the tire width direction. Surface circumferential direction line segments x1, x2, x3, x4 extending in the circumferential direction are formed. Similarly, the surface of the bead reinforcement layer 301 extends from the second bending points Y1, Y2, Y3, Y4, Y5 in the tire radial direction while fluctuating in at least one direction of the tire circumferential direction and the tire width direction. Radial line segments y1, y2, y3, y4, and y5 are formed. As a result, a plurality of unit surfaces S are formed on the surface of the bead reinforcement layer 301 by the surface circumferential direction line segments x1, x2, x3, x4 and the surface radial direction line segments y1, y2, y3, y4, y5. Has been.

  The unit surface S includes surface circumferential direction line segments (for example, line segment x1 and line segment x2) adjacent in the tire radial direction, and surface radial direction line segments (for example, line segment y1 and line segment) adjacent in the tire circumferential direction. The surface defined by the four line segments with y2) is included. Further, on the unit surface S, adjacent surface radial direction line segments (for example, a line segment y1 and a line segment y2) in the tire circumferential direction, and a surface circumferential direction line segment on the tire radial direction outermost side (tire radial direction innermost side). A surface defined by three line segments with x1 (surface circumferential direction line segment x4) is also included.

  Further, as shown in FIG. 2A, the unit surface S is formed with a through hole 301a. The through holes 301a may be formed on all the unit surfaces S, or may be formed only on a specific unit surface S.

  It should be noted that the above-mentioned matters regarding the type 1 bead reinforcing layer 301 described with reference to FIGS. 3A and 3B also apply to the type 2 bead reinforcing layer 302 shown in FIG. 2B. In addition, an example of an intermediate type between the type 1 bead reinforcing layer 301 and the type 2 bead reinforcing layer 302, in which the surface circumferential direction line segment and the surface radial direction line segment are configured by both a straight line and a curved line. Are also included in the present embodiment, and similarly, the above items apply.

(Action etc.)
In recent years, many pneumatic tires have been developed in which bead reinforcing layers are annularly arranged in the tire circumferential direction along the extending direction of the bead filler. Up to now, such a bead reinforcing layer has been devised in its shape, disposition position, etc., and has mainly contributed to improvement of steering stability performance. However, depending on the shape of the bead reinforcement layer, an increase in rigidity that directly leads to an improvement in steering stability performance may be observed over a wide range in the tire radial direction. In such a case, the sidewall portion is rich in flexibility. Since sufficient flex zones could not be secured, it was sometimes impossible to achieve excellent load durability.

  In view of such circumstances, in the pneumatic tire according to the present embodiment, as shown in FIGS. 2 and 3, the bead reinforcing layer 301 has a plurality of bending points X1, X2, X3, X4, and Y1 appearing on two cross sections. , Y2, Y3, Y4, and Y5. Thereby, compared with the case where the bead reinforcement layer which consists only of the cord currently indicated by patent documents 1 is used, the rigidity of bead reinforcement layer 30 (301, 302) itself in the same size field of a tire radial direction, Can greatly increase. For this reason, even if the tire radial direction dimension of the bead reinforcement layer 30 is made smaller than before, it is possible to exhibit much higher steering stability performance than before. Moreover, as shown in FIG. 1, the flex zone can be ensured widely in the sidewall portion 20 by reducing the tire radial direction dimension of the bead reinforcing layer 30, and the load durability performance can be improved.

  Further, in the pneumatic tire of the present embodiment, as shown in FIG. 2 (a), a line having these bending points X1, X2, X3, X4, Y1, Y2, Y3, Y4, Y5 as the start point and the end point. A through hole 301a is formed in the unit surface S of the bead reinforcing layer 30 that is partitioned by the minute. Thereby, the rubber which comprises the bead filler 18 at the time of vulcanization flows into the tire width direction outer side through the through-hole 301a, and can improve the adhesiveness of the bead filler 18 and the rubber located in the tire width direction outer side. And by this adhesive improvement, it can suppress that the carcass ply 14 follows the bead reinforcement layer 30 at the time of load rolling of the pneumatic tire 1, and becomes wavy.

  As described above, in this embodiment, the bead reinforcement layer 30 (301, 302) shown in FIGS. 2 and 3 is arranged as shown in FIG. That is, in this embodiment, the bead reinforcement layer 30 has a three-dimensional structure, and the bead reinforcement layer 30 is provided with a through hole 30a. Thereby, the steering stability performance is improved by securing rigidity due to the presence of the bead reinforcing layer 30 itself, and the load durability performance is improved by sufficiently securing the flex zone in the sidewall portion.

  The pneumatic tire 1 according to the present embodiment has normal manufacturing processes, that is, a tire material mixing process, a tire material processing process, a green tire molding process, a vulcanization process, and an inspection process after vulcanization. It is obtained through

[Additional form]
Next, additional embodiments 1 to 4 that can be optionally implemented with respect to the basic embodiment of the pneumatic tire according to the present invention will be described.

(Additional form 1)
In the basic configuration, the bead reinforcement layer 30 is formed from the tire width direction inner side 10 [mm] to the tire width direction outer side 10 [mm] with reference to the tire width direction center line CCL1 of the carcass ply winding portion 14b shown in FIG. (Additional form 1) is preferable. In addition, although the arrangement | positioning area | region of the bead reinforcement layer 30 is as above-mentioned, this is restricted to the part which does not overlap with the winding part 14b of the carcass ply 14 by tire meridian sectional view. The bead reinforcement layer 30 is disposed within the bead filler 18 in the bead filler 18 by setting the tire width direction arrangement region of the bead reinforcement layer 30 from the tire width direction inner side 10 [mm] to the tire width direction outer side with reference to the tire width direction center line CCL1. Can be buried, and the steering stability performance can be greatly improved. Further, the region is located on the outer side in the tire width direction of the winding portion 14b of the carcass ply 14 by setting the region from the outer side 10 [mm] in the tire width direction to the inner side in the tire width direction with reference to the center line CCL1 in the tire width direction. The bead reinforcing layer 30 can be embedded in the side rubber, and load durability performance and steering stability performance can be improved.

(Additional form 2)
In the basic form and the like (the basic form and the form in which the additional form 1 is added to the basic form), as shown in FIG. 2A, the surface circumferential direction line segment x (x1, x2, x3, x4) and the surface diameter When at least part of the direction line segment y (y1, y2, y3, y4, y5) is a straight line, the bending angle and the second bending at the first bending points X1, X2, X3, and X4 The bending angles at the points Y1, Y2, Y3, Y4, Y5, the surface circumferential direction line segment x (x1, x2, x3, x4) and the surface radial direction line segment y (y1, y2, y3, y4, y5) It is preferable that each of the bending angles of the surface projection line projected onto the tire equatorial plane CL is 90 [°] or more and 170 [°] or less (additional form 2).

  Here, the bending angles at the first bending points X1, X2, X3, and X4 are the center lines in the tire width direction of the bead reinforcing layer 301 at the points X1, X2, X3, and X4 shown in FIG. It refers to the bending angle α (α1, α2, α3, α4) measured on CCL2. Further, the bending angles at the second bending points Y1, Y2, Y3, Y4, and Y5 are the tire widths of the bead reinforcing layer 301 at the points Y1, Y2, Y3, Y4, and Y5 shown in FIG. Bending angles β (β1, β2, β3, β4, β5) measured on the direction center line CCL3. In FIG. 3B, the bending angles β1 and β5 at the bending points Y1 and Y5 are not shown, but actually exist in the same manner as the bending angles β2, β3, and β4.

  Furthermore, the bending angle of the surface projection line segment obtained by projecting the surface circumferential direction line segment x1, x2, x3, x4 and the surface radial direction line segment y2, y3, y4 on the tire equatorial plane CL is as shown in FIG. Angle γ (γ11, γ12, γ13, γ14, γ21, γ22, γ23). That is, FIG. 4 shows tire circumferential equator planes x1, x2, x3, x4 and surface radial direction segments y2, y3, y4 appearing on the surface of the bead reinforcing layer 301 shown in FIG. It is a figure which shows the bending angle (gamma) ((gamma) 11, (gamma) 12, (gamma) 13, (gamma) 14, (gamma) 21, (gamma) 22, (gamma) 23) of the surface projection line segment x10, x20, x30, x40, y20, y30, y40 projected on CL.

  The bending angles γ21, γ22, and γ23 of the surface projected line segments y20, y30, and y40 of the surface radial direction line segments y2, y3, and y4 out of the bending angle α (α1 to α4) and the bending angle γ are 90 ° or more. By doing so, the generation of cracks starting from the bent portion can be suppressed, and the load durability performance can be improved. Further, by setting the bending angles α (α1 to α4) and the bending angles γ21, γ22, and γ23 to 170 ° or less, the riding comfort performance can be improved without excessively increasing the tire radial rigidity. it can.

  The bending angles γ11, γ12, γ13, and γ14 of the surface projected line segments x10, x20, x30, and x40 of the surface circumferential direction line segments x1, x2, x3, and x4 among the bending angles β (β2 to β4) and the bending angle γ are expressed as follows. By setting the angle to 90 [°] or more, it is possible to suppress the generation of cracks starting from the bent portion and improve the load durability performance. In addition, by setting the bending angle β (β2 to β4) and the bending angles γ11, γ12, γ13, and γ14 to 170 [°] or less, the rigidity in the tire width direction can be increased and the steering stability performance can be improved. .

  The angles α, β, and γ are all set to 135 ° or less to further improve the riding comfort performance based on the tire radial direction rigidity or the steering stability performance based on the tire width direction rigidity. it can.

(Additional form 3)
In a basic form or the like (a form obtained by adding at least one of the additional form 1 or 2 to the basic form and the basic form), as shown in FIG. 2B, the surface circumferential direction line segment x (x5, x6, x7). , X8) and at least a part of the surface radial direction line segment y (y6, y7, y8, y9, y10) are curves, the curves passing through the first bending points X5, X6, X7, X8 , The curvature radius of the curve passing through the second bending points Y6, Y7, Y8, Y9, Y10, the surface circumferential direction line segment x (x5, x6, x7, x8) and the surface radial direction line segment y (y6) , Y7, y8, y9, y10) are all projected to have a radius of curvature of a surface projection line segment of 0.5 [mm] to 25 [mm] (additional form 3) Is preferred. In addition, the surface circumferential direction line segment includes not only the line segments x5, x6, x7, and x8 shown in FIG. 2B, but also the outermost surface in the tire radial direction and the innermost surface in the tire radial direction of the bead reinforcement layer 302, respectively. It also includes line segments x9 and x10 that form a partition.

  Here, the radius of curvature of the curve passing through the first bending points X5, X6, X7, and X8 is the radius of curvature R1 (R15, R1) on the tire width direction center line CCL4 of the bead reinforcing layer 302 shown in FIG. R16, R17, R18). Further, the curvature radius of the curve passing through the second bending points Y6, Y7, Y8, Y9, and Y10 is the curvature radius R2 (R26) on the tire width direction center line CCL5 of the bead reinforcing layer 302 shown in FIG. , R27, R28, R29, R20).

  Further, the curvature radius of the surface projection line segment obtained by projecting the surface circumferential direction line segment x5, x6, x7, x8 and the surface radial direction line segment y6, y7, y8, y9, y10 onto the tire equatorial plane CL is shown in FIG. As shown in FIG. 6, the curvature radius R38 is representative of the curvature radius of the line segment extending in the tire radial direction, and the curvature radius R48 is representative of the curvature radius of the line segment extending in the tire width direction. ). That is, FIG. 6 shows tire circumferential equator planes x5, x6, x7, x8 and surface radial direction segments y7, y8, y9 appearing on the surface of the bead reinforcing layer 302 shown in FIG. It is a figure which shows the bending angle of the surface projection line segment x50, x60, x70, x80, y70, y80, y90 projected on CL.

  The curvature radius of the curve passing through the first bending points X5, X6, X7, and X8, the curvature radius of the curve passing through the second bending points Y6, Y7, Y8, Y9, and Y10, and the surface circumferential direction line segment x (x5, x6, x7, x8, x9, x10) and the surface radial line segment y (y6, y7, y8, y9, y10) are projected on the tire equatorial plane CL. By setting it to 5 [mm] or more, the generation of cracks starting from the bent portion can be suppressed, and the load durability performance can be enhanced.

  The curvature radius of the curve passing through the first bending points X5, X6, X7, and X8 and the curvature radii of the surface projection line segments y70, y80, and y90 obtained by projecting the surface radial direction line segments y7, y8, and y9 onto the tire equatorial plane CL. In both cases, the ride comfort performance can be improved without excessively increasing the tire radial rigidity by setting it to 25 mm or less. Further, the curvature radius of the curve passing through the second bending points Y6, Y7, y8, y9, Y10, and the surface projection line segment x50 obtained by projecting the surface circumferential direction segments x5, x6, x7, x8 onto the tire equator plane CL, By setting the curvature radii of x60, x70, and x80 to 25 [mm] or less, the rigidity in the tire width direction can be increased and the steering stability performance can be improved.

In addition, the curvature radius of the said curve can show | play the said effect on a still higher level each by setting it as 5 [mm] or more and 15 [mm] or less. Moreover, the curvature radius of the said curve can be suitably changed in each of a tire radial direction, a tire width direction, and a tire circumferential direction.

(Additional form 4)
In a basic form or the like (a form in which at least one of the additional forms 1 to 3 is added to the basic form and the basic form), the area of the through holes 301a and 302a occupying the surface area of the bead reinforcing layer 30 (301 and 302). The ratio is preferably 10 [%] to 60 [%] (additional form 4). Here, the surface area of the bead reinforcement layer 30 means the formation surface (either the front surface or the back surface) of the through holes 301a, 302a of the bead reinforcement layer 30 when the through holes 301a, 302a are not formed. The area of the thick portion of the bead reinforcing layer 30 is not included.

  By setting the ratio to 10% or more, the tire weight can be reduced and the rolling resistance performance can be improved. Further, by setting the above ratio to 10% or more, the rubber constituting the bead filler 18 at the time of vulcanization can more easily flow to the outside in the tire width direction through the through holes 301a and 302a, and the bead filler 18 and the tire width direction thereof. Adhesiveness with the rubber located outside can be further enhanced. Further, by further improving the adhesiveness, it is further suppressed that the carcass ply 14 follows the bead reinforcement layer 30 and becomes wavy when the pneumatic tire 1 rolls under load.

  Further, by setting the ratio to 60 [%] or less, the rigidity of the bead reinforcement layer 30 itself is kept high, and even if the tire radial direction dimension of the bead reinforcement layer 30 is smaller than before, it is far more than before. High steering stability performance can be demonstrated. Further, by further reducing the size of the bead reinforcing layer 30 in the tire radial direction, a wide flex zone can be secured in the sidewall portion 20, and the load durability performance can be further improved.

  In addition, the said effect can be show | played by a higher level each by making the said ratio into 20 [%] or more and 45 [%] or less. Moreover, it is preferable to change the said ratio suitably in each of a tire radial direction, a tire width direction, and a tire circumferential direction. For example, in the vicinity of the upper end of the bead filler 18 shown in FIG. 1 in the tire radial direction, the amount of the bead filler rubber is small, so that the adhesion of the bead reinforcing layer 30 may be lowered during vulcanization as compared with other tire radial portions. is there. Therefore, in the vicinity of the upper end of the bead filler 18 in the tire radial direction, it is preferable to increase the adhesiveness by setting the above-described ratio related to the bead reinforcing layer 30 to be relatively high.

(Additional form 5)
In a basic form or the like (a form in which at least one of the additional forms 1 to 4 is added to the basic form and the basic form), as shown in FIG. 7, the thickness T of the bead reinforcing layer 301 is 0.1 [mm]. It is preferable that it is 2.0 [mm] or less (additional form 5). By setting the thickness T to 0.1 [mm] or more, the steering stability performance can be further improved by ensuring sufficient rigidity by the bead reinforcing layer 301. Further, by setting the thickness T to 2.0 [mm] or less, the rolling resistance performance can be further improved without excessively increasing the tire weight.

  In addition, when the thickness T is 0.5 [mm] or more and 1.5 [mm] or less, each of the above-described effects can be achieved at a higher level.

  The bead reinforcement layer 301 (type 1) shown in FIG. 2A or the bead reinforcement layer 302 (type 2) shown in FIG. Conditions (where the bead reinforcing layers 301 and 302 are disposed on the outer side in the tire width direction with respect to the center line in the tire width direction of the upper portion of the carcass ply) (the outer position in the tire width direction of the bead reinforcing layer), 3 and 4 (angles α, β, and γ) shown in FIGS. 3 and 4 for type 1, and radii of curvature R1, R2, R3, and R4 shown in FIGS. 5 and 6 for type 2 (curvature radii R1 and R2). , R3, R4), the ratio of the area of the through-holes 301a, 302a to the surface area of the bead reinforcement layers 301, 302 (through-hole ratio), the thickness of the bead reinforcement layer (thickness T), and the tire radial direction of the bead reinforcement layer Dimension (dimension in the tire radial direction)) To prepare a pneumatic tire of Example 10 from Example 1. On the other hand, a pneumatic tire of a conventional example having the same structure as the pneumatic tire of Example 1 was produced except that the bead reinforcing layer disclosed in Patent Document 1 was provided.

  With respect to the conventional example and the pneumatic tires (test tires) of Examples 1 to 10, the tire size is 275 / 55R20 B7V, and the tire weight is measured for all these test tires (index of which the conventional example is 100). Evaluation), as well as steering stability performance, ride comfort performance, and load durability performance were evaluated. These results are also shown in Table 1. In Table 1, the thickness T of the conventional example is a total gauge of the cord and cord coat compound (reinforcing material) in a tire meridian cross-sectional view.

(Maneuvering stability)
Each test tire is assembled to a 20x8.5J rim as a front wheel at an air pressure of 230 kPa, and as a rear wheel is assembled to a 20x8.5J rim at an air pressure of 210 kPa, and these are mounted on a sedan type vehicle having a displacement of 2000 CC. The sensory evaluation by two panelists when traveling on a dry road surface at a speed of 120 km / h was carried out, and the average value was calculated. And based on this calculation result, the index evaluation which made the conventional example the standard (100) was performed. This evaluation shows that the larger the index, the higher the steering stability performance.

(Ride comfort performance)
Each test tire is assembled to a 20x8.5J rim as a front wheel at an air pressure of 230 kPa, and as a rear wheel is assembled to a 20x8.5J rim at an air pressure of 210 kPa, and these are mounted on a sedan type vehicle having a displacement of 2000 CC. For a comprehensive evaluation of the vertical push-up feeling and the horizontal vibration magnitude when traveling at a speed of 60 km / h on a dry road surface with a plurality of protrusions fixed to the ground, a sensory evaluation was conducted by two panelists. The average value was calculated. And based on this calculation result, the index evaluation which made the conventional example the standard (100) was performed. This evaluation shows that the higher the index, the higher the ride comfort performance.

(Load durability)
Each test tire was assembled on a rim of 20 × 9.5 J at an air pressure of 330 kPa, a load of 19.0 kN was applied, and the vehicle was run on a drum at a speed of 81 km. The running distance when a visually observable failure occurred was measured. And based on this measurement result, the index evaluation which made the conventional example the reference | standard (100) was performed. This evaluation shows that the greater the index, the longer the travel distance, that is, the higher the load durability performance.

  According to Table 1, the pneumatic tires of Examples 1 to 10 belong to the technical scope of the present invention (the bead reinforcing layer has a specific three-dimensional structure and a through hole is formed on the surface thereof). With respect to the above, it can be seen that at least the steering stability performance and the load durability performance are improved with respect to the conventional pneumatic tire which does not belong to the technical scope of the present invention.

  The present invention includes the following aspects.

(1) The bead core is disposed on the outer side in the tire radial direction, the bead filler disposed between the main body portion of the carcass ply and the winding portion, the tire filler extending along the extending direction of the bead filler, and the tire circumferential direction. In a pneumatic tire provided with a bead reinforcement layer extending in a ring shape,
The bead reinforcement layer has a first bending point at at least one position in the tire radial direction in the tire radial direction and the tire width direction sectional view, and the bead reinforcement in the tire circumferential direction and the tire width direction sectional view. The layer has a second bending point at at least two positions in the tire circumferential direction, and the surface of the bead reinforcing layer varies in at least one direction of the tire radial direction and the tire width direction from the first bending point. A surface circumferential line segment extending in the tire circumferential direction and a surface radial line segment extending in the tire radial direction while fluctuating in at least one direction of the tire circumferential direction and the tire width direction from the second bending point A pneumatic tire in which a plurality of unit surfaces defined by the above are formed, and through holes are formed in the unit surfaces.

  (2) The bead reinforcement layer is disposed in a region from the inner side 10 [mm] in the tire width direction to the outer side 10 [mm] in the tire width direction with reference to the center line in the tire width direction of the upper part of the carcass ply. The pneumatic tire according to (1) above.

  (3) A bending angle at the first bending point and a bending at the second bending point when at least a part of the surface circumferential direction line segment and the surface radial direction line segment is configured by a straight line. The angle and the bending angle of the surface projected line segment obtained by projecting the surface circumferential direction line segment and the surface radial direction line segment on the tire equatorial plane are both 90 [°] or more and 170 [°] or less, The pneumatic tire according to 1) or (2).

  (4) When at least a part of the surface circumferential direction line segment and the surface radial direction line segment is configured by a curve, the curvature radius of the curve passing through the first bending point and the second bending point are determined. The curvature radius of the curved line passing through and the curvature radius of the surface projection line segment obtained by projecting the surface circumferential direction line segment and the surface radial direction line segment onto the tire equator plane are both 0.5 [mm] or more and 25 [mm]. The pneumatic tire according to any one of (1) to (3), which is the following.

  (5) The ratio of the area of the through hole to the surface area of the bead reinforcing layer is 10 [%] or more and 60 [%] or less, according to any one of (1) to (4) above. Pneumatic tire.

  (6) The pneumatic tire according to any one of (1) to (5), wherein a thickness of the bead reinforcing layer is 0.1 [mm] or more and 1.0 [mm] or less.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 10 Bead part 12 Bead core 14 Carcass ply 14a Main part 14b Winding part 16 Reinforcement layer 18 Bead filler 20 Side wall part 30, 301, 302 Bead reinforcement layer 301a, 302a Through-hole CCL1 Tire width of winding part 14b of carcass ply Direction center line CCL2, CCL3 Tire width direction center line of bead reinforcement layer 301 CCL4, CCL5 Tire width direction center line of bead reinforcement layer 302 CL Tire equatorial plane R1 (R15, R16, R17, R18), R2 (R26, R27, R28, R29, R20), R3 (R38), R4 (R48) Radius of curvature T Thickness of bead reinforcing layer 301 X (X1, X2, X3, X4, X5, X6, X7, X8) First bending point x ( x1, x2, x3, x4, x5, x6, x7, x8, x9 x10) Surface circumferential direction line segment x50, x60, x70, x80 Surface projection line segment Y (Y1, Y2, Y3, Y4, Y5, Y6, Y7, Y8, Y9, Y10) Second bending point y (y1, y2) , Y3, y4, y5, y6, y7, y8, y9, y10) Surface radial direction line segment y70, y80, y90 Surface projection line segment α (α1, α2, α3, α4), β (β2, β3, β4) , Γ (γ11, γ12, γ13, γ14, γ21, γ22, γ23) Bending angle

Claims (6)

Outside the bead core in the tire radial direction, the bead filler disposed between the main body of the carcass ply and the upper part of the carcass ply, and disposed along the extending direction of the bead filler, and annular in the tire circumferential direction In a pneumatic tire provided with an extended bead reinforcement layer,
In the tire radial direction and the tire width direction sectional view, the bead reinforcing layer has a first bending point at at least one position in the tire radial direction position,
In the tire circumferential direction and the tire width direction cross-sectional view, the bead reinforcing layer has a second bending point at at least two positions in the tire circumferential direction;
On the surface of the bead reinforcing layer, a surface circumferential direction line segment extending in the tire circumferential direction while changing in at least one direction of the tire radial direction and the tire width direction from the first bending point, and the second bending point A plurality of unit surfaces formed by partitioning with a surface radial direction line segment extending in the tire radial direction while varying in at least one direction of the tire circumferential direction and the tire width direction,
A pneumatic tire in which a through hole is formed in the unit surface.   The bead reinforcing layer is disposed in a region from the tire width direction inner side 10 [mm] to the tire width direction outer side 10 [mm] with reference to the tire width direction center line of the upper portion of the carcass ply. The pneumatic tire according to claim 1.   A bending angle at the first bending point, a bending angle at the second bending point, and at least a part of the surface circumferential direction line segment and the surface radial direction line segment are configured by straight lines; and The bending angle of a surface projection line segment obtained by projecting the surface circumferential direction line segment and the surface radial direction line segment onto a tire equator plane is 90 ° or more and 170 ° or less. Pneumatic tire described in 2.   When at least a part of the surface circumferential direction line segment and the surface radial direction line segment is configured by a curve, a curvature radius of a curve passing through the first bending point, a curve passing through the second bending point, The curvature radius, and the curvature radius of the surface projection line segment obtained by projecting the surface circumferential direction line segment and the surface radial direction line segment on the tire equator plane are both 0.5 mm or more and 25 mm or less. The pneumatic tire according to any one of claims 1 to 3.   The pneumatic tire according to any one of claims 1 to 4, wherein a ratio of an area of the through hole to a surface area of the bead reinforcing layer is 10% or more and 60% or less.   The pneumatic tire according to any one of claims 1 to 5, wherein a thickness of the bead reinforcing layer is 0.1 [mm] or more and 1.0 [mm] or less.

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